심리학의 원리/심리학의 원리2

위키문헌 ― 우리 모두의 도서관.


THE PRINCIPLES OF PSYCHOLOGY [1][2]


BY

WILLIAM JAMES

PROFESSOR OF PSYCHOLOGY IN HARVARD UNIVERSITY

IN TWO VOLUMES

VOL II.

NEW YORK

HENRY HOLT AND COMPANY

1918



CONTENTS.


CHAPTER XVII.

SENSATION

Its distinction from perception. Its cognitive function--acquaintance with qualities. No pure sensations after the first days of life. The 'relativity of knowledge'. The law of contrast. The psychological and the physiological theories of it. Hering's experiments. The 'eccentric projection' of sensations.


CHAPTER XVIII.

IMAGINATION

Our images are usually vague. Vague images not necessarily general notions. Individuals differ in imagination; Gabon's researches. The 'visile' type, 58. The 'audile' type. The 'motile' type. Tactile images, 65. The neural process of imagination. Its relations to that of sensation.


CHAPTER XIX.

THE PERCEPTION OF 'THINGS'

Perception and sensation. Perception is of definite and probable things. Illusions;--of the first type;--of the second type. The neural process in perception. 'Apperception'. Is perception an unconscious inference? Hallucinations, 114. The neural process in hallucination. Binet's theory. 'Perception-time'.


CHAPTER XX.

THE PERCEPTION OF SPACE

The feeling of crude extensity. The perception of spatial order. Space-'relations'. The meaning of localization. 'Local signs'. The construction of 'real' space. The subdivision of the original sense-spaces. The sensation of motion over surfaces. The measurement of the sense-spaces by each other. Their summation. Feelings of movement in joints. Feelings of muscular contraction. Summary so far. How the blind perceive space. Visual space. Helmholtz and Reid on the test of a sensation. The theory of identical points. The theory of projection. Ambiguity of retinal impressions;--of eye-movements. The choice of the visual reality. Sensations which we ignore. Sensations which seem suppressed. Discussion of Wundt's and Helmholtz's reasons for denying that retinal sensations are of extension. Summary. Historical remarks.


CHAPTER XXI.

THE PERCEPTION OF REALITY

Belief and its opposites. The various orders of reality. 'Practical' realities. The sense of our own bodily existence is the nucleus of all reality. The paramount reality of sensations. The influence of emotion and active impulse on belief. Belief in theories. Doubt. Relations of belief and will.


CHAPTER XXII.

REASONING

'Recepts'. In reasoning, we pick out essential qualities. What is meant by a mode of conceiving. What is involved in the existence of general propositions. The two factors of reasoning. Sagacity. The part played by association by similarity. The intellectual contrast between brute and man: association by similarity the fundamental human distinction. Different orders of human genius.


CHAPTER XXIII.

THE PRODUCTION OF MOVEMENT

The diffusive wave. Every sensation produces reflex effects on the whole organism.


CHAPTER XXIV.

INSTINCT

Its definition. Instincts not always blind or invariable. Two principles of non-uniformity in instincts: 1) Their inhibition by habits; 2) Their transitoriness. Man has more instincts than any other mammal. Reflex impulses. Imitation. Emulation. Pugnacity. Sympathy. The hunting instinct. Fear. Acquisitiveness. Constructiveness. Play. Curiosity. Sociability and shyness. Secretiveness. Cleanliness. Shame. Love. Maternal love.


CHAPTER XXV.

THE EMOTIONS

Instinctive reaction and emotional expression shade imperceptibly into each other. The expression of grief; of fear; of hatred. Emotion is a consequence, not the cause, of the bodily expression. Difficulty of testing this view. Objections to it discussed. The subtler emotions, 468. No special brain-centres for emotion. Emotional differences between individuals. The genesis of the various emotions.


CHAPTER XXVI.

WILL

Voluntary movements: they presuppose a memory of involuntary movements. Kinæsthetic impressions, 488. No need to assume feelings of innervation. The 'mental cue' for a movement may be an image of its visual or auditory effects as well as an image of the way it feels. Ideo-motor action. Action after deliberation. Five types of decision. The feeling of effort. Unhealthiness of will: 1) The explosive type; 2) The obstructed type. Pleasure and pain are not the only springs of action. All consciousness is impulsive. What we will depends on what idea dominates in our mind. The idea's outward effects follow from the cerebral machinery. Effort of attention to a naturally repugnant idea is the essential feature of willing. The free-will controversy. Psychology, as a science, can safely postulate determinism, even if free-will be true. The education of the Will. Hypothetical brain-schemes.


CHAPTER XXVII.

HYPNOTISM

Modes of operating and susceptibility. Theories about the hypnotic state. The symptoms of the trance.


CHAPTER XXVIII.

NECESSARY TRUTHS AND THE EFFECTS OF EXPERIENCE

Programme of the chapter. Elementary feelings are innate. The question refers to their combinations. What is meant by 'experience'. Spencer on ancestral experience. Two ways in which new cerebral structure arises: the 'back-door' and the 'front-door' way. The genesis of the elementary mental categories. The genesis of the natural sciences. Scientific conceptions arise as accidental variations. The genesis of the pure sciences. Series of evenly increasing terms. The principle of mediate comparison. That of skipped intermediaries. Classification. Predication. Formal logic. Mathematical propositions. Arithmetic. Geometry. Our doctrine is the same as Locke's. Relations of ideas _v._ couplings of things The natural sciences are inward ideal schemes with which the order of nature proves congruent. Metaphysical principles are properly only postulates. Æsthetic and moral principles are quite incongruent with the order of nature. Summary of what precedes. The origin of instincts. Insufficiency of proof for the transmission to the next generation of acquired habits. Weismann's views. Conclusion.

INDEX.



PSYCHOLOGY.

CHAPTER XVII.

SENSATION.


After inner perception, outer perception! The next three chapters will treat of the processes by which we cognize at all times the present world of space and the material things which it contains. And first, of the process called Sensation.


SENSATION AND PERCEPTION DISTINGUISHED.


_The words Sensation and Perception_ do not carry very definitely discriminated meanings in popular speech, and in Psychology also their meanings run into each other. Both of them name processes in which we cognize an objective world; both (under normal conditions) need the stimulation of incoming nerves ere they can occur; Perception always involves Sensation as a portion of itself; and Sensation in turn never takes place in adult life without Perception also being there. They are therefore names for different cognitive _functions_, not for different sorts of mental _fact_. The nearer the object cognized comes to being a simple quality like 'hot,' 'cold,' 'red,' 'noise,' 'pain,' apprehended irrelatively to other things, the more the state of mind approaches pure sensation. The fuller of relations the object is, on the contrary; the more it is something classed, located, measured, compared, assigned to a function, etc., etc.; the more unreservedly do we call the state of mind a perception, and the relatively smaller is the part in it which sensation plays.

_Sensation, then, so long as we take the analytic point of view, differs from Perception only in the extreme simplicity of its object or content._[1] Its function is that of mere _acquaintance_ with a fact. Perception's function, on the other hand, is knowledge _about_[2] a fact; and this knowledge admits of numberless degrees of complication. But in both sensation and perception we perceive the fact as an _immediately present outward reality_, and this makes them differ from 'thought' and 'conception,' whose objects do not appear present in this immediate physical way. _From the physiological_ _point of view both sensations and perceptions differ from 'thoughts'_ (in the narrower sense of the word) _in the fact that nerve-currents coming in from the periphery are involved in their production. In perception these nerve-currents arouse voluminous associative or reproductive processes in the cortex; but when sensation occurs alone, or with a minimum of perception, the accompanying reproductive processes are at a minimum too._

I shall in this chapter discuss some general questions more especially relative to Sensation. In a later chapter perception will take its turn. I shall entirely pass by the classification and natural history of our special 'sensations,' such matters finding their proper place, and being sufficiently well treated, in all the physiological books.[3]


THE COGNITIVE FUNCTION OF SENSATION.


_A pure sensation is an abstraction;_ and when we adults talk of our 'sensations' we mean one of two things: either certain _objects_, namely simple _qualities_ or _attributes_ like _hard, hot, pain;_ or else those of our thoughts in which acquaintance with these objects is least combined with knowledge about the relations of them to other things. As we can only think or talk about the relations of objects with which we have _acquaintance_ already, we are forced to postulate a function in our thought whereby we first become aware of the _bare immediate natures_ by which our several objects are distinguished. This function is sensation. And just as logicians always point out the distinction between substantive terms of discourse and relations found to obtain between them, so psychologists, as a rule, are ready to admit this function, of the vision of the terms or matters meant, as something distinct from the knowledge about them and of their relations _inter se_. Thought with the former function is sensational, with the latter, intellectual. Our earliest thoughts are almost exclusively sensational. They merely give us a set of _thats_, or _its_, of subjects of discourse, with their relations not brought out. The first time we see _light_, in Condillac's phrase we _are_ it rather rather than see it. But all our later optical knowledge is about what this experience gives. And though we were struck blind from that first moment, our scholarship in the subject would lack no essential feature so long as our memory remained. In training-institutions for the blind they teach the pupils as much _about_ light as in ordinary schools. Reflection, refraction, the spectrum, the ether-theory, etc., are all studied. But the best taught born-blind pupil of such an establishment yet lacks a knowledge which the least instructed seeing baby has. They can never show him what light is in its 'first intention'; and the loss of that sensible knowledge no book-learning can replace. All this is so obvious that we usually find sensation 'postulated' as an element of experience, even by those philosophers who are least inclined to make much of its importance, or to pay respect to the knowledge which it brings.[4]

But the trouble is that most, if not all, of those who admit it, admit it as a fractional _part_ of the thought, in the old-fashioned atomistic sense which we have so often criticised.

Take the pain called toothache for example. Again and again we feel it and greet it as the same real item in the universe. We must therefore, it is supposed, have a distinct pocket for it in our mind into which it and nothing else will fit. This pocket, when filled, is the sensation of toothache; and must be either filled or half-filled whenever and under whatever form toothache is present to our thought, and whether much or little of the rest of the mind be filled at the same time. Thereupon of course comes up the paradox and mystery: If the knowledge of toothache be pent up in this separate mental pocket, how can it be known _cum alio_ or brought into one view with anything else? This pocket knows nothing else; no other part of the mind knows toothache. The knowing of toothache _cum alio_ must be a miracle. And the miracle must have an Agent. And the Agent must be a Subject or Ego 'out of time,'--and all the rest of it, as we saw in Chapter X. And then begins the well-worn round of recrimination between the sensationalists and the spiritualists, from which we are saved by our determination from the outset to accept the psychological point of view, and to admit knowledge whether of simple toothaches or of philosophic systems as an ultimate fact. There are realities and there are 'states of mind,' and the latter know the former; and it is just as wonderful for a state of mind to be a 'sensation' and know a simple pain as for it to be a thought and know a system of related things.[5] But there is no reason to suppose that when different states of mind know different things about the same toothache, they do so by virtue of their all _containing_ faintly or vividly the original pain. Quite the reverse. The by-gone sensation of my gout was painful, as Reid somewhere says; the _thought_ of the same gout as by-gone is pleasant, and in no respect resembles the earlier mental state.

Sensations, then, first make us acquainted with innumerable things, and then are replaced by thoughts which know the same things in altogether other ways. And Locke's main doctrine remains eternally true, however hazy some of his language may have been, that

"though there be a great number of considerations wherein things
may be compared one with another, and so a multitude of relations;
yet they all _terminate in_, and are concerned about, those simple
ideas[6] either of sensation or reflection, which I think to be the
whole materials of all our knowledge.... The simple ideas we receive
from sensation and reflection are the _boundaries_ of our thoughts;
beyond which, the mind whatever efforts it would make, is not able to
advance one jot; nor can it make any discoveries when it would pry
into the nature and hidden causes of those ideas."[7]

The nature and hidden causes of ideas will never be unravelled till the _nexus_ between the brain and consciousness is cleared up. All we can say now is that sensations are _first_ things in the way of consciousness. Before conceptions can come, sensations must have come; but before sensations come, no psychic fact need have existed, a nerve-current is enough. If the nerve-current be not given, nothing else will take its place. To quote the good Locke again:

"It is not in the power of the most exalted wit or enlarged
understanding, by any quickness or variety of thoughts, to invent or
frame one new simple idea [i.e. sensation] in the mind.... I would
have any one try to fancy any taste which had never affected his
palate, or frame the idea of a scent he had never smelt; and when
he can do this, I will also conclude that a blind man hath ideas of
colors, and a deaf man true distinct notions of sounds."[8]

The brain is so made that all currents in it run one way. Consciousness of some sort goes with all the currents, but it is only when new currents are entering that it has the sensational _tang_. And it is only then that consciousness directly _encounters_ (to use a word of Mr. Bradley's) a reality outside itself.

The difference between such encounter and all conceptual knowledge is very great. A blind man may know all _about_ the sky's blueness, and I may know all _about_ your toothache, conceptually; tracing their causes from primeval chaos, and their consequences to the crack of doom. But so long as he has not felt the blueness, nor I the toothache, our knowledge, wide as it is, of these realities, will be hollow and inadequate. Somebody must _feel_ blueness, somebody must _have_ toothache, to make human knowledge of these matters real. Conceptual systems which neither began nor left off in sensations would be like bridges without piers. Systems about fact must plunge themselves into sensation as bridges plunge their piers into the rock. Sensations are the stable rock, the _terminus a quo_ and the _terminus ad quem_ of thought. To find such termini is our aim with all our theories--to conceive first when and where a certain sensation may be had, and then to have it. Finding it stops discussion. Failure to find it kills the false conceit of knowledge. Only when you deduce a possible sensation for me from your theory, and give it to me when and where the theory requires, do I begin to be sure that your thought has anything to do with truth.

_Pure sensations can only be realized in the earliest days of life._ They are all but impossible to adults with memories and stores of associations acquired. Prior to all impressions on sense-organs the brain is plunged in deep sleep and consciousness is practically non-existent. Even the first weeks after birth are passed in almost unbroken sleep by human infants. It takes a strong message from the sense-organs to break this slumber. In a new-born brain this gives rise to an absolutely pure sensation. But the experience leaves its 'unimaginable touch' on the matter of the convolutions, and the next impression which a sense-organ transmits produces a cerebral reaction in which the awakened vestige of the last impression plays its part. Another sort of feeling and a higher grade of cognition are the consequence; and the complication goes on increasing till the end of life, no two successive impressions falling on an identical brain, and no two successive thoughts being exactly the same. (See Vol. I, p. 230 ff.)

_The first sensation which an infant gets is for him the Universe._ And the Universe which he later comes to know is nothing but an amplification and an implication of that first simple germ which, by accretion on the one hand and intussusception on the other, has grown so big and complex and articulate that its first estate is unrememberable. In his dumb awakening to the consciousness of _something there_, a mere _this_ as yet (or something for which even the term _this_ would perhaps be too discriminative, and the intellectual acknowledgment of which would be better expressed by the bare interjection 'lo!'), the infant encounters an object in which (though it be given in a pure sensation) all the 'categories of the understanding' are contained. _It has objectivity, unity, substantiality, causality, in the full sense in which any later object or system of objects has these things._ Here the young knower meets and greets his world; and the miracle of knowledge bursts forth, as Voltaire says, as much in the infant's lowest sensation as in the highest achievement of a Newton's brain. The physiological condition of this first sensible experience is probably nerve-currents coming in from many peripheral organs at once. Later, the one confused Fact which these currents cause to appear is perceived to be many facts, and to contain many qualities.[9] For as the currents vary, and the brain-paths are moulded by them, other thoughts with other 'objects' come, and the 'same thing' which was apprehended as a present _this_ soon figures as a past _that_, about which many unsuspected things have come to light. The principles of this development have been laid down already in Chapters XII and XIII, and nothing more need here be added to that account.


"THE RELATIVITY OF KNOWLEDGE."


To the reader who is tired of so much _Erkenntnisstheorie_ I can only say that I am so myself, but that it is indispensable, in the actual state of opinions about Sensation, to try to clear up just what the word means. Locke's pupils seek to do the impossible with sensations, and against them we must once again insist that sensations 'clustered together' cannot build up our more intellectual states of mind. Plato's earlier pupils used to admit Sensation's existence, grudgingly, but they trampled it in the dust as something corporeal, non-cognitive, and vile.[10] His latest followers seem to seek to crowd it out of existence altogether. The only reals for the neo-Hegelian writers appear to be _relations_, relations without terms, or whose terms are only speciously such and really consist in knots, or gnarls of relations finer still _in infinitum_.

"Exclude from what we have considered real all qualities constituted
by relation, we find that none are left." "Abstract the many relations
from the one thing and there is nothing.... Without the relations it
would not exist at all."[11] "The single feeling is nothing real."
"On the recognition of relations as constituting the _nature_ of
ideas, rests the possibility of any tenable theory of their reality."

Such quotations as these from the late T. H. Green[12] would be matters of curiosity rather than of importance, were it not that sensationalist writers themselves believe in a so-called 'Relativity of Knowledge,' which, if they only understood it, they would see to be identical with Professor Green's doctrine. They tell us that the relation of sensations to each other is something belonging to their essence, and that no one of them has an absolute content:

"That, e.g., black can only be felt in contrast to white, or at
least in distinction from a paler or a deeper black; similarly a
tone or a sound only in alternation with others or with silence; and
in like manner a smell, a taste, a touch, only, so to speak, _in
statu nascendi_, whilst, when the stimulus continues, all sensation
disappears. This all seems at first sight to be splendidly consistent
both with itself and with the facts. But looked at more closely, it is
seen that neither is the case."[13]

The two leading facts from which the doctrine of universal relativity derives its wide-spread credit are these:

1) The _psychological fact_ that so much of our actual knowledge _is_ of the relations of things--even our simplest sensations in adult life are habitually referred to classes as we take them in; and

2) The _physiological fact_ that our senses and brain must have periods of change and repose, else we cease to feel and think.

Neither of these facts proves anything about the presence or non-presence to our mind of absolute qualities with which we become sensibly acquainted. Surely not the psychological fact; for our inveterate love of relating and comparing things does not alter the intrinsic qualities or nature of the things compared, or undo their absolute givenness. And surely not the physiological fact; for the length of time during which we can feel or attend to a quality is altogether irrelevant to the intrinsic constitution of the quality felt. The time, moreover, is long enough in many instances, as sufferers from neuralgia know.[14] And the doctrine of relativity, not proved by these facts, is flatly disproved by other facts even more patent. So far are we from not knowing (in the words of Professor Bain) "any one thing by itself, but only the difference between it and another thing," that if this were true the whole edifice of our knowledge would collapse. If all we felt were the _difference_ between the _C_ and _D_, or _c_ and _d_, on the musical scale, that being the same in the two pairs of notes, the pairs themselves would be the same, and language could get along without substantives. But Professor Bain does not mean seriously what he says, and we need spend no more time on this vague and popular form of the doctrine.[15] The facts which seem to hover before the minds of its champions are those which are best described under the head of a physiological law.


THE LAW OF CONTRAST.


I will first enumerate the main facts which fall under this law, and then remark upon what seems to me their significance for psychology.[16]

[Nowhere are the phenomena of contrast better exhibited, and their laws more open to accurate study, than in connection with the sense of sight. Here both kinds--simultaneous and successive--can easily be observed, for they are of constant occurrence. Ordinarily they remain unnoticed, in accordance with the general law of economy which causes us to select for conscious notice only such elements of our object as will serve us for æsthetic or practical utility, and to neglect the rest; just as we ignore the double images, the _mouches volantes_, etc., which exist for everyone, but which are not discriminated without careful attention. But by attention we may easily discover the general facts involved in contrast. We find that _in general the color and brightness of one object always apparently affect the color and brightness of any other object seen simultaneously with it or immediately after_.

In the first place, if we look for a moment at any surface and then turn our eyes elsewhere, the complementary color and opposite degree of brightness to that of the first surface tend to mingle themselves with the color and the brightness of the second. This is _successive contrast_. It finds its explanation in the fatigue of the organ of sight, causing it to respond to any particular stimulus less and less readily the longer such stimulus continues to act. This is shown clearly in the very marked changes which occur in case of continued fixation of one particular point of any field. The field darkens slowly, becomes more and more indistinct, and finally, if one is practised enough in holding the eye perfectly steady, slight differences in shade and color may entirely disappear. If we now turn aside the eyes, a negative after-image of the field just fixated at once forms, and mingles its sensations with those which may happen to come from anything else looked at. This influence is distinctly evident only when the first surface has been 'fixated' without movement of the eyes. It is, however, none the less present at all times, even when the eye wanders from point to point, causing each sensation to be modified more or less by that just previously experienced. On this account successive contrast is almost sure to be present in cases of simultaneous contrast, and to complicate the phenomena.

A _visual image is modified not only by other sensations just previously experienced, but also by all those experienced simultaneously with it, and especially by such as proceed from contiguous portions of the retina_. This is the phenomenon of _simultaneous contrast_. In this, as in successive contrast, both brightness and hue are involved. A bright object appears still brighter when its surroundings are darker than itself, and darker when they are brighter than itself. Two colors side by side are apparently changed by the admixture, with each, of the complement of the other. And lastly, a gray surface near a colored one is tinged with the complement of the latter.[17]

The phenomena of simultaneous contrast in sight are so complicated by other attendant phenomena that it is difficult to isolate them and observe them in their purity. Yet it is evidently of the greatest importance to do so, if one would conduct his investigations accurately. Neglect of this principle has led to many mistakes being made in accounting for the facts observed. As we have seen, if the eye is allowed to wander here and there about the field as it ordinarily does, successive contrast results and allowance must be made for its presence. It can be avoided only by carefully fixating with the well-rested eye a point of one field, and by then observing the changes which occur in this field when the contrasting field is placed by its side. Such a course will insure pure simultaneous contrast. But even thus it lasts in its purity for a moment only. It reaches its maximum of effect immediately after the introduction of the contrasting field, and then, if the fixation is continued, it begins to weaken rapidly and soon disappears; thus undergoing changes similar to those observed when any field whatever is fixated steadily and the retina becomes fatigued by unchanging stimuli. If one continues still further to fixate the same point, the color and brightness of one field tend to spread themselves over and mingle with the color and brightness of the neighboring fields, thus substituting '_simultaneous induction_' for simultaneous contrast.

Not only must we recognize and eliminate the effects of successive contrast, of temporal changes due to fixation, and of simultaneous induction, in analyzing the phenomena of simultaneous contrast, but we must also take into account _various other influences which modify its effects_. Under favorable circumstances the contrast-effects are very striking, and did they always occur as strongly they could not fail to attract the attention. But they are not always clearly apparent, owing to various disturbing causes which form no exception to the laws of contrast, but which have a modifying effect on its phenomena. When, for instance, the ground observed has many distinguishable features--a _coarse grain, rough surface, intricate pattern,_ etc.--the contrast effect appears weaker. This does not imply that the effects of contrast are absent, but merely that the resulting sensations are overpowered by the many other stronger sensations which entirely occupy the attention. On such a ground a faint negative after-image--undoubtedly due to retinal modifications--may become invisible; and even weak objective differences in color may become imperceptible. For example, a faint spot or grease-stain on woollen cloth, easily seen at a distance, when the fibres are not distinguishable, disappears when closer examination reveals the intricate nature of the surface.

Another frequent cause of the apparent absence of contrast is the presence of narrow dark intermediate fields, such as are formed by _bordering a field with black lines, or by the shaded contours of objects_. When such fields interfere with the contrast, it is because black and white can absorb much color without themselves becoming clearly colored; and because such lines separate other fields too far for them to distinctly influence one another. Even weak objective differences in color may be made imperceptible by such means.

A third case where contrast does not clearly appear is where the _color of the contrasting fields is too weak or too intense_, or where there is _much difference in brightness between the two fields_. In the latter case, as can easily be shown, it is the contrast of brightness which interferes with the color-contrast and makes it imperceptible. For this reason contrast shows best between fields of about equal brightness. But the intensity of the color must not be too great, for then its very darkness necessitates a dark contrasting field which is too absorbent of induced color to allow the contrast to appear strongly. The case is similar if the fields are too light.

_To obtain the best contrast-effects, therefore, the contracting fields should be near together, should not be separated by shadows or black lines, should be of homogeneous texture, and should be of about equal brightness and medium intensity of color._ Such conditions do not often occur naturally, the disturbing influences being present in case of almost all ordinary objects, thus making the effects of contrast far less evident. To eliminate these disturbances and to produce the conditions most favorable for the appearance of good contrast-effects, various experiments have been devised, which will be explained in comparing the rival theories of explanation.

      *       *       *       *       *

There are _two theories--the psychological and the physiological_--which attempt to explain the phenomena of contrast.

Of these the _psychological one_ was the first to gain prominence. _Its most able advocate has been Helmholtz. It explains contrast as a_ DECEPTION OF JUDGMENT. In ordinary life our sensations have interest for us only so far as they give us practical knowledge. Our chief concern is to recognize objects, and we have no occasion to estimate exactly their absolute brightness and color. Hence we gain no facility in so doing, but neglect the constant changes in their shade, and are very uncertain as to the exact degree of their brightness or tone of their color. When objects are near one another "we are inclined to consider those differences which are clearly and surely perceived as greater than those which appear uncertain in perception or which must be judged by aid of memory,"[18] just as we see a medium-sized man taller than he really is when he stands beside a short man. Such deceptions are more easily possible in the judgment of small differences than of large ones; also where there is but one element of difference instead of many. In a large number of cases of contrast, in all of which a whitish spot is surrounded on all sides by a colored surface--Meyer's experiment, the mirror experiment, colored shadows, etc., soon to be described--the contrast is produced, according to Helmholtz, by the fact that "a colored illumination or a transparent colored covering appears to be spread out over the field, and observation does not show directly that it fails on the white spot."[19] We therefore believe that we see the latter through the former color. Now

"Colors have their greatest importance for us in so far as they are
properties of bodies and can serve as signs for the recognition
of bodies.... We have become accustomed, in forming a judgment in
regard to the colors of bodies, to eliminate the varying brightness
and color of the illumination. We have sufficient opportunity to
investigate the same colors of objects in full sunshine, in the blue
light of the clear sky, in the weak white light of a cloudy day, in
the reddish-yellow light of the sinking sun or of the candle. Moreover
the colored reflections of surrounding objects are involved. Since
we see the same colored objects under these varying illuminations,
we learn to form a correct conception of the color of the object in
spite of the difference in illumination, i.e. to judge how such an
object would appear in white illumination; and since only the constant
color of the object interests us, we do not become conscious of the
particular sensations on which our judgment rests. So also we are
at no loss, when we see an object through a colored covering, to
distinguish what belongs to the color of the covering and what to
the object. In the experiments mentioned we do the same also where
the covering over the object is not at all colored, because of the
deception into which we fall, and in consequence of which we ascribe
to the body a false color, the color complementary to the colored
portion of the covering."[20]

We think that we see the complementary color through the colored covering,--for these two colors together would give the sensation of white which is actually experienced. If, however, in any way the white spot is recognized as an independent object, or if it is compared with another object known to be white, our judgment is no longer deceived and the contrast does not appear.

"As soon as the contrasting field is recognized as an independent
body which lies above the colored ground, or even through an adequate
tracing of its outlines is seen to be a separate field, the contrast
disappears. Since, then, the judgment of the spatial position, the
material independence, of the object in question is decisive for the
determination of its color, it follows that the contrast-color arises
not through an act of sensation but through an act of judgment."[21]

In short, the apparent change in color or brightness through contrast is due to no change in excitation of the organ, to no change in sensation; but in consequence of a false judgment the unchanged sensation is wrongly interpreted, and thus leads to a changed _perception_ of the brightness or color.

      *       *       *       *       *

In opposition to this theory has been developed one which attempts to explain all cases of contrast as depending purely on _physiological action of the terminal apparatus of vision. Hering is the most prominent supporter of this view._ By great originality in devising experiments and by insisting on rigid care in conducting them, he has been able to detect the faults in the psychological theory and to practically establish the validity of his own. Every visual sensation, he maintains, is correlated to a physical process in the nervous apparatus. Contrast is occasioned, not by a false idea resulting from unconscious conclusions, but by the fact that the excitation of any portion of the retina--and the consequent sensation--depends not only on its own illumination, but on that of the rest of the retina as well.

"If this psycho-physical process is aroused, as usually happens, by
light-rays impinging on the retina, its nature depends not only on
the nature of these rays, but also on the constitution of the entire
nervous apparatus which is connected with the organ of vision, and on
the state in which it finds itself."[22]

When a limited portion of the retina is aroused by external stimuli, the rest of the retina, and especially the immediately contiguous parts, tends to react also, and in such a way as to produce therefrom the sensation of the opposite degree of brightness and the complementary color to that of the directly-excited portion. When a gray spot is seen alone, and again when it appears colored through contrast, the objective light from the spot is in both cases the same. Helmholtz maintains that the neural process and the corresponding _sensation_ also remain unchanged, but are differently _interpreted_; Hering, that the neural process and the sensation are themselves changed, and that the 'interpretation' is the direct conscious correlate of the altered retinal conditions. According to the one, the contrast is psychological in its origin; according to the other, it is purely physiological. In the cases cited above where the contrast-color is no longer apparent--on a ground with many distinguishable features, on a field whose borders are traced with black lines, etc.,--the psychological theory, as we have seen, attributes this to the fact that under these circumstances we judge the smaller patch of color to be an independent object on the surface, and are no longer deceived in judging it to be something over which the color of the ground is drawn. The physiological theory, on the other hand, maintains that the contrast-effect is still produced, but that the conditions are such that the slight changes in color and brightness which it occasions become imperceptible.

      *       *       *       *       *

The two theories, stated thus broadly, may seem equally plausible. Hering, however, has conclusively proved, by experiments with after-images, that the process on one part of the retina does modify that on neighboring portions, under conditions where deception of judgment is impossible.[23] A careful examination of the facts of contrast will show that its phenomena must be due to this cause. _In all the cases which one may investigate it will be seen that the upholders of the psychological theory have failed to conduct their experiments with sufficient care._ They have not excluded successive contrast, have overlooked the changes due to steady fixation, and have failed to properly account for the various modifying influences which have been mentioned above. We can easily establish this if we examine the most striking experiments in simultaneous contrast.

Of these one of the best known and most easily arranged is that known as _Meyer's experiment_. A scrap of gray paper is placed on a colored background, and both are covered by a sheet of transparent white paper. The gray spot then assumes a contrast-color, complementary to that of the background, which shines with a whitish tinge through the paper which covers it. Helmholtz explains the phenomenon thus:

"If the background is green, the covering-paper itself appears to be
of a greenish color. If now the substance of the paper extends without
apparent interruption over the gray which lies under it, we think that
we see an object glimmering through the greenish paper, and such an
object must in turn be rose-red, in order to give white light. If,
however, the gray spot has its limits so fixed that it appears to be
an independent object, the continuity with the greenish portion of the
surface fails, and we regard it as a gray object which lies on this
surface."[24]

The contrast-color may thus be made to disappear by tracing in black the outlines of the gray scrap, or by placing above the tissue paper another gray scrap of the same degree of brightness, and comparing together the two grays. On neither of them does the contrast-color now appear.

Hering[25] shows clearly that this interpretation is incorrect, and that the disturbing factors are to be otherwise explained. In the first place, the experiment can be so arranged that we could not possibly be deceived into believing that we see the gray through a colored medium. Out of a sheet of gray paper cut strips 5 mm. wide in such a way that there will be alternately an empty space and a bar of gray, both of the same width, the bars being held together by the uncut edges of the gray sheet (thus presenting an appearance like a gridiron). Lay this on a colored background--e.g. green--cover both with transparent paper, and above all put a black frame which covers all the edges, leaving visible only the bars, which are now alternately green and gray. The gray bars appear strongly colored by contrast, although, since they occupy as much space as the green bars, we are not deceived into believing that we see the former through a green medium. The same is true if we weave together into a basket pattern narrow strips of green and gray and cover them with the transparent paper.

Why, then, if it is a true sensation due to physiological causes, and not an error of judgment, which causes the contrast, does the color disappear when the outlines of the gray scrap are traced, enabling us to recognize it as an independent object? In the first place, it does not necessarily do so, as will easily be seen if the experiment is tried. The contrast-color often remains distinctly visible in spite of the black outlines. In the second place, there are many adequate reasons why the effect should be modified. Simultaneous contrast is always strongest at the border-line of the two fields; but a narrow black field now separates the two, and itself by contrast strengthens the whiteness of both original fields, which were already little saturated in color; and on black and on white, contrast-colors show only under the most favorable circumstances. Even weak objective differences in color may be made to disappear by such tracing of outlines, as can be seen if we place on a gray background a scrap of faintly-colored paper, cover it with transparent paper and trace its outlines. Thus we see that it is not the recognition of the contrasting field as an independent object which interferes with its color, but rather a number of entirely explicable physiological disturbances.

The same may be proved in the case of holding above the tissue paper a second gray scrap and comparing it with that underneath. To avoid the disturbances caused by using papers of different brightness, the second scrap should be made exactly like the first by covering the same gray with the same tissue paper, and carefully cutting a piece about 10 mm. square out of both together. To thoroughly guard against successive contrast, which so easily complicates the phenomena, we must carefully prevent all previous excitation of the retina by colored light. This may be done by arranging thus: Place the sheet of tissue paper on a glass pane, which rests on four supports; under the paper put the first gray scrap. By means of a wire, fasten the second gray scrap 2 or 3 cm. above the glass plate. Both scraps appear exactly alike, except at the edges. Gaze now at both scraps, with eyes not exactly accommodated, so that they appear near one another, with a very narrow space between. Shove now a colored field (green) underneath the glass plate, and the contrast appears at once on both scraps. If it appears less clearly on the upper scrap, it is because of its bright and dark edges, its inequalities, its grain, etc. When the accommodation is exact, there is no essential change, although then on the upper scrap the bright edge on the side toward the light, and the dark edge on the shadow side, disturb somewhat. By continued fixation the contrast becomes weaker and finally yields to simultaneous induction, causing the scraps to become indistinguishable from the ground. Remove the green field and both scraps become green, by successive induction. If the eye moves about freely these last-named phenomena do not appear, but the contrast continues indefinitely and becomes stronger. When Helmholtz found that the contrast on the lower scrap disappeared, it was evidently because he then really held the eye fixed. This experiment may be disturbed by holding the upper scrap wrongly and by the differences in brightness of its edges, or by other inequalities, but not by that recognizing of it 'as an independent body lying above the colored ground,' on which the psychological explanation rests.

In like manner the claims of the psychological explanation can be shown to be inadequate in other cases of contrast. Of frequent use are revolving disks, which are especially efficient in showing good contrast-phenomena, because all inequalities of the ground disappear and leave a perfectly homogeneous surface. On a white disk are arranged colored sectors, which are interrupted midway by narrow black fields in such a way that when the disk is revolved the white becomes mixed with the color and the black, forming a colored disk of weak saturation on which appears a gray ring. The latter is colored by contrast with the field which surrounds it. Helmholtz explains the fact thus:

"The difference of the compared colors appears greater than it really
is either because this difference, when it is the only existing one
and draws the attention to itself alone, makes a stronger impression
than when it is one among many, or because the different colors of the
surface are conceived as alterations of the one ground-color of the
surface such as might arise through shadows falling on it, through
colored reflexes, or through mixture with colored paint or dust. In
truth, to produce an objectively gray spot on a green surface, a
reddish coloring would be necessary."[26]

This explanation is easily proved false by painting the disk with narrow green and gray concentric rings, and giving each a different saturation. The contrast appears though there is no ground-color, and no longer a single difference, but many. The facts which Helmholtz brings forward in support of his theory are also easily turned against him. He asserts that if the color of the ground is too intense, or if the gray ring is bordered by black circles, the contrast becomes weaker; that no contrast appears on a white scrap held over the colored field; and that the gray ring when compared with such scrap loses its contrast-color either wholly or in part. Hering points out the inaccuracy of all these claims. Under favorable conditions it is impossible to make the contrast disappear by means of black enclosing lines, although they naturally form a disturbing element; increase in the saturation of the field, if disturbance through increasing brightness-contrast is to be avoided, demands a darker gray field, on which contrast-colors are less easily perceived; and careful use of the white scrap leads to entirely different results. The contrast-color does appear upon it when it is first placed above the colored field; but if it is carefully fixated, the contrast-color diminishes very rapidly both on it and on the ring, from causes already explained. To secure accurate observation, all complication through successive contrast should be avoided thus: first arrange the white scrap, then interpose a gray screen between it and the disk, rest the eye, set the wheel in motion, fixate the scrap, and then have the screen removed. The contrast at once appears clearly, and its disappearance through continued fixation can be accurately watched.

Brief mention of a few other cases of contrast must suffice. The so-called mirror experiment consists of placing at an angle of 45º a green (or otherwise colored) pane of glass, forming an angle with two white surfaces, one horizontal and the other vertical. On each white surface is a black spot. The one on the horizontal surface is seen through the glass and appears dark green, the other is reflected from the surface of the glass to the eye, and appears by contrast red. The experiment may be so arranged that we are not aware of the presence of the green glass, but think that we are looking directly at a surface with green and red spots upon it; in such a case there is no deception of judgment caused by making allowance for the colored medium through which we think that we see the spot, and therefore the psychological explanation does not apply. On excluding successive contrast by fixation the contrast soon disappears as in all similar experiments.[27]

_Colored shadows_ have long been thought to afford a convincing proof of the fact that simultaneous contrast is psychological in its origin. They are formed whenever an opaque object is illuminated from two separate sides by lights of different colors. When the light from one source is white, its shadow is of the color of the other light, and the second shadow is of a color complementary to that of the field illuminated by both lights. If now we take a tube, blackened inside, and through it look at the colored shadow, none of the surrounding field being visible, and then have the colored light removed, the shadow still appears colored, although 'the circumstances which caused it have disappeared.' This is regarded by the psychologists as conclusive evidence that the color is due to deception of judgment. It can, however, easily be shown that the persistence of the color seen through the tube is due to fatigue of the retina through the prevailing light, and that when the colored light is removed the color slowly disappears as the equilibrium of the retina becomes gradually restored. When successive contrast is carefully guarded against, the simultaneous contrast, whether seen directly or through the tube, never lasts for an instant on removal of the colored field. The physiological explanation applies throughout to all the phenomena presented by colored shadows.[28]

If we have a small field whose illumination remains constant, surrounded by a large field of changing brightness, an increase or decrease in brightness of the latter results in a corresponding apparent decrease or increase respectively in the brightness of the former, while the large field seems to be unchanged. Exner says:

"This illusion of sense shows that we are inclined to regard as
constant the dominant brightness in our field of vision, and hence to
refer the changing difference between this and the brightness of a
limited field to a change in brightness of the latter."

The result, however, can be shown to depend not on illusion, but on actual retinal changes, which alter the sensation experienced. The irritability of those portions of the retina lighted by the large field becomes much reduced in consequence of fatigue, so that the increase in brightness becomes much less apparent than it would be without this diminution in irritability. The small field, however, shows the change by a change in the contrast-effect induced upon it by the surrounding parts of the retina.[29]

The above cases show clearly that _physiological processes, and not deception of judgment, are responsible for contrast of color_. To say this, however, is not to maintain that our perception of a color is never in any degree modified by our judgment of what the particular colored thing before us may be. We have unquestionable illusions of color due to wrong inferences as to what object is before us. Thus Von Kries[30] speaks of wandering through evergreen forests covered with snow, and thinking that through the interstices of the boughs he saw the deep blue of pine-clad mountains, covered with snow and lighted by brilliant sunshine; whereas what he really saw was the white snow on trees near by, lying in shadow].[31]

Such a mistake as this is undoubtedly of psychological origin. It is a wrong _classification_ of the appearances, due to the arousal of intricate processes of association amongst which is the suggestion of a different hue from that really before the eyes. In the ensuing chapters such illusions as this will be treated of in considerable detail. But it is a mistake to interpret the simpler cases of contrast in the light of such illusions as these. These illusions can be rectified in an instant, and we then wonder how they could have been. They come from insufficient attention, or from the fact that the impression which we get is a sign of more than one possible object, and can be interpreted in either way. In none of these points do they resemble simple color-contrast, which _unquestionably is a phenomenon of sensation immediately aroused_.

      *       *       *       *       *

I have dwelt upon the facts of color-contrast at such great length because they form so good a text to comment on in my struggle against the view that sensations are immutable psychic things which coexist with higher mental functions. Both sensationalists and intellectualists agree that such sensations exist. They _fuse_, say the pure sensationalists, and _make_ the higher mental function; they _are combined_ by activity of the Thinking Principle, say the intellectualists. I myself have contended that they _do not exist_ in or alongside of the higher mental function when that exists. The things which arouse them exist; and the higher mental function also knows these same things. But just as its knowledge of the things supersedes and displaces their knowledge, so it supersedes and displaces them, when it comes, being as much as they are a direct resultant of whatever momentary brain-conditions may obtain. The psychological theory of contrast, on the other hand, holds the sensations still to exist in themselves unchanged before the mind, whilst the 'relating activity' of the latter deals with them freely and settles to its own satisfaction what each shall be, in view of what the others also are. Wundt says expressly that the Law of Relativity is "not a law of sensation but a law of Apperception;" and the word Apperception connotes with him a higher intellectual spontaneity.[32] This way of taking things belongs with the philosophy that looks at the _data_ of sense as something earth-born and servile, and the 'relating of them together' as something spiritual and free. Lo! the spirit can even change the intrinsic quality of the sensible facts themselves if by so doing it can relate them better to each other! But (apart from the difficulty of seeing how changing the sensations should relate them better) is it not manifest that the relations are part of the 'content' of consciousness, part of the 'object,' just as much as the sensations are? Why ascribe the former exclusively to the _knower_ and the latter to the _known_? The _knower_ is in every case a unique pulse of thought corresponding to a unique reaction of the brain upon its conditions. All that the facts of contrast show us is that the _same real thing_ may give us quite different sensations when the conditions alter, and that we must therefore be careful which one to select as the thing's truest representative.

      *       *       *       *       *

_There are many other facts beside the phenomena of contrast_ which prove that _when two objects act together on us the sensation which either would give alone becomes a different sensation_. A certain amount of skin dipped in hot water gives the perception of a certain heat. More skin immersed makes the heat much more intense, although of course the water's heat is the same. A certain extent as well as intensity, in the quantity of the stimulus is requisite for any quality to be felt. Fick and Wunderli could not distinguish heat from touch when both were applied through a hole in a card, and so confined to a small part of the skin. Similarly there is a _chromatic minimum_ of size in objects. The image they cast on the retina must needs have a certain extent, or it will give no sensation of color at all. Inversely, more intensity in the outward impression may make the subjective object more extensive. This happens, as will be shown in Chapter XIX, when the illumination is increased: The whole room expands and dwindles according as we raise or lower the gas-jet. It is not easy to explain any of these results as illusions of judgment due to the inference of a wrong objective cause for the sensation which we get. No more is this easy in the case of Weber's observation that a thaler laid on the skin of the forehead feels heavier when cold than when warm; or of Szabadföldi's observation that small wooden disks when heated to 122° Fahrenheit often feel heavier than those which are larger but not thus warmed;[33] or of Hall's observation that a heavy point moving over the skin seems to go faster than a lighter one moving at the same rate of speed.[34]

Bleuler and Lehmann some years ago called attention to a strange idiosyncrasy found in some persons, and consisting in the fact that impressions on the eye, skin, etc., were accompanied by distinct sensations of _sound_.[35] _Colored hearing_ is the name sometimes given to the phenomenon, which has now been repeatedly described. Quite lately the Viennese aurist Urbantschitsch has proved that these cases are only extreme examples of a very general law, and that all our sense-organs influence each other's sensations.[36] The hue of patches of color so distant as not to be recognized was immediately, in U.'s patients, perceived when a tuning-fork was sounded close to the ear. Sometimes, on the contrary, the field was darkened by the sound. The acuity of vision was increased, so that letters too far off to be read could be read when the tuning-fork was heard. Urbantschitsch, varying his experiments, found that their results were mutual, and that sounds which were on the limits of audibility became audible when lights of various colors were exhibited to the eye. Smell, taste, touch, sense of temperature, etc., were all found to fluctuate when lights were seen and sounds were heard. Individuals varied much in the degree and kind of effect produced, but almost every one experimented on seems to have been in some way affected. The phenomena remind one somewhat of the 'dynamogenic' effects of sensations upon the strength of muscular contraction observed by M. Féré, and later to be described. The most familiar examples of them seem to be the increase of _pain_ by noise or light, and the increase of _nausea_ by all concomitant sensations. Persons suffering in any way instinctively seek stillness and darkness.

      *       *       *       *       *

Probably every one will agree that the best way of formulating all such facts is physiological: it must be that the cerebral process of the first sensation is reinforced or otherwise altered by the other current which comes in. No one, surely, will prefer a psychological explanation _here_. Well, it seems to me that _all_ cases of mental reaction to a plurality of stimuli must be like these cases, and that the physiological formulation is everywhere the simplest and the best. When simultaneous red and green light make us see yellow, when three notes of the scale make us hear a chord, it is not because the sensations of red and of green and of each of the three notes enter the mind as such, and there 'combine' or 'are combined by its relating activity' into the yellow and the chord, it is because the larger sum of light-waves and of air-waves arouses new cortical processes, to which the yellow and the chord directly correspond. Even when the sensible qualities of things enter into the objects of our highest thinking, it is surely the same. Their several _sensations_ do not continue to exist there tucked away. They are _replaced_ by the higher thought which, although a different psychic unit from them, knows the same sensible qualities which they know.

The principles laid down in Chapter VI seem then to be corroborated in this new connection. _You cannot build up one thought or one sensation out of many; and only direct experiment can inform us of what we shall perceive when we get many stimuli at once._


THE 'ECCENTRIC PROJECTION' OF SENSATIONS.


We often hear the opinion expressed that all our sensations at first appear to us as subjective or internal, and are afterwards and by a special act on our part 'extradited' or 'projected' so as to appear located in an outer world. Thus we read in Professor Ladd's valuable work that

"Sensations... are psychical states _whose place_--so far as they
can be said to have one--_is the mind_. The transference of these
sensations from mere mental states to physical processes located
in the periphery of the body, or to qualities of things projected
in space external to the body, is a mental act. It may rather be
said to be a mental _achievement_ [cf. Cudworth, footnote 10,
as to knowledge being _conquering_], for it is an act which in
its perfection results from a long and intricate process of
development.... Two noteworthy stages, or 'epoch-making' achievements
in the process of elaborating the presentations of sense, require a
special consideration. These are '_localization_,' or the transference
of the composite sensations from mere states of the mind to processes
or conditions recognized as taking place at more or less definitely
fixed points or areas of the body; and '_eccentric projection_'
(sometimes called 'eccentric perception') or the giving to these
sensations an objective existence (in the fullest sense of the word
'objective') as qualities of objects situated within a field of space
and in contact with, or more or less remotely distant from, the
body."[37]

It seems to me that there is not a vestige of evidence for this view. It hangs together with the opinion that our sensations are originally devoid of all spatial content,[38] an opinion which I confess that I am wholly at a loss to understand. As I look at my bookshelf opposite I cannot frame to myself an idea, however imaginary, of any feeling which I could ever possibly have got from it except the feeling of the same big extended sort of outward fact which I now perceive. So far is it from being true that our first way of feeling things is the feeling of them as subjective or mental, that the exact opposite seems rather to be the truth. Our earliest, most instinctive, least developed kind of consciousness is the objective kind; and only as reflection becomes developed do we become aware of an inner world at all. Then indeed we enrich it more and more, even to the point of becoming idealists, with the spoils of the outer world which at first was the only world we knew. But subjective consciousness, aware of itself as subjective, does not at first exist. Even an attack of pain is surely felt at first objectively as something in space which prompts to motor reaction, and to the very end it is located, not in the mind, but in some bodily part.

"A sensation which should not awaken an impulse to move, nor any
tendency to produce an outward effect, would manifestly be useless to
a living creature. On the principles of evolution such a sensation
could never be developed. Therefore every sensation originally refers
to something external and independent of the sentient creature.
Rhizopods (according to Engelmann's observations) retract their
pseudopodia whenever these touch foreign bodies, even if these
foreign bodies are the pseudopodia of other individuals of their
own species, whilst the mutual contact of their own pseudopodia is
followed by no such contraction. These low animals can therefore
already feel an outer world--even in the absence of innate ideas of
causality, and probably without any clear consciousness of space. In
truth the conviction that something exists outside of ourselves does
not come from thought. It comes from sensation; it rests on the same
ground as our conviction of our own existence.... If we consider the
behavior of new-born animals, we never find them betraying that they
are first of all conscious of their sensations as purely subjective
excitements. We far more readily incline to explain the astonishing
certainty with which they make use of their sensations (and which is
an effect of adaptation and inheritance) as the result of an inborn
intuition of the outer world.... Instead of starting from an original
pure subjectivity of sensation, and seeking how this could possibly
have acquired an objective signification, we must, on the contrary,
begin by the possession of objectivity by the sensation and then show
how for reflective consciousness the latter becomes interpreted as an
effect of the object, how in short the original immediate objectivity
becomes changed into a remote one."[39]

Another confusion, much more common than the denial of all objective character to sensations, is the assumption that they are all originally located _inside the body_ and are projected outward by a secondary act. This secondary judgment is always false, according to M. Taine, so far as the place of the sensation itself goes. But it happens to _hit_ a real object which is at the point towards which the sensation is projected; so we may call its result, according to this author, a _veridical hallucination_.[40] The word Sensation, to begin with, is constantly, in psychological literature, used as if it meant one and the same thing with the _physical impression_ either in the terminal organs or in the centres, which is its antecedent condition, and this notwithstanding that by sensation we mean a mental, not a physical, fact. But those who expressly mean by it a mental fact still leave to it a physical _place_, still think of it as objectively inhabiting the very neural tracts which occasion its appearance when they are excited; and then (going a step farther) they think that it must _place itself_ where _they_ place it, or be subjectively sensible of that place as its habitat in the first instance, and afterwards have to be _moved_ so as to appear elsewhere.

All this seems highly confused and unintelligible. Consciousness, as we saw in an earlier chapter (vol. I p. 214) cannot properly be said to _inhabit_ any place. It has dynamic relations with the brain, and cognitive relations with everything and anything. From the one point of view _we_ may say that a sensation is in the same place with the brain (if we like), just as from the other point of view we may say that it is in the same place with whatever quality it may be cognizing. But the supposition that a sensation primitively _feels either itself or its object to be in the same place with the brain_ is absolutely groundless, and neither _a priori_ probability nor facts from experience can be adduced to show that such a deliverance forms any part of the original cognitive function of our sensibility.

Where, then, do we feel the objects of our original sensations to be?

Certainly a child newly born in Boston, who gets a sensation from the candle-flame which lights the bedroom, or from his diaper-pin, does not feel either of these objects to be situated in longitude 72° W. and latitude 41° N. He does not feel them to be in the third story of the house. He does not even feel them in any distinct manner to be to the right or the left of any of the other sensations which he may be getting from other objects in the room at the same time. He does not, in short, know anything _about_ their space-relations to anything else in the world. The flame fills its own place, the pain fills its own place; but as yet these places are neither identified with, nor discriminated from, any other places. That comes later. For the places thus first sensibly known are elements of the child's space-world which remain with him all his life; and by memory and later experience he learns a vast number of things _about_ those places which at first he did not know. But to the end of time certain places of the world remain defined for him as the places _where those sensations were_; and his only possible answer to the question _where anything is_ will be to say '_there_,' and to name some sensation or other like those first ones, which shall identify the spot. Space _means_ but the aggregate of all our possible sensations. There is no duplicate space known _aliunde_, or created by an 'epoch-making achievement' into which our sensations, originally spaceless, are dropped. They _bring_ space and all its places to our intellect, and do not derive it thence.

By his body, then, the child later means simply _that place where_ the pain from the pin, and a lot of other sensations like it, were or are felt. It is no more true to say that he locates that pain in his body, than to say that he locates his body in that pain. Both are true: that pain is part of what he _means by the word body_. Just so by the outer world the child means nothing more than _that place where_ the candle-flame and a lot of other sensations like it are felt. He no more locates the candle in the outer world than he locates the outer world in the candle. Once again, he does both; for the candle is part of what he _means_ by 'outer world.'

      *       *       *       *       *

This (it seems to me) will be admitted, and will (I trust) be made still more plausible in the chapter on the Perception of Space. But the later developments of this perception are so complicated that these simple principles get easily overlooked. One of the complications comes from the fact that things _move_, and that the original object which we feel them to be splits into two parts, one of which remains as their whereabouts and the other goes off as their quality or nature. We then contrast where they _were_ with where they _are_. If _we_ do not move, the sensation of _where they were_ remains unchanged; but we ourselves presently move, so that that also changes; and 'where they were' becomes no longer the actual sensation which it was originally, but a sensation which we merely conceive as possible. Gradually the system of these possible sensations, takes more and more the place of the actual sensations. 'Up' and 'down' become 'subjective' notions; east and west grow more 'correct' than 'right' and 'left' etc.; and things get at last more 'truly' located by their relation to certain ideal fixed co-ordinates than by their relation either to our bodies or to those objects by which their place was originally defined. _Now this revision of our original localizations is a complex affair; and contains some facts which may very naturally come to be described as translocations whereby sensations get shoved farther off than they originally appeared._

Few things indeed are more striking than the changeable distance which the objects of many of our sensations may be made to assume. A fly's humming may be taken for a distant steam-whistle; or the fly itself, seen out of focus, may for a moment give us the illusion of a distant bird. The same things seem much nearer or much farther, according as we look at them through one end or another of an opera-glass. Our whole optical education indeed is largely taken up with assigning their proper distances to the objects of our retinal sensations. An infant will grasp at the moon; later, it is said, he projects that sensation to a distance which he knows to be beyond his reach. In the much quoted case of the 'young gentleman who was born blind,' and who was 'couched' for the cataract by Mr. Chesselden, it is reported of the patient that "when he first saw, he was so far from making any judgment about distances, that he thought all objects whatever touched his eyes (as he expressed it) as what he felt did his skin." And other patients born blind, but relieved by surgical operation, have been described as bringing their hand close to their eyes to feel for the objects which they at first saw, and only gradually stretching out their hand when they found that no contact occurred. Many have concluded from these facts that our earliest visual objects must seem in immediate contact with our eyes.

But tactile objects also may be affected with a like ambiguity of situation.

If one of the hairs of our head be pulled, we are pretty accurately sensible of the direction of the pulling by the movements imparted to the head.[41] But the feeling of the pull is localized, not in that part of the hair's length which the fingers hold, but in the scalp itself. This seems connected with the fact that our hair hardly serves at all as a tactile organ. In creatures with _vibrissæ_, however, and in those quadrupeds whose whiskers are tactile organs, it can hardly be doubted that the feeling is projected out of the root into the shaft of the hair itself. We ourselves have an approach to this when the beard as a whole, or the hair as a whole, is touched. We perceive the contact at some distance from the skin.

When fixed and hard appendages of the body, like the teeth and nails, are touched, we feel the contact where it objectively is, and not deeper in, where the nerve-terminations lie. If, however, the tooth is loose, we feel two contacts, spatially separated, one at its root, one at its top.

From this ease to that of a hard body not organically connected with the surface, but only accidentally in contact with it, the transition is immediate. With the point of a cane we can trace letters in the air or on a wall just as with the finger-tip; and in so doing feel the size and shape of the path described by the cane's tip just as immediately as, without a cane, we should feel the path described by the tip of our finger. Similarly the draughtsman's immediate perception seems to be of the point of his pencil, the surgeon's of the end of his knife, the duellist's of the tip of his rapier as it plunges through his enemy's skin. When on the middle of a vibrating ladder, we feel not only our feet on the round, but the ladder's feet against the ground far below. If we shake a locked iron gate we feel the middle, on which our hands rest, move, but we equally feel the stability of the ends where the hinges and the lock are, and we seem to feel all three at once.[42] And yet the place where the contact is _received_ is in all these cases the skin, whose sensations accordingly are sometimes interpreted as objects on the surface, and at other times as objects a long distance off.

We shall learn in the chapter on Space that our feelings of our own movement are principally due to the sensibility of our rotating _joints_. Sometimes by fixing the attention, say on our elbow-joint, we can feel the movement in the joint itself; but we always are simultaneously conscious of the path which during the movement our finger-tips describe through the air, and yet these same finger-tips themselves are in no way physically modified by the motion. A blow on our ulnar nerve behind the elbow is felt both there and in the fingers. Refrigeration of the elbow produces pain in the fingers. Electric currents passed through nerve-trunks, whether of cutaneous or of more special sensibility (such as the optic nerve), give rise to sensations which are vaguely localized beyond the nerve-tracts traversed. Persons whose legs or arms have been amputated are, as is well known, apt to preserve an illusory feeling of the lost hand or foot being there. Even when they do not have this feeling constantly, it may be occasionally brought back. This sometimes is the result of exciting electrically the nerve-trunks buried in the stump.

"I recently faradized," says Dr. Mitchell, "a case of disarticulated
shoulder without warning my patient of the possible result. For two
years he had altogether ceased to feel the limb. As the current
affected the brachial plexus of nerves he suddenly cried aloud, 'Oh
the hand,--the hand!' and attempted to seize the missing member. The
phantom I had conjured up swiftly disappeared, but no spirit could
have more amazed the man, so real did it seem."[43]

Now the apparent position of the lost extremity varies. Often the foot seems on the ground, or follows the position of the artificial foot, where one is used. Sometimes where the arm is lost the elbow will seem bent, and the hand in a fixed position on the breast. Sometimes, again, the position is non-natural, and the hand will seem to bud straight out of the shoulder, or the foot to be on the same level with the knee of the remaining leg. Sometimes, again, the position is vague; and sometimes it is ambiguous, as in another patient of Dr. Weir Mitchell's who

"lost his leg at the age of eleven, and remembers that the foot by
degrees approached, and at last reached the knee. When he began to
wear an artificial leg it reassumed in time its old position, and he
is never at present aware of the leg as shortened, unless for some
time he talks and thinks of the stump, and of the missing leg, when ...
the direction of attention to the part causes a feeling of discomfort,
and the subjective sensation of active and unpleasant movement of the
toes. With these feelings returns at once the delusion of the foot as
being placed at the knee."

All these facts, and others like them, can easily be described as if our sensations might be induced by circumstances to migrate from their _original locality_ near the brain or near the surface of the body, and to appear farther off; and (under different circumstances) to return again after having migrated. But a little analysis of what happens shows us that this description is inaccurate.

_The objectivity with which each of our sensations originally comes to us, the roomy and spatial character which is a primitive part of its content, is not in the first instance relative to any other sensation._ The first time we open our eyes we get an optical object which is _a place_, but which is not yet _placed_ in relation to any other object, nor identified with any place otherwise known. It is a place with which so far we are only _acquainted_. When later we know that this same place is in 'front' of us, that only means that we have learned something _about_ it, namely, that it is _congruent with that_ _other_ place, called 'front,' which is given us by certain sensations of the arm and hand or of the head and body. But at the first moment of our optical experience, even though we already had an acquaintance with our head, hand, and body, we could not possibly know anything about their relations to this new seen object. It could not be immediately located in respect of _them_. How its place agrees with the places which their feelings yield is a matter of which only later experience can inform us; and in the next chapter we shall see with some detail how later experience does this by means of discrimination, association, selection, and other constantly working functions of the mind. When, therefore, the baby grasps at the moon, that does not mean that what he sees fails to give him the sensation which he afterwards knows as distance; it means only that he has not learned at what _tactile or manual distance_ things which appear at that _visual distance_ are.[44] And when a person just operated for cataract gropes close to his face for far-off objects, that only means the same thing. All the ordinary optical signs of differing distances are absent from the poor creature's sensation anyhow. His vision is monocular (only one eye being operated at a time); the lens is gone, and everything is out of focus; he feels photophobia, lachrymation, and other painful resident sensations of the eyeball itself, whose place he has long since learned to know in tactile terms; what wonder, then, that the first tactile reaction which the new sensations provoke should be one associated with the tactile situation of the organ itself? And as for his assertions about the matter, what wonder, again, if, as Prof. Paul Janet says, they are still expressed in the tactile language which is the only one he knows. "_To be touched_ means for him to receive an impression without first making a movement." His eye gets such an impression now; so he can only say that the objects are 'touching it.'

"All his language, borrowed from touch, but applied to the objects
of his sight, make us think that he perceives differently from
ourselves, whereas, at bottom, it is only his different way of
talking about the same experience."[45]

The other cases of translocation of our sensations are equally easily interpreted without supposing any 'projection' from a centre at which they are originally perceived. Unfortunately the details are intricate; and what I say now can only be made fully clear when we come to the next chapter. We shall then see that we are constantly selecting certain of our sensations as _realities_ and degrading others to the status of _signs_ of these. When we get one of the signs we think of the reality signified; and the strange thing is that then the reality (which need not be itself a sensation at all at the time, but only an idea) is so interesting that it acquires an hallucinatory strength, which may even eclipse that of the relatively uninteresting sign and entirely divert our attention from the latter. Thus the sensations to which our joints give rise when they rotate are signs of what, through a large number of other sensations, tactile and optical, we have come to know as the movement of the whole limb. This movement of the whole limb is what we _think of_ when the joint's nerves are excited in that way; and _its_ place is so much more important than the joint's place that our sense of the latter is taken up, so to speak, into our perception of the former, and the sensation of the movement seems to diffuse itself into our very fingers and toes. But by abstracting our attention from the suggestion of the entire extremity we can perfectly well perceive the same sensation as if it were concentrated in one spot. We can identify it with a differently located tactile and visual image of 'the joint' itself.

Just so when we feel the tip of our cane against the ground. The peculiar sort of movement of the hand (impossible in one direction, but free in every other) which we experience when the tip touches 'the ground,' is a sign to us of the visual and tactile object which we already know under that name. We think of 'the ground' as being there and giving us the sensation of this kind of movement. The sensation, we say, comes _from_ the ground. The ground's place seems to be its place; although at the same time, and for very similar practical reasons, we think of another optical and tactile object, 'the hand' namely, and consider that _its_ place _also_ must be the place of our sensation. In other words, we take an object or sensible content A, and confounding it with another object otherwise known, B, or with two objects otherwise known, B and C, we identify its place with their places. But in all this there is _no 'projecting'_ (such as the extradition-philosophers talk of) of A out of an _original_ place; no primitive location which it first occupied, _away from_ these other sensations, has to be contradicted; no natural 'centre,' from which it is expelled, exists. That would imply that A aboriginally came to us in definite local relations with other sensations, for to be _out_ of B and C is to be in local relation with them as much as to be _in_ them is so. But it was no more out of B and C than it was in them when it first came to us. It simply had nothing to do with them. To say that we feel a sensation's seat to be 'in the brain' or 'against the eye' or 'under the skin' is to say as much _about_ it and to deal with it in as non-primitive a way as to say that it is a mile off. These are all secondary perceptions, ways of defining the sensation's seat _per aliud_. They involve numberless associations, identifications, and imaginations, and admit a great deal of vacillation and uncertainty in the result.[46]

      *       *       *       *       *

_I conclude, then, that there is no truth in the 'eccentric projection' theory_. It is due to the confused assumption that the bodily processes which cause a sensation must also be its seat.[47] But sensations have no seat in this sense. They _become_ seats for each other, as fast as experience associates them together; but that violates no primitive seat possessed by any one of them. And though our sensations cannot then so analyze and talk of themselves, yet at their very first appearance quite as much as at any later date are they cognizant of all those qualities which we end by extracting and conceiving under the names of _objectivity, exteriority,_ and _extent_. It is surely subjectivity and interiority which are the notions _latest_ acquired by the human mind.[48]

      *       *       *       *       *

[1] Some persons will say that we never have a really simple object or content. My definition of sensation does not require the simplicity to be absolutely, but only relatively, extreme. It is worth while in passing, however, to warn the reader against a couple of inferences that are often made. One is that because we gradually learn to analyze so many qualities we ought to conclude that there are no really indecomposable feelings in the mind. The other is that because the processes that produce our sensations are multiple, the sensations regarded as subjective facts must also be compound. To take an example, to a child the taste of lemonade comes at first as a simple quality. He later learns both that many stimuli and many nerves are involved in the exhibition of this taste to his mind, and he also learns to perceive separately the sourness, the coolness, the sweet, the lemon aroma, etc., and the several degrees of strength of each and all of these things,--the experience falling into a large number of aspects, each of which is abstracted, classed, named, etc., and all of which appear to be the elementary sensations into which the original 'lemonade flavor' is decomposed. It is argued from this that the latter never was the simple thing which it seemed. I have already criticised this sort of reasoning in Chapter VI (see pp. 170 ff.). The mind of the child enjoying the simple lemonade flavor and that of the same child grown up and analyzing it are in two entirely different conditions. Subjectively considered, the two states of mind are two altogether distinct sorts of fact. The later mental state says 'this is the _same flavor (or fluid)_ which that earlier state perceived as simple,' but that does not make the two states themselves identical. It is nothing but a case of learning more and more _about_ the same topics of discourse or things.--Many of these topics, however, must be confessed to resist all analysis, the various colors for example. He who sees blue and yellow 'in' a certain green means merely that when green is confronted with these other colors he sees relations of _similarity_. He who sees abstract 'color' in it means merely that he sees a similarity between it and all the other objects known as colors. (Similarity itself cannot ultimately be accounted for by an identical abstract element buried in all the similars, as has been already shown, p. 492 ff.) He who sees abstract paleness, intensity, purity, in the green means other similarities still. These are all outward determinations of that special green, knowledges _about_ it, _zufällige Ansichten_, as Herbart would say, not _elements_ of its composition. Compare the article by Meinong in the Vierteljahrschrift für wiss. Phil., xii. 324.

[2] See Vol. I, p. 221.

[3] Those who wish a fuller treatment than Martin's Human Body affords may be recommended to Bernstein's 'Five Senses of Man,' in the International Scientific Series, or to Ladd's or Wundt's Physiological Psychology. The completest compendium is L. Hermann's Handbuch der Physiologie, vol. iii.

[4] "The sensations which we _postulate_ as the signs or occasions of our perceptions" (A. Seth: Scottish Philosophy, p. 89). "Their existence is _supposed_ only because, without them, it would be impossible to account for the complex phenomena which are directly present in consciousness" (J. Dewey: Psychology, p. 34). Even as great an enemy of Sensation as T. H. Green has to allow it a sort of hypothetical existence under protest. "Perception presupposes feeling" (Contemp. Review, vol. xxxi. p. 747). Cf. also such passages as those in his Prolegomena to Ethics, §§ 48, 49.--Physiologically, the sensory and the reproductive or associative processes may wax and wane independently of each other. Where the part directly due to stimulation of the sense-organ preponderates, the thought has a sensational character, and differs from other thoughts in the sensational direction. Those thoughts which lie farthest in that direction we call _sensations_, for practical convenience, just as we call _conceptions_ those which lie nearer the opposite extreme. But we no more have conceptions pure than we have pure sensations. Our most rarefied intellectual states involve some bodily sensibility, just as our dullest feelings have some intellectual scope. Common-sense and common psychology express this by saying that the mental state is composed of distinct fractional _parts_, one of which is sensation, the other conception. We, however, who believe every mental state to be an integral thing (Vol. I. p. 276) cannot talk thus, but must speak of the degree of sensational or intellectual character, or function, of the mental state. Professor Hering puts, as usual, his finger better upon the truth than any one else. Writing of visual perception, he says: "It is inadmissible in the present state of our knowledge to assert that first and last the same retinal picture arouses exactly the same _pure sensation_, but that this sensation, in consequence of practice and experience, is differently _interpreted_ the last time, and elaborated into a different perception from the first. For the only real _data_ are, on the one hand, the physical picture on the retina,--and that is both times the same; and, on the other hand, the resultant state of consciousness (_ausgeloste Empfindungscomplex_)--and that is both times distinct. _Of any third thing, namely, a pure sensation thrust between the retinal and the mental pictures, we know nothing. We can then, if we wish to avoid all hypothesis, only say that the nervous apparatus reacts upon the same stimulus differently the last time from the first, and that in consequence the consciousness is different too._" (Hermann's Hdbch., iii. i. 567-8.)

[5] Yet even writers like Prof. Bain will deny, in the most gratuitous way, that sensations know anything. "It is evident that the lowest or most restricted form of sensation does not contain an element of knowledge. The mere state of mind called the sensation of scarlet is not knowledge, although a necessary preparation for it." 'Is not knowledge _about_ scarlet' is all that Professor Bain can rightfully say.

[6] By simple ideas of sensation Locke merely means sensations.

[7] Essay c. H. U., bk. ii. ch. xxiii. § 29; ch. xxv. § 9.

[8] _Op. cit_. bk. ii. ch. ii. § 2.

[9] "So far is it from being true that we necessarily have as many feelings in consciousness at one time as there are inlets to the sense then played upon, that it is a fundamental law of pure sensation that each momentary state of the organism yields but one feeling, however numerous may be its parts and its exposures.... To this original Unity of consciousness it makes no difference that the tributaries to the single feeling are beyond the organism instead of within it, in an outside object with several sensible properties, instead of in the living body with its several sensitive functions.... The unity therefore is not made by 'association' of several components; but the plurality is formed by _dissociation_ of unsuspected varieties within the unity; the substantive thing being no product of synthesis, but the residuum of differentiation." (J. Martineau: A Study of Religion (1888), p. 193-4.) Compare also F. H. Bradley, Logic, book i. chap. ii.

[10] Such passages as the following abound in anti-sensationalist literature: "Sense is a kind of dull, confused, and stupid perception obtruded upon the soul from without, whereby it perceives the alterations and motions within its own body, and takes cognizance of individual bodies existing round about it, but does not clearly comprehend what they are nor penetrate into the nature of them, it being intended by nature, as Plotinus speaks, not so properly for _knowledge_ as for the _use of the body_. For the soul suffering under that which it perceives by way of _passion_ cannot master or _Conquer_ it, that is to say, know or understand it. For so Anaxagoras in Aristotle very fitly expresses the nature of knowledge and intellection under the notion of _Conquering_. Wherefore it is necessary, since the mind understands all things, that it should be free from mixture and passion, for this end, as Anaxagoras speaks, that it may be able to _master and conquer_ its objects, that is to say, to _know and understand_ them. In like manner Plotinus, in his book of Sense and Memory, makes to _suffer_ and to _be conquered_ all one, as also to _know_ and to _conquer_; for which reason he concludes that that which suffers doth not know.... Sense that suffers from external objects lies as it were prostrate under them, and is overcome by them.... Sense therefore is a certain kind of drowsy and somnolent perception of that passive part of the soul which is as it were asleep in the body, and acts concretely with it.... It is an energy arising from the body and a certain kind of drowsy or sleeping life of the soul blended together with it. The perceptions of which compound, or of the soul as it were half asleep and half awake, are confused, indistinct, turbid, and encumbered cogitations very different from the energies of the noetical part,... which are free, clear, serene, satisfactory, and awakened cogitations. That is to say, knowledges." Etc., etc., etc. (R. Cudworth: Treatise concerning Eternal and Immutable Morality, bk. iii. chap. ii.) Similarly Malebranche: "THÉODORE.--Oh, oh, Ariste! God knows pain, pleasure, warmth, and the rest. But he does not feel these things. He knows pain, since he knows what that modification of the soul is in which pain consists. He knows it because he alone causes it in us (as I shall presently prove), and he knows what he does. In a word, he knows it because his knowledge has no bounds. But he does not feel it, for if so he would be unhappy. To know pain, then, is not to feel it. ARISTE.--That is true. But to feel it is to know it, is it not? THÉODORE.--No indeed, since God does not feel it in the least, and yet he knows it perfectly. But in order not to quibble about terms, if you will have it that to feel pain is to know it, agree at least that it is not to know it clearly, that it is not to know it by light and by evidence--in a word, that it is not to know its nature; in other words and to speak exactly, it is not to know it at all. To feel pain, for example, is to feel ourselves unhappy without well knowing either what we are or what is this modality of our being which makes us unhappy.... Impose silence on your senses, your imagination, and your passions, and you will hear the pure voice of inner truth, the clear and evident replies of our common master. Never confound the evidence which results from the comparison of ideas with the liveliness of the sensations which touch and thrill you. The livelier our sensations and feelings (_sentiments_) are, the more darkness do they shed. The more terrible or agreeable are our phantoms, and the more body and reality they appear to have, the more dangerous are they and fit to lead us astray." (Entretiens sur la Métaphysique, 3me Entretien, _ad init._) Malebranche's Théodore prudently does not try to explain how God's 'infinite felicity' is compatible with his not feeling joy.

[11] Green: Prolegomena, §§ 20, 28.

[12] Introd. to Hume, §§ 146, 188. It is hard to tell just what this apostolic human being but strenuously feeble writer means by relation. Sometimes it seems to stand for system of related fact. The ubiquity of the 'psychologist's fallacy' (see Vol. I p. 196) in his pages, his incessant leaning on the confusion between the thing known, the thought that knows it, and the farther things known about that thing and about that thought by later and additional thoughts, make it impossible to clear up his meaning. Compare, however, with the utterances in the text such others as these: "The waking of Self-consciousness from the sleep of sense is an absolute new beginning, and nothing can come within the 'crystal sphere' of intelligence except as it is determined by intelligence. What sense is to sense is nothing for thought. What sense is to thought, it is as determined _by_ thought. There can, therefore, be no 'reality' in sensation to which the world of thought can be referred." (Edward Caird's Philosophy of Kant, 1st ed. pp. 393-4.) "When," says Green again, "feeling a pain or pleasure of heat, I perceive it to be connected with the action of approaching the fire, am I not perceiving a relation _of which one constituent, at any rate, is a simple sensation? The true answer is, No._" "Perception, in its simplest form...--perception as the first sight or touch of an object in which nothing but what is seen or touched is recognized--_neither is nor contains sensation_" (Contemp. Rev., xxxi. pp. 746, 750.) "Mere sensation is in truth a phrase that represents no reality." "Mere feeling, then, as a matter unformed by thought, has no place in the world of facts, in the cosmos of possible experience." (Prolegomena to Ethics, §§ 46, 50.)--I have expressed myself a little more fully on this subject in Mind, x. 27 ff.

[13] Stumpf: Tonpsychologie, i. pp. 7, 8. Hobbes's phrase, _sentire semper idem et non sentire ad idem recidunt_, is generally treated as the original statement of the relativity doctrine. J. S. Mill (Examn. of Hamilton, p. 6) and Bain (Senses and Intellect, p. 321; Emotions and Will, pp. 550, 570-2; Logic, i. p. 2; Body and Mind, p. 81) are subscribers to this doctrine. Cf. also J. Mill's Analysis, J. S. Mill's edition, II. 11, 12.

[14] We can steadily hear a note for half an hour. The differences between the senses are marked. Smell and taste seem soon to get fatigued.

[15] In the popular mind it is mixed up with that entirely different doctrine of the 'Relativity of Knowledge' preached by Hamilton and Spencer. This doctrine says that our knowledge is relative _to us_, and is not of the object as the latter is in itself. It has nothing to do with the question which we have been discussing, of whether our objects of knowledge contain absolute terms or consist altogether of relations.

[16] What follows in brackets, as far as p. 27, is from the pen of my friend and pupil Mr. E. B. Delabarre.

[17] These phenomena have close analogues in the phenomena of contrast presented by the temperature-sense (see W. Preyer in Archiv f. d. ges. Phys., Bd. xxv. p. 79 ff.). Successive contrast here is shown in the fact that a warm sensation appears warmer if a cold one has just previously been experienced; and a cold one colder, if the preceding one was warm. If a finger which has been plunged in hot water, and another which has been in cold water, be both immersed in lukewarm water, the same water appears cold to the former finger and warm to the latter. In simultaneous contrast, a sensation of warmth on any part of the skin tends to induce the sensation of cold in its immediate neighborhood; and _vice versâ_. This may be seen if we press with the palm on two metal surfaces of about an inch and a half square and three-fourths inch apart; the skin between them appears distinctly warmer. So also a small object of exactly the temperature of the palm appears warm if a cold object, and cold if a warm object, touch the skin near it.

[18] Helmholtz, Physiolog. Optik, p. 392.

[19] _Loc. cit._ p. 407.

[20] _Loc. cit._ p. 408.

[21] _Loc. cit._ p. 406.

[22] E. Hering, in Hermann's Handbuch d. Physiologie, iii. 1, p. 565.

[23] Hering: 'Zur Lehre vom Lichtsinne.'--Of these experiments the following (found on p. 24 ff.) may be cited as a typical one: "From dark gray paper cut two strips 3-4 cm. long and 1/2 cm. wide, and lay them on a background of which one half is white and the other half deep black, in such a way that one strip lies on each side of the border-line and parallel to it, and at least 1 cm. distant from it. Fixate 1/2 to 1 minute a point on the border-line between the strips. One strip appears much brighter than the other. Close and cover the eyes, and the negative after-image appears.... The difference in brightness of the strips in the after-image is in general much greater than it appeared in direct vision.... This difference in brightness of the strips by no means always increases and decreases with the difference in brightness of the two halves of the background.... A phase occurs in which the difference in brightness of the two halves of the background entirely disappears, and yet both after-images of the strips are still very clear, one of them brighter and one darker than the background, which is equally bright on both halves. Here can no longer be any question of contrast-effect, because the _conditio sine quâ non_ of contrast, namely, the differing brightness of the ground, is no longer present. This proves that the different brightness of the after-images of the strips must have its ground in a different state of excitation of the corresponding portions of the retina, and from this follows further that both these portions of the retina were differently stimulated during the original observation; for the different after-effect demands here a different fore-effect.... In the original arrangement, the objectively similar strips appeared of different brightness, because both corresponding portions of the retina were truly differently excited."

[24] Helmholtz, Physiolog. Optik, p. 407.

[25] In Archiv f. d. ges. Physiol., Bd. xli. §. 1 ff.

[26] Helmholtz, _loc. cit._ p. 412.

[27] See Hering: Archiv f. d. ges. Physiol., Bd. xli. S. 358 ff.

[28] Hering: Archiv f. d. ges. Physiol., Bd. xl. S. 172 ff.; Delabarre: American Journal of Psychology, ii. 636.

[29] Hering: Archiv f. d. ges. Physiol., Bd. xli. S. 91 ff.

[30] Die Gesichtsempfindungen u. ihre Analyse, p. 128.

[31] Mr. Delabarre's contribution ends here.

[32] Physiol. Psych., i. 351, 458-60. The full inanity of the law of relativity is best to be seen in Wundt's treatment, where the great '_allgemeiner Gesetz der Beziehung_,' invoked to account for Weber's law as well as for the phenomena of contrast and many other matters, can only be defined as a tendency _to feel all things in relation to each other_! Bless its little soul! But why does it change the things so, when it thus feels them in relation?

[33] Ladd: Physiol. Psych., p. 348.

[34] Mind, x. 567.

[35] Zwangemässige Lichtempfindung durch Schall (Leipzig, 1881).

[36] Pflüger's Archiv, xlii. 154.

[37] Physiological Psychology, 385, 387. See also such passages as that in Bain; The Senses and the Intellect, pp. 364-6.

[38] "Especially must we avoid all attempts, whether avowed or concealed, to account for the _spatial_ qualities of the presentations of sense by merely describing the qualities of the simple sensations and the modes of their combination. It is position and extension in space which constitutes the very peculiarity of the objects as _no longer_ mere sensations or affections of the mind. As sensations, they are neither _out_ of ourselves nor possessed of the qualities indicated by the word spread-out." (Ladd, _op. cit._ p. 391.)

[39] A. Riehl: Der Philosophischer Kriticismus, Bd. ii. Theil ii. p. 64.

[40] On Intelligence, part ii. bk. ii. chap. ii. §§ vii, viii. Compare such statements as these: "The consequence is that when a sensation has for its usual condition the presence of an object more or less distant from our bodies, and experience has once made us acquainted with this distance, we shall situate our sensation at this distance.--This, in fact, is the case with sensations of hearing and sight. The peripheral extremity of the acoustic nerve is in the deep-seated chamber of the ear. That of the optic nerve is in the most inner recess of the eye. But still, in our present state, we never situate our sensations of sound or color in these places, but without us, and often at a considerable distance from us.... All our sensations of color are thus projected out of our body, and clothe more or less distant objects, furniture, walls, houses, trees, the sky, and the rest. This is why, when we afterwards reflect on them, we cease to attribute them to ourselves; they are alienated and detached from us, so far as to appear different from us. Projected from the nervous surface in which we localize the majority of the others, the tie which connected them to the others and to ourselves is undone.... Thus, all our sensations are wrongly situated, and the red color is no more extended on the arm-chair than the sensation of tingling is situated at my fingers' ends. They are all situated in the sensory centres of the encephalon; all appear situated elsewhere, and a common law allots to each of them its apparent situation." (vol. ii. pp. 47-53.)--Similarly Schopenhauer: "I will now show the same by the sense of sight. The immediate _datum_ is here limited to the sensation of the retina which, it is true, admits of considerable diversity, but at bottom reverts to the impression of light and dark with their shades, and that of colors. This sensation is through and through subjective, that is, inside of the organism and under the skin." (Schopenhauer: Satz vom Grunde, p. 58.) This philosopher then enumerates _seriatim_ what the Intellect does to make the originally subjective sensation objective: 1) it turns it bottom side up; 2) it reduces its doubleness to singleness; 3) it changes its flatness to solidity; and 4) it projects it to a distance from the eye. Again: "_Sensations_ are what we call the impressions on our senses, in so far as they come to our consciousness as states of our own body, especially of our nervous apparatus; we call them _perceptions_ when we form out of them the representation of outer objects." (Helmholtz: Tonempfindungen, 1870, p. 101.)--Once more: "Sensation is always accomplished in the psychic centres, but it manifests itself at the excited part of the periphery. In other words, one is conscious of the phenomenon in the nervous centres,... but one perceives it in the peripheric organs. This phenomenon depends on the experience of the sensations themselves, in which there is a _reflection_ of the subjective phenomenon and a tendency on the part of perception to return as it were to the external cause which has roused the mental state because the latter is connected with the former." (Sergi: Psychologie Physiologique (Paris, 1888), p. 189.)--The clearest and best passage I know is in Liebmann: Der Objective Anblick (1869), pp. 67-72, but it is unfortunately too long to quote.

[41] This is proved by Weber's device of causing the head to be firmly pressed against a support by another person, whereupon the direction of traction ceases to be perceived.

[42] Lotze: Med. Psych., 428-433; Lipps: Grundtatsachen des Seelenlebens, 582.

[43] Injuries to Nerves (Philadelphia, 1872), p. 350 ff.

[44] In reality it probably means only a restless movement of desire, which he might make even after he had become aware of his impotence to touch the object.

[45] Revue Philosophique, vii. p. 1 ff., an admirable critical article, in the course of which M. Janet gives a bibliography of the cases in question. See also Dunan: _ibid._ xxv. 165-7. They are also discussed and similarly interpreted by T. K. Abbot: Sight and Touch (1864), chapter x.

[46] The intermediary and shortened locations of the lost hand and foot in the amputation cases also show this. It is easy to see why the phantom foot might continue to follow the position of the artificial one. But I confess that I cannot explain its half way-positions.

[47] It is from this confused assumption that the time-honored riddle comes, of how, with an upside-down picture on the retina, we can see things right-side up. Our consciousness is _naïvely_ supposed to inhabit the picture and to feel the picture's position as related to other objects of space. But the truth is that the picture is non-existent either as a habitat or as anything else, for immediate consciousness. Our notion of it is an enormously late conception. The outer object is given immediately with all those qualities which later are named and determined in relation to other sensations. The 'bottom' of this object is where we see what by touch we afterwards know as our _feet_, the 'top' is the place in which we see what we know as other people's heads, etc., etc. Berkeley long ago made this matter perfectly clear (see his Essay towards a new Theory of Vision, §§ 93-98, 113-118).

[48] For full justification the reader must see the next chapter. He may object, against the summary account given now, that in a babe's immediate field of vision the various things which appear are located _relatively to each other_ from the outset. I admit that _if discriminated_, they would appear so located. But they are parts of the content of one sensation, not sensations separately experienced, such as the text is concerned with. The fully developed 'world,' in which all our sensations ultimately find location, is nothing but an imaginary object framed after the pattern of the field of vision, by the addition and continuation of one sensation upon another in an orderly and systematic way. In corroboration of my text I must refer to pp. 57-60 of Riehl's book quoted above on page 32, and to Uphues: Wahrnehmung und Empfindung (1888), especially the _Einleitung_ and pp. 51-61.



CHAPTER XVIII.

IMAGINATION.


_Sensations, once experienced, modify the nervous organism, so that copies of them arise again in the mind after the original outward stimulus is gone._ No mental copy, however, can arise in the mind, of any kind of sensation which has never been directly excited from without.

The blind may dream of sights, the deaf of sounds, for years after they have lost their vision or hearing;[49] but the man _born_ deaf can never be made to imagine what sound is like, nor can the man _born_ blind ever have a mental vision. In Locke's words, already quoted, "the mind can frame unto itself no one new simple idea." The originals of them all must have been given from without. Fantasy, or Imagination, are the names given to the faculty of reproducing copies of originals once felt. The imagination is called 'reproductive' when the copies are literal; 'productive' when elements from different originals are recombined so as to make new wholes.

_After-images_ belong to sensation rather than to imagination; so that the most immediate phenomena of imagination would seem to be those tardier images (due to what the Germans call _Sinnesgedächtniss_) which were spoken of in Vol. I, p. 617,--coercive hauntings of the mind by echoes of unusual experiences for hours after the latter have taken place. The phenomena ordinarily ascribed to imagination, however, are those mental pictures of possible sensible experiences, to which the ordinary processes of associative thought give rise.

When represented with surroundings concrete enough to constitute a _date_, these pictures, when they revive, form _recollections_. We have already studied the machinery of recollection in Chapter XVI. When the mental pictures are of data freely combined, and reproducing no past combination exactly, we have acts of imagination properly so called.


OUR IMAGES ARE USUALLY VAGUE.


For the ordinary 'analytic' psychology, each sensibly discernible element of the object imagined is represented by its own separate idea, and the total object is imagined by a 'cluster' or 'gang' of ideas. We have seen abundant reason to reject this view (see Vol. I, p. 276 ff.). An imagined object, however complex, is at any one moment thought in one idea, which is aware of all its qualities together. If I slip into the ordinary way of talking, and speak of various ideas 'combining,' the reader will understand that this is only for popularity and convenience, and he will not construe it into a concession to the atomistic theory in psychology.

Hume was the hero of the atomistic theory. Not only were ideas copies of original impressions made on the sense-organs, but they were, according to him, completely adequate copies, and were all so separate from each other as to possess no manner of connection. Hume proves ideas in the imagination to be completely adequate copies, not by appeal to observation, but by _a priori_ reasoning, as follows:

"The mind cannot form any notion of quantity or quality, without
forming a precise notion of the degrees of each," for "'tis confessed
that no object can appear to the senses; or in other words, that
no impression[50] can become present to the mind, without being
determined in its degrees both of quantity and quality. The confusion
in which impressions are sometimes involved proceeds only from
their faintness and unsteadiness, not from any capacity in the
mind to receive any impression, which in its real existence has no
particular degree nor proportion. That is a contradiction in terms;
and even implies the flattest of all contradictions, _viz._, that
'tis possible for the same thing both to be and not to be. Now since
all ideas are derived from impressions, and are nothing but copies
and representations of them, whatever is true of the one must be
acknowledged concerning the other. Impressions and ideas differ only
in their strength and vivacity. The foregoing conclusion is not
founded on any particular degree of vivacity. It cannot therefore be
affected by any variation in that particular. An idea is a weaker
impression; and as a strong impression must necessarily have a
determinate quantity and quality, the case must be the same with its
copy or representative."[51]

The slightest introspective glance will show to anyone the falsity of this opinion. Hume surely had images of his own works without seeing distinctly every word and letter upon the pages which floated before his mind's eye. His dictum is therefore an exquisite example of the way in which a man will be blinded by _a priori_ theories to the most flagrant facts. It is a rather remarkable thing, too, that the psychologists of Hume's own empiricist school have, as a rule, been more guilty of this blindness than their opponents. The fundamental _facts_ of consciousness have been, on the whole, more accurately reported by the spiritualistic writers. None of Hume's pupils, so far as I know, until Taine and Huxley, ever took the pains to contradict the opinion of their master. Prof. Huxley in his brilliant little work on Hume set the matter straight in the following words:

"When complex impressions or complex ideas are reproduced as memories,
it is probable that the copies never give all the details of the
originals with perfect accuracy, and it is certain that they rarely
do so. No one possesses a memory so good, that if he has only once
observed a natural object, a second inspection does not show him
something that he has forgotten. Almost all, if not all, our memories
are therefore sketches, rather than portraits, of the originals--the
salient features are obvious, while the subordinate characters are
obscure or unrepresented.
"Now, when several complex impressions which are more or less
different from one another--let us say that out of ten impressions
in each, six are the same in all, and four are different from all
the rest--are successively presented to the mind, it is easy to see
what must be the nature of the result. The repetition of the six
similar impressions will strengthen the six corresponding elements of
the complex idea, which will therefore acquire greater vividness;
while the four differing impressions of each will not only acquire no
greater strength than they had at first, but, in accordance with the
law of association, they will all tend to appear at once, and will
thus neutralize one another.
"This mental operation may be rendered comprehensible by considering
what takes place in the formation of compound photographs--when the
images of the faces of six sitters, for example, are each received on
the same photographic plate, for a sixth of the time requisite to take
one portrait. The final result is that all those points in which the
six faces agree are brought out strongly, while all those in which
they differ are left vague; and thus what may be termed a _generic_
portrait of the six, in contradistinction to a _specific_ portrait of
any one, is produced.
"Thus our ideas of single complex impressions are incomplete in one
way, and those of numerous, more or less similar, complex impressions
are incomplete in another way; that is to say, they are _generic_, not
_specific_. And hence it follows that our ideas of the impressions in
question are not, in the strict sense of the word, copies of those
impressions; while, at the same time, they may exist in the mind
independently of language.
"The generic ideas which are formed from several similar, but not
identical, complex experiences are what are called _abstract_ or
_general_ ideas; and Berkeley endeavored to prove that all general
ideas are nothing but particular ideas annexed to a certain term,
which gives them a more extensive signification, and makes them
recall, upon occasion, other individuals which are similar to them.
Hume says that he regards this as 'one of the greatest and the most
valuable discoveries that has been made of late years in the republic
of letters,' and endeavors to confirm it in such a manner that it
shall be 'put beyond all doubt and controversy.'
"I may venture to express a doubt whether he has succeeded in his
object; but the subject is an abstruse one; and I must content myself
with the remark, that though Berkeley's view appears to be largely
applicable to such general ideas as are formed after language has
been acquired, and to all the more abstract sort of conceptions, yet
that general ideas of sensible objects may nevertheless be produced
in the way indicated, and may exist independently of language. In
dreams, one sees houses, trees, and other objects, which are perfectly
recognizable as such, but which remind one of the actual objects as
seen 'out of the corner of the eye,' or of the pictures thrown by a
badly-focussed magic lantern. A man addresses us who is like a figure
seen in twilight; or we travel through countries where every feature
of the scenery is vague; the outlines of the hills are ill-marked, and
the rivers have no defined banks. They are, in short, generic ideas
of many past impressions of men, hills, and rivers. An anatomist who
occupies himself intently with the examination of several specimens
of some new kind of animal, in course of time acquires so vivid a
conception of its form and structure that the idea may take visible
shape and become a sort of waking dream. But the figure which thus
presents itself is generic, not specific. It is no copy of any one
specimen, but, more or less, a mean of the series; and there seems no
reason to doubt that the minds of children before they learn to speak,
and of deaf-mutes, are peopled with similarly generated generic ideas
of sensible objects."[52]

_Are Vague Images 'Abstract Ideas'?_


The only point which I am tempted to criticise in this account is Prof. Huxley's _identification of these generic images with 'abstract or general ideas' in the sense of universal conceptions._ Taine gives the truer view. He writes:

"Some years ago I saw in England, in Kew Gardens, for the first time,
araucarias, and I walked along the beds looking at these strange
plants, with their rigid bark and compact, short, scaly leaves, of
a sombre green, whose abrupt, rough, bristling form cut in upon the
fine softly-lighted turf of the fresh grass-plat. If I now inquire
what this experience has left in me, I find, first, the sensible
representation of an araucaria; in fact, I have been able to describe
almost exactly the form and color of the plant. But there is a
difference between this representation and the former sensations, of
which it is the present echo. The internal semblance, from which I
have just made my description, is vague, and my past sensations were
precise. For, assuredly, each of the araucarias I saw then excited in
me a distinct visual sensation; there are no two absolutely similar
plants in nature; I observed perhaps twenty or thirty araucarias;
without a doubt each one of them differed from the others in size, in
girth, by the more or less obtuse angles of its branches, by the more
or less abrupt jutting out of its scales, by the style of its texture;
consequently, my twenty or thirty visual sensations were different.
But no one of these sensations has completely survived in its echo;
the twenty or thirty revivals have blunted one another; thus upset and
agglutinated by their resemblance they are confounded together, and
my present representation is their residue only. This is the product,
or rather the fragment, which is deposited in us, when we have gone
through a series of similar facts or individuals. Of our numerous
experiences there remain on the following day four or five more or
less distinct recollections, which, obliterated themselves, leave
behind in us a simple colorless, vague representation, into which
enter as components various reviving sensations, in an utterly feeble,
incomplete, and abortive state.--_But this representation is not the
general and abstract idea. It is but its accompaniment,_ and, if I may
say so, the ore from which it is extracted. For the representation,
though badly sketched, is a sketch, the sensible sketch of a distinct
individual.... But my abstract idea corresponds to the whole class; it
differs, then, from the representation of an individual.--Moreover, my
abstract idea is perfectly clear and determinate; now that I possess
it, I never fail to recognize an araucaria among the various plants
which may be shown me; it differs then from the confused and floating
representation I have of some particular araucaria."[53]

In other words, a blurred picture is just as much a single mental fact as a sharp picture is; and _the use of either picture by the mind to symbolize a whole class of individuals is a new mental function,_ requiring some other modification of consciousness than the mere perception that the picture is distinct or not. I may bewail the indistinctness of my mental image of my absent friend. That does not prevent my thought from meaning _him_ alone, however. And I may mean all mankind, with perhaps a very sharp image of one man in my mind's eye. The meaning is a function of the more 'transitive' parts of consciousness, the 'fringe' of relations which we feel surrounding the image, be the latter sharp or dim. This was explained in a previous place (see Vol. I, p. 473 ff., especially the note to page 477), and I would not touch upon the matter at all here but for its historical interest.

Our ideas or images of past sensible experiences may then be either distinct and adequate or dim, blurred, and incomplete. It is likely that the different degrees in which different men are able to make them sharp and complete has had something to do with keeping up such philosophic disputes as that of Berkeley with Locke over abstract ideas. Locke had spoken of our possessing 'the general idea of a triangle' which "must be neither oblique nor rectangle, neither equilateral, equicrural, nor scalenon, but all and none of these at once." Berkeley says:

"If any man has the faculty of framing in his mind such an idea of a
triangle as is here described, it is in vain to pretend to dispute him
out of it, nor would I go about it. All I desire is that the reader
would fully and certainly inform himself whether _he_ has such an idea
or no."[54]

Until very recent years it was supposed by all philosophers that there was a typical human mind which all individual minds were like, and that propositions of universal validity could be laid down about such faculties as 'the Imagination.' Lately, however, a mass of revelations have poured in, which make us see how false a view this is. There are imaginations, not 'the Imagination,' and they must be studied in detail.


INDIVIDUALS DIFFER IN IMAGINATION.


The first breaker of ground in this direction was Fechner, in 1860. Fechner was gifted with unusual talent for subjective observation, and in chapter xliv of his 'Psychophysik' he gave the results of a most careful comparison of his own optical after-images, with his optical memory-pictures, together with accounts by several other individuals of their optical memory-pictures.[55] The result was to show a great personal diversity. "It would be interesting," he writes, "to work up the subject statistically; and I regret that other occupations have kept me from fulfilling my earlier intention to proceed in this way."

Flechner's intention was independently executed by Mr. Galton, the publication of whose results in 1880 may be said to have made an era in descriptive Psychology.

"It is not necessary," says Galton, "to trouble the reader with my
early tentative steps. After the inquiry had been fairly started it
took the form of submitting a certain number of printed questions to a
large number of persons. There is hardly any more difficult task than
that of framing questions which are not likely to be misunderstood,
which admit of easy reply, and which cover the ground of inquiry. I
did my best in these respects, without forgetting the most important
part of all--namely, to tempt my correspondents to write freely in
fuller explanation of their replies, and on cognate topics as well.
These separate letters have proved more instructive and interesting by
far than the replies to the set questions.
"The first group of the rather long series of queries related to the
illumination, definition, and coloring of the mental image, and were
framed thus:
"'Before addressing yourself to any of the Questions on the
opposite page, think of some definite object--suppose it is your
breakfast-table as you sat down to it this morning--and consider
carefully the picture that rises before your mind's eye.
"'1. _Illumination._--Is the image dim or fairly clear? Is its
brightness comparable to that of the actual scene?
"'2. _Definition._--Are all the objects pretty well defined at the
same time, or is the place of sharpest definition at any one moment
more contracted than it is in a real scene?
"'3. _Coloring._--Are the colors of the china, of the toast,
bread-crust, mustard, meat, parsley, or whatever may have been on the
table, quite distinct and natural?'
"The earliest results of my inquiry amazed me. I had begun by
questioning friends in the scientific world, as they were the most
likely class of men to give accurate answers concerning this faculty
of visualizing, to which novelists and poets continually allude,
which has left an abiding mark on the vocabularies of every language,
and which supplies the material out of which dreams and the well-known
hallucinations of sick people are built.
"To my astonishment, I found that _the great majority of the men of
science to whom I first applied protested that mental imagery was
unknown to them,_ and they looked on me as fanciful and fantastic
in supposing that the words 'mental imagery' really expressed what
I believed everybody supposed them to mean. They had no more notion
of its true nature than a color-blind man, who has not discerned his
defect, has of the nature of color. They had a mental deficiency of
which they were unaware, and naturally enough supposed that those who
affirmed they possessed it were romancing. To illustrate their mental
attitude it will be sufficient to quote a few lines from the letter of
one of my correspondents, who writes:
"'These questions presuppose assent to some sort of a proposition
regarding the "mind's eye," and the "images" which it sees.... This
points to some initial fallacy.... It is only by a figure of speech
that I can describe my recollection of a scene as a "mental image"
which I can "see" with my "mind's eye."... I do not see it... any
more than a man sees the thousand lines of Sophocles which under due
pressure he is ready to repeat. The memory possesses it,' etc.
"Much the same result followed inquiries made for me by a friend among
members of the French Institute.
"On the other hand, when I spoke to persons whom I met _in general
society_, I found an entirely different disposition to prevail.
_Many men and a yet larger number of women, and many boys and girls,
declared that they habitually saw mental imagery, and that it was
perfectly distinct to them and full of color._ The more I pressed and
crossed-questioned them, professing myself to be incredulous, the
more obvious was the truth of their first assertions. They described
their imagery in minute detail, and they spoke in a tone of surprise
at my apparent hesitation in accepting what they said. I felt that I
myself should have spoken exactly as they did if I had been describing
a scene that lay before my eyes, in broad daylight, to a blind man
who persisted in doubting the reality of vision. Reassured by this
happier experience, I recommenced to inquire among scientific men,
and soon found scattered instances of what I sought, though in by no
means the same abundance as elsewhere. I then circulated my questions
more generally among my friends and through their hands, and obtained
replies... from persons of both sexes, and of various ages, and in the
end from occasional correspondents in nearly every civilized country.
"I have also received batches of answers from various educational
establishments both in England and America, which were made after
the masters had fully explained the meaning of the questions, and
interested the boys in them. These have the merit of returns derived
from a general census, which my other data lack, because I cannot
for a moment suppose that the writers of the latter are a haphazard
proportion of those to whom they were sent. Indeed I know of some
who, disavowing all possession of the power, and of many others who,
possessing it in too faint a degree to enable them to express what
their experiences really were, in a manner satisfactory to themselves,
sent no returns at all. Considerable statistical similarity was,
however, observed between the sets of returns furnished by the
schoolboys and those sent by my separate correspondents, and I may
add that they accord in this respect with the oral information I have
elsewhere obtained. The conformity of replies from so many different
sources which was clear from the first, the fact of their apparent
trustworthiness being on the whole much increased by cross-examination
(though I could give one or two amusing instances of break-down),
and the evident effort made to give accurate answers, have convinced
me that it is a much easier matter than I had anticipated to obtain
trustworthy replies to psychological questions. Many persons,
especially women and intelligent children, take pleasure in
introspection, and strive their very best to explain their mental
processes. I think that a delight in self-dissection must be a strong
ingredient in the pleasure that many are said to take in confessing
themselves to priests.
"Here, then, are two rather notable results: the one is the proved
facility of obtaining statistical insight into the processes of other
persons' minds, whatever _a priori_ objection may have been made
as to its possibility; and the other is that scientific men, as a
class, have feeble powers of visual representation. There is no doubt
whatever on the latter point, however it may be accounted for. My own
conclusion is that an over-ready perception of sharp mental pictures
is antagonistic to the acquirement of habits of highly-generalized
and abstract thought, especially when the steps of reasoning are
carried on by words as symbols, and that if the faculty of seeing the
pictures was ever possessed by men who think hard, it is very apt
to be lost by disuse. The highest minds are probably those in which
it is not lost, but subordinated, and is ready for use on suitable
occasions. I am, however, bound to say that the missing faculty seems
to be replaced so serviceably by other modes of conception, chiefly,
I believe, connected with the incipient motor sense, not of the
eyeballs only but of the muscles generally, that _men who declare
themselves entirely deficient in the power of seeing mental pictures
can nevertheless give lifelike descriptions_ of what they have seen,
and can otherwise express themselves as if they were gifted with a
vivid visual imagination. _They can also become painters of the rank
of Royal Academicians...._[56]
"It is a mistake to suppose that sharp sight is accompanied by
clear visual memory. I have not a few instances in which the
independence of the two faculties is emphatically commented on; and
I have at least one clear case where great interest in outlines and
accurate appreciation of straightness, squareness, and the like, is
unaccompanied by the power of visualizing. Neither does the faculty go
with dreaming. I have cases where it is powerful, and at the same time
where dreams are rare and faint or altogether absent. One friend tells
me that his dreams have not the hundredth part of the vigor of his
waking fancies.
"The visualizing and the identifying powers are by no means
necessarily combined. A distinguished writer on metaphysical topics
assures me that he is exceptionally quick at recognizing a face that
he has seen before, but that he cannot call up a mental image of any
face with clearness.
"Some persons have the power of combining in a single perception more
than can be seen at any one moment by the two eyes....
"I find that a few persons can, by what they often describe as a kind
of touch-sight, visualize at the same moment all round the image of
a solid body. Many can do so nearly, but not altogether round that
of a terrestrial globe. An eminent mineralogist assures me that he
is able to imagine simultaneously all the sides of a crystal with
which he is familiar. I may be allowed to quote a curious faculty
of my own in respect to this. It is exercised only occasionally and
in dreams, or rather in nightmares, but under those circumstances
I am perfectly conscious of embracing an entire sphere in a single
perception. It appears to lie within my mental eyeball, and to be
viewed centripetally.
"This power of comprehension is practically attained in many cases
by indirect methods. It is a common feat to take in the whole
surroundings of an imagined room with such a rapid mental sweep as to
leave some doubt whether it has not been viewed simultaneously. Some
persons have the habit of viewing objects as though they were partly
transparent; thus, if they so dispose a globe in their imagination as
to see both its north and south poles at the same time, they will not
be able to see its equatorial parts. They can also perceive all the
rooms of an imaginary house by a single mental glance, the walls and
floors being as if made of glass. A fourth class of persons have the
habit of recalling scenes, not from the point of view whence they were
observed, but from a distance, and they visualize their own selves as
actors on the mental stage. By one or other of these ways, the power
of seeing the whole of an object, and not merely one aspect of it, is
possessed by many persons.
"The place where the image appears to lie differs much. Most persons
see it in an indefinable sort of way, others see it in front of the
eye, others at a distance corresponding to reality. There exists a
power which is rare naturally, but can, I believe, be acquired without
much difficulty, of projecting a mental picture upon a piece of paper,
and of holding it fast there, so that it can be outlined with a
pencil. To this I shall recur.
"Images usually do not become stronger by dwelling on them; the first
idea is commonly the most vigorous, but this is not always the case.
Sometimes the mental view of a locality is inseparably connected with
the sense of its position as regards the points of the compass, real
or imaginary. I have received full and curious descriptions from very
different sources of this strong geographical tendency, and in one or
two cases I have reason to think it allied to a considerable faculty
of geographical comprehension.
"The power of visualizing is higher in the female sex than in the
male, and is somewhat, but not much, higher in public-school boys than
in men. After maturity is reached, the further advance of age does
not seem to dim the faculty, but rather the reverse, judging from
numerous statements to that effect; but advancing years are sometimes
accompanied by a growing habit of hard abstract thinking, and in
these cases--not uncommon among those whom I have questioned--the
faculty undoubtedly becomes impaired. There is reason to believe that
it is very high in some young children, who seem to spend years of
difficulty in distinguishing between the subjective and objective
world. Language and book-learning certainly tend to dull it.
"The visualizing faculty is a natural gift, and, like all natural
gifts, has a tendency to be inherited. In this faculty the tendency to
inheritance is exceptionally strong, as I have abundant evidence to
prove, especially in respect to certain rather rare peculiarities,...
which, when they exist at all, are usually found among two, three, or
more brothers and sisters, parents, children, uncles and aunts, and
cousins.
"Since families differ so much in respect to this gift, we may suppose
that races would also differ, and there can be no doubt that such
is the case. I hardly like to refer to civilized nations, because
their natural faculties are too much modified by education to allow
of their being appraised in an off-hand fashion. I may, however,
speak of the French, who appear to possess the visualizing faculty
in a high degree. The peculiar ability they show in prearranging
ceremonials and _fêtes_ of all kinds, and their undoubted genius for
tactics and strategy, show that they are able to foresee effects with
unusual clearness. Their ingenuity in all technical contrivances is an
additional testimony in the same direction, and so is their singular
clearness of expression. Their phrase 'figurez-vous,' or 'picture to
yourself,' seems to express their dominant mode of perception. Our
equivalent of 'imagine' is ambiguous.
      *       *       *       *       *
"I have many cases of persons mentally reading off scores when
playing the pianoforte, or manuscript when they are making speeches.
One statesman has assured me that a certain hesitation in utterance
which he has at times is due to his being plagued by the image of
his manuscript speech with its original erasures and corrections. He
cannot lay the ghost, and he puzzles in trying to decipher it.
"Some few persons see mentally in print every word that is uttered;
they attend to the visual equivalent and not to the sound of the
words, and they read them off usually as from a long imaginary strip
of paper, such as is unwound from telegraphic instruments."

The reader will find further details in Mr. Galton's 'Inquiries into Human Faculty,' pp. 83-114.[57] I have myself for many years collected from each and all of my psychology-students descriptions of their own visual imagination; and found (together with some curious idiosyncrasies) corroboration of all the variations which Mr. Galton reports. As examples, I subjoin extracts from two cases near the ends of the scale. The writers are first cousins, grandsons of a distinguished man of science. The one who is a good visualizer says:

"This morning's breakfast-table is both dim and bright; it is dim if
I try to think of it when my eyes are open upon any object; it is
perfectly clear and bright if I think of it with my eyes closed.--All
the objects are clear at once, yet when I confine my attention to any
one object it becomes far more distinct.--I have more power to recall
color than any other one thing: if, for example, I were to recall a
plate decorated with flowers I could reproduce in a drawing the exact
tone, etc. The color of anything that was on the table is perfectly
vivid.--There is very little limitation to the extent of my images:
I can see all four sides of a room, I can see all four sides of two,
three, four, even more rooms with such distinctness that if you should
ask me what was in any particular place in any one, or ask me to count
the chairs, etc., I could do it without the least hesitation.--The
more I learn by heart the more clearly do I see images of my pages.
Even before I can recite the lines I see them so that I could give
them very slowly word for word, but my mind is so occupied in looking
at my printed image that I have no idea of what I am saying, of the
sense of it, etc. When I first found myself doing this I used to think
it was merely because I knew the lines imperfectly; but I have quite
convinced myself that I really do see an image. The strongest proof
that such is really the fact is, I think, the following:
"I can look down the mentally seen page and see the words that
_commence_ all the lines, and from any one of these words I can
continue the line. I find this much easier to do if the words begin
in a straight line than if there are breaks. Example:
   _Étant fait...._
   _Tous...._
   _A des...._
   _Que fit...._
   _Céres...._
       _Avec...._
   _Un fleur...._
       _Comme...._
   (_La Fontaine_ 8. iv.)"

The poor visualizer says:

"My ability to form mental images seems, from what I have studied of
other people's images, to be defective, and somewhat peculiar. The
process by which I seem to remember any particular event is not by
a series of distinct images, but a sort of panorama, the faintest
impressions of which are perceptible through a thick fog.--I cannot
shut my eyes and get a distinct image of anyone, although I used to
be able to a few years ago, and the faculty seems to have gradually
slipped away.--In my most vivid dreams, where the events appear like
the most real facts, I am often troubled with a dimness of sight which
causes the images to appear indistinct.--To come to the question of
the breakfast-table, there is nothing definite about it. Everything
is vague. I cannot say _what_ I see. I could not possibly count the
chairs, but I happen to know that there are ten. I see nothing in
detail.--The chief thing is a general impression that I cannot tell
exactly what I do see. The coloring is about the same, as far as I can
recall it, only very much washed out. Perhaps the only color I can see
at all distinctly is that of the table-cloth, and I could probably see
the color of the wall-paper if I could remember what color it was."

A person whose visual imagination is strong finds it hard to understand how those who are without the faculty can think at all. _Some people undoubtedly have no visual images at all worthy of the name,_[58] and instead of _seeing_ their breakfast-table, they tell you that they _remember_ it or _know_ what was on it. This knowing and remembering takes place undoubtedly by means of verbal images, as was explained already in Chapter IX, pp. 265-6.

      *       *       *       *       *

_The study of Aphasia_ (see Vol. I, p. 54) _has of late years shown how unexpectedly great are the differences between individuals in respect of imagination._ And at the same time the discrepancies between lesion and symptom in different cases of the disease have been largely cleared up. In some individuals the habitual 'thought-stuff,' if one may so call it, is visual; in others it is auditory, articulatory, or motor; in most, perhaps, it is evenly mixed. The same local cerebral injury must needs work different practical results in persons who differ in this way. In one it will throw a much-used brain-tract out of gear; in the other it may affect an unimportant region. A particularly instructive case was published by Charcot in 1883.[59] The patient was

Mr. X., a merchant, born in Vienna, highly educated, master of German,
Spanish, French, Greek, and Latin. Up to the beginning of the malady
which took him to Professor Charcot, he read Homer at sight. He
could, starting from any verse out of the first book of the Iliad,
repeat the following verses without hesitating, by heart. Virgil
and Horace were familiar. He also knew enough of modern Greek for
business purposes. Up to within a year (from the time Charcot saw
him) he enjoyed an exceptional _visual_ memory. He no sooner thought
of persons or things, but features, forms, and colors arose with the
same clearness, sharpness, and accuracy as if the objects stood before
him. When he tried to recall a fact or a figure in his voluminous
polyglot correspondence, the letters themselves appeared before him
with their entire content, irregularities, erasures and all. At school
he recited from a mentally seen page which he read off line by line
and letter by letter. In making computations, he ran his mental eye
down imaginary columns of figures, and performed in this way the most
varied operations of arithmetic. He could never think of a passage in
a play without the entire scene, stage, actors, and audience appearing
to him. He had been a great traveller. Being a good draughtsman, he
used to sketch views which pleased him; and his memory always brought
back the entire landscape exactly. If he thought of a conversation, a
saying, an engagement, the place, the people, the entire scene rose
before his mind.
His _auditory memory_ was always deficient, or at least secondary. He
had no taste for music.
A year and a half previous to examination, after business-anxieties,
loss of sleep, appetite, etc., he noticed suddenly one day an
extraordinary change in himself. After complete confusion, there came
a violent contrast between his old and his new state. Everything about
him seemed so new and foreign that at first he thought he must be
going mad. He was nervous and irritable. Although he saw all things
distinct, he had entirely lost his memory for forms and colors. On
ascertaining this, he became reassured as to his sanity. He soon
discovered that he could carry on his affairs by using his memory in
an altogether new way. He can now describe clearly the difference
between his two conditions.
Every time he returns to A., from which place business often calls
him, he seems to himself as if entering a strange city. He views the
monuments, houses, and streets with the same surprise as if he saw
them for the first time. Gradually, however, his memory returns, and
he finds himself at home again. When asked to describe the principal
public place of the town, he answered, "I know that it is there, but
it is impossible to imagine it, and I can tell you nothing about it."
He has often drawn the port of A. To-day he vainly tries to trace its
principal outlines. Asked to draw a minaret, he reflects, says it is a
square tower, and draws, rudely, four lines, one for ground, one for
top, and two for sides. Asked to draw an arcade, he says, "I remember
that it contains semi-circular arches, and that two of them meeting
at an angle make a vault, but how it _looks_ I am absolutely unable
to imagine." The profile of a man which he drew by request was as if
drawn by a little child; and yet he confessed that he had been helped
to draw it by looking at the bystanders. Similarly he drew a shapeless
scribble for a tree.
He can no more remember his wife's and children's faces than he can
remember the port of A. Even after being with them some time they seem
unusual to him. He forgets his own face, and once spoke to his image
in a mirror, taking it for a stranger. He complains of his loss of
feeling for colors. "My wife has black hair, this I know; but I can no
more recall its color than I can her person and features." This visual
amnesia extends to dating objects from his childhood's years--paternal
mansion, etc., forgotten.
No other disturbances but this loss of visual images. Now when he
seeks something in his correspondence, he must rummage among the
letters like other men, until he meets the passage. He can recall
only the first few verses of the Iliad, and must _grope_ to read
Homer, Virgil, and Horace. Figures which he adds he must now whisper
to himself. He realises clearly that he must help his memory out with
auditory images, which he does with effort. _The words and expressions
which he recalls seem now to echo in his ear, an altogether novel
sensation for him._ If he wishes to learn by heart anything, a series
of phrases for example, he must _read them several times aloud_, so as
to impress his ear. When later he repeats the thing in question, the
sensation of inward hearing which precedes articulation rises up in
his mind. This feeling was formerly unknown to him. He speaks French
fluently; but affirms that he can no longer think in French; but must
get his French words by translating them from Spanish or German, the
languages of his childhood. He dreams no more in visual terms, but
only in words, usually Spanish words. A certain degree of verbal
blindness affects him--he is troubled by the Greek alphabet, etc.[60]

If this patient had possessed the auditory type of imagination from the start, it is evident that the injury, whatever it was, to his centres for optical imagination, would have affected his practical life much less profoundly.

"_The auditory type_," says M. A. Binet,[61] "_appears to be rarer
than the visual._ Persons of this type imagine what they think of in
the language of sound. In order to remember a lesson they impress upon
their mind, not the look of the page, but the sound of the words. They
reason, as well as remember, by ear. In performing a mental addition
they repeat verbally the names of the figures, and add, as it were,
the sounds, without any thought of the graphic signs. Imagination
also takes the auditory form. 'When I write a scene,' said Legouvé to
Scribe, 'I _hear_; but you _see_. In each phrase which I write, the
voice of the personage who speaks strikes my ear. _Vous, qui êtes le
théâtre même_, your actors walk, gesticulate before your eyes; I am
a _listener_, you a _spectator_.'--'Nothing more true,' said Scribe;
'do you know where I am when I write a piece? In the middle of the
parterre.' It is clear that the _pure audile_, seeking to develop only
a single one of his faculties, may, like the pure visualizer, perform
astounding feats of memory--Mozart, for example, noting from memory
the _Miserere_ of the Sistine Chapel after two hearings; the deaf
Beethoven, composing and inwardly repeating his enormous symphonies.
On the other hand, the man of auditory type, like the visual, is
exposed to serious dangers; for if he lose his auditory images, he is
without resource and breaks down completely.
"It is possible that persons with hallucinations of hearing, and
individuals afflicted with the mania that they are victims of
persecution, may all belong to the auditory type; and that the
predominance of a certain kind of imagination may predispose to a
certain order of hallucinations, and perhaps of delirium.
      *       *       *       *       *
"The _motor type_ remains--perhaps the most interesting of all, and
certainly the one of which least is known. Persons who belong to this
type [_les moteurs_, in French, _motiles_, as Mr. Galton proposes to
call them in English] make use, in memory, reasoning, and all their
intellectual operations, of images derived from movement. In order to
understand this important point, it is enough to remember that 'all
our perceptions, and in particular the important ones, those of sight
and touch, contain as integral elements the movements of our eyes and
limbs; and that, if movement is ever an essential factor in our really
seeing an object, it must be an equally essential factor when we see
the same object in imagination' (Ribot).[62] For example, the complex
impression of a ball, which is there, in our hand, is the resultant
of optical impressions of touch, of muscular adjustments of the eye,
of the movements of our fingers, and of the muscular sensations which
these yield. When we imagine the ball, its idea must include the
images of these muscular sensations, just as it includes those of the
retinal and epidermal sensations. They form so many _motor images_.
If they were not earlier recognized to exist, that is because our
knowledge of the muscular sense is relatively so recent. In older
psychologies it never was mentioned, the number of senses being
restricted to five.
"There are persons who remember a drawing better when they have
followed its outlines with their finger. Lecoq de Boisbaudran used
this means in his artistic teaching, in order to accustom his pupils
to draw from memory. He made them follow the outlines of figures with
a pencil held in the air, forcing them thus to associate muscular with
visual memory. Galton quotes a curious corroborative fact. Colonel
Moncrieff often observed in North America young Indians who, visiting
occasionally his quarters, interested themselves greatly in the
engravings which were shown them. One of them followed with care with
the point of his knife the outline of a drawing in the Illustrated
London News, saying that this was to enable him to carve it out the
better on his return home. In this ease the motor images were to
reinforce the visual ones. The young savage was a _motor_....[63]
When one's motor images are destroyed, one loses one's remembrance of
movements, and sometimes, more curiously still, one loses the power
of executing them. Pathology gives us examples in motor aphasia,
agraphia, etc. Take the case of agraphia. An educated man, knowing how
to write, suddenly loses this power, as a result of cerebral injury.
His hand and arm are in no way paralytic, yet he cannot write. Whence
this loss of power? He tells us himself: he no longer knows how. He
has forgotten how to set about it to trace the letters, he has lost
the memory of the movements to be executed, he has no longer the motor
images which, when formerly he wrote, directed his hand.... Other
patients, affected with word-blindness, resort to these motor images
precisely to make amends for their other deficiency.... An individual
affected in this way cannot read letters which are placed before his
eyes, even although his sight be good enough for the purpose. This
loss of the power of reading by sight may, at a certain time, be the
only trouble the patient has. Individuals thus mutilated succeed in
reading by an ingenious roundabout way which they often discover
themselves: it is enough that they should trace the letters with their
finger to understand their sense. What happens in such a case? How can
the hand supply the place of the eye? The motor image gives the key to
the problem. If the patient can read, so to speak, with his fingers,
it is because in tracing the letters he gives himself a certain number
of muscular impressions which are those of writing. In one word,
the patient reads by writing (Charcot): the feeling of the graphic
movements suggests the sense of what is being written as well as sight
would."[64]

The imagination of a blind-deaf mute like Laura Bridgman must be confined entirely to tactile and motor material. _All blind persons must belong to the 'tactile' and 'motile' types_ of the French authors. When the young man whose cataracts were removed by Dr. Franz was shown different geometric figures, he said he "had not been able to form from them the idea of a square and a disk until he perceived a sensation of what he saw in the points of his fingers, as if he really touched the objects."[65]

Professor Stricker of Vienna, who seems to have the motile form of imagination developed in unusual strength, has given a very careful analysis of his own case in a couple of monographs with which all students should become familiar.[66] His recollections both of his own movements and of those of other things are accompanied invariably by distinct muscular feelings in those parts of his body which would naturally be used in effecting or in following the movement. In thinking of a soldier marching, for example, it is as if he were helping the image to march by marching himself in his rear. And if he suppresses this sympathetic feeling in his own legs, and concentrates all his attention on the imagined soldier, the latter becomes, as it were, paralyzed. In general his imagined movements, of whatsoever objects, seem paralyzed the moment no feelings of movement either in his own eyes or in his own limbs accompany them.[67] The movements of articulate speech play a predominant part in his mental life.

"When after my experimental work I proceed to its description, as
a rule I reproduce in the first instance only words, which I had
already associated with the perception of the various details of the
observation whilst the latter was going on. For speech plays in all my
observing so important a part that I ordinarily clothe phenomena in
words as fast as I observe them."[68]

Most persons, on being asked _in what sort of terms they imagine words_, will say 'in terms of hearing.' It is not until their attention is expressly drawn to the point that they find it difficult to say whether auditory images or motor images connected with the organs of articulation predominate. A good way of bringing the difficulty to consciousness is that proposed by Stricker: Partly open your mouth and then imagine any word with labials or dentals in it, such as 'bubble, 'toddle.' Is your image under these conditions distinct? To most people the image is at first 'thick,' as the sound of the word would be if they tried to pronounce it with the lips parted. Many can never imagine the words clearly with the mouth open; others succeed after a few preliminary trials. The experiment proves how dependent our verbal imagination is on actual feelings in lips, tongue, throat, larynx, etc.

"When we recall the impression of a word or sentence, if we do not
speak it out, we feel the twitter of the organs just about to come
to that point. The articulating parts--the larynx, the tongue, the
lips--are all sensibly excited; a _suppressed articulation is in fact
the material of our recollection_, the intellectual manifestation, the
_idea_ of speech."[69]

The open mouth in Stricker's experiment not only prevents actual articulation of the labials, but our feeling of its openness keeps us from imagining their articulation, just as a sensation of glaring light will keep us from strongly imagining darkness. In persons whose auditory imagination is weak, the articulatory image seems to constitute the whole material for verbal thought. Professor Stricker says that in his own case no auditory image enters into the words of which he thinks.[70] Like most psychologists, however, he makes of his personal peculiarities a rule, and says that verbal thinking is normally and universally an exclusively motor representation. _I_ certainly get auditory images, both of vowels and of consonants, in addition to the articulatory images or feelings on which this author lays such stress. And I find that numbers of my students, after repeating his experiments, come to this conclusion. There is _at first_ a difficulty due to the open mouth. That, however, soon vanishes, as does also the difficulty of thinking of one vowel whilst continuously sounding another. What probably remains true, however, is that most men have a less auditory and a more articulatory verbal imagination than they are apt to be aware of. Professor Stricker himself has acoustic images, and can imagine the sounds of musical instruments, and the peculiar voice of a friend. A statistical inquiry on a large scale, into the variations of acoustic, tactile, and motor imagination, would probably bear less fruit than Galton's inquiry into visual images. A few monographs by competent observers, like Stricker, about their own peculiarities, would give much more valuable information about the diversities which prevail.[71]

_Touch-images_ are very strong in some people. The most vivid touch-images come when we ourselves barely escape local injury, or when we see another injured. The place may then actually tingle with the imaginary sensation--perhaps not altogether imaginary, since goose-flesh, paling or reddening, and other evidences of actual muscular contraction in the spot may result.

"An educated man," says a writer who must always be quoted when it
is question of the powers of imagination,[72] "told me once that on
entering his house one day he received a shock from crushing the
finger of one of his little children in the door. At the moment of his
fright he felt a violent pain in the corresponding finger of his own
body, and this pain abode with him three days."

The same author makes the following discrimination, which probably most men could verify:

"On the skin I easily succeed in bringing out suggested sensations
wherever I will. But because it is necessary to protract the mental
effort I can only awaken such sensations as are in their nature
prolonged, as warmth, cold, pressure. Fleeting sensations, as those
of a prick, a cut, a blow, etc., I am unable to call up, because I
cannot imagine them _ex abrupto_ with the requisite intensity. The
sensations of the former order I can excite upon any part of the skin;
and they may become so lively that, whether I will or not, I have to
pass my hand over the place just as if it were a real impression on
the skin."[73]

_Meyer's account of his own visual images_ is very interesting; and with it we may close our survey of differences between the normal powers of imagining in different individuals.

"With much practice," he says, "I have succeeded in making it possible
for me to call up subjective visual sensations at will. I tried all
my experiments by day or at night with closed eyes. At first it was
very difficult. In the first experiments which succeeded the whole
picture was luminous, the shadows being given in a somewhat less
strong bluish light. In later experiments I saw the objects dark, with
bright outlines, or rather I saw outline drawings of them, bright on
a dark ground. I can compare these drawings less to chalk drawings on
a blackboard than to drawings made with phosphorus on a dark wall at
night, though the phosphorus would show luminous vapors which were
absent from my lines. If I wished, for example, to see a face, without
intending that of a particular person, I saw the outline of a profile
against the dark background. When I tried to repeat an experiment
of the elder Darwin I saw only the edges of the die as bright lines
on a dark ground. Sometimes, however, I saw the die really white and
its edges black; it was then on a paler ground. I could soon at will
change between a white die with black borders on a light field, and
a black die with white borders on a dark field; and I can do this at
any moment now. After long practice ... these experiments succeeded
better still. I can now call before my eyes almost any object which
I please, as a subjective appearance, and this in its own natural
color and illumination. I see them almost always on a more or less
light or dark, mostly dimly changeable ground. Even known faces I can
see quite sharp, with the true color of hair and cheeks. It is odd
that I see these faces mostly in profile, whereas those described [in
the previous extract] were all full-face. Here are some of the final
results of these experiments:
"1) Some time after the pictures have arisen they vanish or change
into others, without my being able to prevent it.
"2) When the color does not integrally belong to the object, I cannot
always control it. A face, e.g., never seems to me blue, but always
in its natural color; a red cloth, on the other hand, I can sometimes
change to a blue one.
"3) I have sometimes succeeded in seeing pure colors without objects;
they then fill the entire field of view.
"4) I often fail to see objects which are not known to me, mere
fictions of my fancy, and instead of them there will appear familiar
objects of a similar sort; for instance, I once tried to see a brass
sword-hilt with a brass guard, instead of which the more familiar
picture of a rapier-guard appeared.
"5) Most of these subjective appearances, especially when they were
bright, left after-images behind them when the eyes were quickly
opened during their presence. For example, I thought of a silver
stirrup, and after I had looked at it a while I opened my eyes and for
a long while afterwards saw its after-image.
"These experiments succeeded best when I lay quietly on my back and
closed my eyes. I could bear no noise about me, as this kept the
vision from attaining the requisite intensity. The experiments succeed
with me now so easily that I am surprised they did not do so at
first, and I feel as though they ought to succeed with everyone. The
important point in them is to get the image sufficiently intense by
the exclusive direction of the attention upon it, and by the removal
of all disturbing impressions."[74]

_The negative after-images which succeeded upon Meyer's imagination when he opened his eyes_ are a highly interesting, though rare, phenomenon. So far as I know there is only one other published report of a similar experience.[75] It would seem that in such a case the neural process corresponding to the imagination must be the entire tract concerned in the actual sensation, even down as far as the retina. This leads to a new question to which we may now turn--of what is


THE NEURAL PROCESS WHICH UNDERLIES IMAGINATION?


The commonly-received idea is that it is only a milder degree of the same process which took place when the thing now imagined was sensibly perceived. Professor Bain writes:

"Since a sensation in the first instance diffuses nerve-currents
through the interior of the brain outwards to the organs of expression
and movement,--the persistence of that sensation, after the outward
exciting cause is withdrawn, can be but a continuance of the same
diffusive currents, perhaps less intense, but not otherwise different.
The shock remaining in the ear and brain, after the sound of thunder,
must pass through the same circles, and operate in the same way as
during the actual sound. We can have no reason for believing that,
in this self-sustaining condition, the impression changes its seat,
or passes into some new circles that have the special property of
retaining it. Every part actuated _after_ the shock must have been
actuated _by_ the shock, only more powerfully. With this single
difference of intensity, the mode of existence of a sensation existing
after the fact is essentially the same as its mode of existence during
the fact.... Now if this be the case with impressions _persisting_
when the cause has ceased, what view are we to adopt concerning
impressions _reproduced_ by mental causes alone, or without the aid
of the original, as in ordinary recollection? What is the manner of
occupation of the brain with a resuscitated feeling of resistance,
a smell or a sound? There is only one answer that seems admissable.
_The renewed feeling occupies the very same parts, and in the same
manner, as the original feeling, and no other parts, nor in any other
assignable manner._ I imagine that if our present knowledge of the
brain had been present to the earliest speculators, this is the only
hypothesis that would have occurred to them. For where should a past
feeling be embodied, if not in the same organs as the feeling when
present? It is only in this way that its identity can be preserved; a
feeling differently embodied would be a different feeling."[76]

It is not plain from Professor Bain's text whether by the 'same parts' he means only the same parts _inside the brain_, or the same _peripheral_ parts also, as those occupied by the original feeling. The examples which he himself proceeds to give are almost all cases of imagination of _movement_, in which the peripheral organs are indeed affected, for actual movements of a weak sort are found to accompany the idea. This is what we should expect. All currents tend to run forward in the brain and discharge into the muscular system; and the idea of a movement tends to do this with peculiar facility. But the question remains: Do currents run _backward_, so that if the optical centres (for example) are excited by 'association' and a visual object is imagined, a current runs _down to the retina_ also, and excites that sympathetically with the higher tracts? In other words, _can peripheral sense-organs be excited from above, or only from without? Are they excited in imagination?_ Professor Bain's instances are almost silent as to this point. All he says is this:

"We might think of a blow on the hand until the skin were actually
irritated and inflamed. The attention very much directed to any part
of the body, as the great toe, for instance, is apt to produce a
distinct feeling in the part, which we account for only by supposing a
revived nerve-current to flow there, making a sort of false sensation,
an influence from within mimicking the influences from without in
sensation proper.--(See the writings of Mr. Braid, of Manchester, on
Hypnotism, etc.)"

If I may judge from my own experience, all feelings of this sort are consecutive upon motor currents invading the skin and producing contraction of the muscles there, the muscles whose contraction gives 'goose-flesh' when it takes place on an extensive scale. I never get a _feeling_ in the skin, however strongly I _imagine_ it, until some actual change in the condition of the skin itself has occurred. The truth seems to be that the cases where peripheral sense-organs are directly excited in consequence of imagination are exceptional rarities, if they exist at all. _In common cases of imagination it would seem more natural to suppose that the seat of the process is purely cerebral, and that the sense-organ is left out._ Reasons for such a conclusion would be briefly these:

1) In imagination the _starting-point_ of the process must be in the brain. Now we know that currents usually flow one way in the nervous system; and for the peripheral sense-organs to be excited in these cases, the current would have to flow backward.

2) There is between imagined objects and felt objects a difference of conscious quality which may be called almost absolute. It is hardly possible to confound the liveliest image of fancy with the weakest real sensation. The felt object has a plastic reality and outwardness which the imagined object wholly lacks. Moreover, as Fechner says, in imagination the attention feels as if drawn backwards to the brain; in sensation (even of after-images) it is directed forward towards the sense-organ.[77] The difference between the two processes feels like one of kind, and not like a mere 'more' or 'less' of the same.[78] If a sensation of sound were only a strong imagination, and an imagination a weak sensation, there ought to be a border-line of experience where we never could tell whether we were hearing a weak sound or imagining a strong one. In comparing a present sensation felt with a past one imagined, it will be remembered that we often judge the imagined one to _have been the stronger_ (see above, Vol. I p. 500, note). This is inexplicable if the imagination be simply a weaker excitement of the sensational process.

To these reasons the following objections may be made:

To 1): The current demonstrably _does_ flow backward down the optic nerve in Meyer's and Féré's negative after-image. Therefore it _can_ flow backward; therefore it _may_ flow backward in some, however slight, degree, in all imagination.[79]

To 2): The difference alleged is not absolute, and sensation and imagination _are_ hard to discriminate where the sensation is so weak as to be just perceptible. At night hearing a very faint striking of the hour by a far-off clock, our imagination reproduces both rhythm and sound, and it is often difficult to tell which was the last real stroke. So of a baby crying in a distant part of the house, we are uncertain whether we still hear it, or only imagine the sound. Certain violin-players take advantage of this in diminuendo terminations. After the pianissimo has been reached they continue to bow as if still playing, but are careful not to touch the strings. The listener hears in imagination a degree of sound fainter still than the preceding pianissimo. This phenomenon is not confined to hearing:

"If we slowly approach our finger to a surface of water, we often
deceive ourselves about the moment in which the wetting occurs. The
apprehensive patient believes himself to feel the knife of the surgeon
whilst it is still at some distance."[80]

Visual perception supplies numberless instances in which the same sensation of vision is perceived as one object or another according to the interpretation of the mind. Many of these instances will come before us in the course of the next two chapters; and in Chapter XIX similar illusions will be described in the other senses. Taken together, all these facts would force us to admit that _the subjective difference between imagined and felt objects is less absolute than has been claimed, and that the cortical processes which underlie imagination and sensation are not quite as discrete as one at first is tempted to suppose. That peripheral sensory processes are ordinarily involved in imagination seems improbable; that they may sometimes be aroused from the cortex downwards cannot, however, be dogmatically denied._

      *       *       *       *       *

_The imagination-process_ CAN _then pass over into the sensation-process._ In other words, genuine sensations _can_ be centrally originated. When we come to study hallucinations in the chapter on Outer Perception, we shall see that this is by no means a thing of rare occurrence. At present, however, we must admit that _normally the two processes do_ NOT _pass over into each other_; and we must inquire why. One of two things must be the reason. Either

1. Sensation-processes occupy a different _locality_ from imagination-processes; or

2. Occupying the same locality, they have an _intensity_ which under normal circumstances currents from other cortical regions are incapable of arousing, and to produce which currents from the periphery are required.

_It seems almost certain_ (after what was said in Chapter II. pp. 49-51) _that the imagination-process differs from the sensation-process by its intensity rather than by its locality._ However it may be with lower animals, the assumption that ideational and sensorial centres are locally distinct appears to be supported by no facts drawn from the observation of human beings. After occipital destruction, the hemianopsia which results in man is sensorial blindness, not mere loss of optical ideas. Were there centres for crude optical sensation below the cortex, the patients in these cases would still feel light and darkness. Since they do not preserve even this impression on the lost half of the field, we must suppose that there are no centres for vision of any sort whatever below the cortex, and that the corpora quadrigemina and other lower optical ganglia are organs for reflex movement of eye-muscles and not for conscious sight. Moreover there are no facts which oblige us to think that, within the occipital cortex, one part is connected with sensation and another with mere ideation or imagination. The pathological cases assumed to prove this are all better explained by disturbances of conduction between the optical and other centres (see p. 50). In bad cases of hemianopsia the patient's images depart from him together with his sensibility to light. They depart so completely that he does not even know what is the matter with him. To perceive that one is blind to the right half of the field of view one must have an idea of that part of the field's possible existence. But the defect in these patients has to be revealed to them by the doctor, they themselves only knowing that there is 'something wrong' with their eyes. What you have no idea of you cannot miss; and their not definitely missing this great region out of their sight seems due to the fact that their very idea and memory of it is lost along with the sensation. A man blind of his eyes merely, sees _darkness_. A man blind of his visual brain-centres can no more see darkness out of the parts of his retina which are connected with the brain-lesion than he can see it out of the skin of his back. He cannot see at all in that part of the field; and he cannot think of the light which he ought to be feeling _there_, for the very notion of the existence of that particular 'there' is cut out of his mind.[81]

Now if we admit that sensation and imagination are due to the activity of the same centres in the cortex, we can see a very good teleological reason why they should correspond to discrete kinds of process in these centres, and why the process which gives the sense that the object is really there ought normally to be arousable only by currents entering from the periphery and not by currents from the neighboring cortical parts. We can see, in short, why _the sensational process_ OUGHT TO _be discontinuous with all normal ideational processes, however intense_. For, as Dr. Münsterberg justly observes:

"Were there not this peculiar arrangement we should not distinguish
reality and fantasy, our conduct would not be accommodated to the
facts about us, but would be inappropriate and senseless, and we could
not keep ourselves alive.... That our thoughts and memories should
be copies of sensations with their intensity greatly reduced is thus
a consequence deducible logically from the natural adaptation of the
cerebral mechanism to its environment."[82]

Mechanically the discontinuity between the ideational and the sensational kinds of process must mean that when the greatest ideational intensity has been reached, an order of _resistance_ presents itself which only a new order of force can break through. The current from the periphery is the new order of force required; and what happens after the resistance is overcome is the sensational process. We may suppose that the latter consists in some new and more violent sort of disintegration of the neural matter, which now explodes at a deeper level than at other times.

Now how shall we conceive of the 'resistance' which prevents this sort of disintegration from taking place, this sort of intensity in the process from being attained, so much of the time? It must be either an intrinsic resistance, some force of cohesion in the neural molecules themselves; or an extrinsic influence, due to other cortical cells. When we come to study the process of hallucination we shall see that both factors must be taken into account. There is a degree of inward molecular cohesion in our brain-cells which it probably takes a sudden inrush of destructive energy to spring apart. Incoming peripheral currents possess this energy from the outset. Currents from neighboring cortical regions might attain to it if they could _accumulate_ within the centre which we are supposed to be considering. But since during waking hours every centre communicates with others by association-paths, no such accumulation can take place. The cortical currents which run in run right out again, awakening the next ideas; the level of tension in the cells does not rise to the higher explosion-point; and the latter must be gained by a sudden current from the periphery or not at all.

      *       *       *       *       *

[49] Prof. Jastrow has ascertained by statistical inquiry among the blind that if their blindness have occurred before a period embraced between the fifth and seventh years the visual centres seem to decay, and visual dreams and images are gradually outgrown. If sight is lost after the seventh year, visual imagination seems to survive through life. See Prof. J.'s interesting article on the Dreams of the Blind, in the New Princeton Review for January 1888.

[50] Impression means sensation for Hume.

[51] Treatise on Human Nature, part i. § vii.

[52] Huxley's Hume, pp. 92-94.

[53] On Intelligence (N. Y.), vol. ii. p. 139.

[54] Principles, Introd. § 13. Compare also the passage quoted above, vol. I, p. 469.

[55] The differences noted by Fechner between after-images and images of imagination proper are as follows:

_After Images._ _Imagination-images._

Feel coercive; Feel subject to our spontaneity;

Seem unsubstantial, vaporous; Have, as it were, more body;

Are sharp in outline; Are blurred;

Are bright; Are darker than even the darkest

                                       black of the after-images;

Are almost colorless; Have lively coloration;

Are continuously enduring; Incessantly disappear, and have to

                                       be renewed by an effort of will.
                                       At last even this fails to revive
                                       them.

Cannot be voluntarily changed. Can be exchanged at will for

                                       others.

Are exact copies of originals. Cannot violate the necessary laws

                                       of appearance of their
                                       originals--e.g., a man cannot be
                                       imagined from in front and behind
                                       at once. The imagination must walk
                                       round him, so to speak;

Are more easily got with shut than Are more easily had with open than with open eyes; with shut eyes;

Seem to move when the head or eyes Need not follow movements of head move; or eyes.

The field within which they appear The field is extensive in three (with closed eyes) is dark, contracted, dimensions, and objects can be flat, close to the eyes, in imagined in it above or behind front, and the images have no almost as easily as in front. perspective;

The attention seems directed forwards In imagining, the attention feels towards the sense-organ, in as if drawn backwards towards the observing after-images. brain.


Finally, Fechner speaks of the impossibility of attending to both after-images and imagination-images at once, even when they are of the same object and might be expected to combine. All these differences are true of Fechner; but many of them would be untrue of other persons. I quote them as a type of observation which any reader with sufficient patience may repeat. To them may be added, as a universal proposition, that after-images seem larger if we project them on a distant screen, and smaller if we project them on a near one, whilst no such change takes place in mental pictures.

[56] [I am myself a good draughtsman, and have a very lively interest in pictures, statues, architecture and decoration, and a keen sensibility to artistic effects. But I am an extremely poor visualizer, and find myself often unable to reproduce in my mind's eye pictures which I have most carefully examined.--W. J.]

[57] See also McCosh and Osborne, Princeton Review, Jan. 1884. There are some good examples of high development of the Faculty in the London Spectator, Dec. 28, 1878, pp. 1631, 1634, Jan. 4, 11, 25, and March 18, 1879.

[58] Take the following report from one of my students: "I am unable to form in my mind's eye any visual likeness of the table whatever. After many trials, I can only get a hazy surface, with nothing on it or about it. I can see no variety in color, and no positive limitations in extent, while I cannot see what I see well enough to determine its position in respect to my eye, or to endow it with any quality of size. I am in the same position as to the word _dog_. I cannot see it in my mind's eye at all; and so cannot tell whether I should have to run my eye along it, if I did see it."

[59] Progrès Médical, 21 juillet. I abridge from the German report of the case in Wilbrand: Die Seelenblindheit (188).

[60] In a letter to Charcot this interesting patient adds that his character also is changed: "I was formerly receptive, easily made enthusiastic, and possessed a rich fancy. Now I am quiet and cold, and fancy never carries my thoughts away.... I am much less susceptible than formerly to anger or sorrow. I lately lost my dearly-beloved mother; but felt far less grief at the bereavement than if I had been able to see in my mind's eye her physiognomy and the phases of her suffering, and especially less than if I had been able to witness in imagination the outward effects of her untimely loss upon the members of the family."

[61] Psychologie du Raisonnement (1886), p. 25.

[62] [I am myself a very poor visualizer, and find that I can seldom call to mind even a single letter of the alphabet in purely retinal terms. I must trace the letter by running my mental eye over its contour in order that the image of it shall have any distinctness at all. On questioning a large number of other people, mostly students, I find that perhaps half of them say they have no such difficulty in seeing letters mentally. Many affirm that they can see an entire word at once, especially a short one like 'dog,' with no such feeling of creating the letters successively by tracing them with the eye.--W. J.]

[63] It is hardly needful to say that in modern primary education, in which the blackboard is so much used, the children are taught their letters, etc., by all possible channels at once, sight, hearing, and movement.

[64] See an interesting case of a similar sort, reported by Farges, in l'Encéphale, 7me Année, p. 545.

[65] Philosophical Transactions, 1841, p. 65.

[66] Studien über die Sprachvorstellungen (1880), and Studien über die Bewegungsvorstellungen (1882).

[67] Prof. Stricker admits that by practice he has succeeded in making his eye-movements 'act vicariously' for his leg-movements in imagining men walking.

[68] Bewegungsvorstellungen, p. 6.

[69] Bain: Senses and Intellect, p. 339.

[70] Studien über Sprachvorstellungen, 28, 31, etc. Cf. pp. 49-50, etc. Against Stricker, see Stumpf, Tonpsychol., 155-162, and Revue Philosophique, xx. 617. See also Paulhan, Rev. Philosophique, xvi. 405. Stricker replies to Paulhan in vol. xviii. p. 685. P. retorts in vol. xix p. 118. Stricker reports that out of 100 persons questioned he found only _one_ who had _no_ feeling in his lips when silently thinking the letters M, B, P; and out of 60 only _two_ who were conscious of no internal articulation whilst reading (pp. 59-60).

[71] I think it must be admitted that some people have no vivid substantive images in _any_ department of their sensibility. One of my students, an intelligent youth, denied so pertinaciously that there was _anything_ in his mind _at all_ when he thought, that I was much perplexed by his case. I myself certainly have no such vivid play of nascent movements or motor images as Professor Stricker describes. When I seek to represent a row of soldiers marching, all I catch is a view of stationary legs first in one phase of movement and then in another, and these views are extremely imperfect and momentary. Occasionally (especially when I try to stimulate my imagination, as by repeating Victor Hugo's lines about the regiment,

   "Leur pas est si correct, sans tarder ni courir,
   Qu'on croit voir des ciseaux se fermer et s'ouvrir,")

I seem to get an instantaneous glimpse of an actual movement, but it is to the last degree dim and uncertain. All these images seem at first as if purely retinal. I think, however, that rapid eye-movements accompany them, though these latter give rise to such slight feelings that they are almost impossible of detection. Absolutely no leg-movements of my own are there; in fact, to call such up arrests my imagination of the soldiers. My optical images are in general very dim, dark, fugitive, and contracted. It would be utterly impossible to _draw_ from them, and yet I perfectly well distinguish one from the other. My auditory images are excessively inadequate reproductions of their originals. I have _no_ images of taste or smell. Touch-imagination is fairly distinct, but comes very little into play with most objects thought of. Neither is all my thought verbalized; for I have shadowy schemes of relation, as apt to terminate in a nod of the head or an expulsion of the breath as in a definite word. On the whole, vague images or sensations of movement inside of my head towards the various parts of space in which the terms I am thinking of either lie or are momentarily symbolized to lie together with movements of the breath through my pharynx and nostrils, form a by no means inconsiderable part of my _thought-stuff_. I doubt whether my difficulty in giving a clearer account is wholly a matter of inferior power of introspective attention, though that doubtless plays its part. Attention, _ceteris paribus_, must always be inferior in proportion to the feebleness of the internal images which are offered it to hold on to.

[72] Geo. Herm. Meyer, Untersuchungen üb. d. Physiol. d. Nervenfaser (1843), p. 233. For other cases see Tuke's Influence of Mind upon Body, chaps. ii. and vii.

[73] Meyer, _op. cit._ p. 238.

[74] Meyer, _op. cit._ pp. 238-41.

[75] That of Dr. Ch. Féré in the Revue Philosophique, xx. 364. Johannes Müller's account of hypnagogic hallucinations floating before the eyes for a few moments after these had been opened, seems to belong more to the category of spontaneous hallucinations (see his Physiology, London, 1843, p. 1394). It is impossible to tell whether the words in Wundt's Vorlesungen, i. 387, refer to a personal experience of his own or not; probably not. _Il va sans dire_ that an inferior visualizer like myself can get no such after-images. Nor have I as yet succeeded in getting report of any from my students.

[76] Senses and Intellect, p. 338.

[77] See above, note 55.

[78] V. Kandinsky (Kritische u. klinische Betrachtungen im Gebiete der Sinnestäuschungen (Berlin, 1885), p. 135 ff.) insists that in even the liveliest pseudo-hallucinations (see below, Chapter XX), which may be regarded as the intensest possible results of the imaginative process, there is no outward objectivity perceived in the thing represented, and that a _ganzer Abgrund_ separates these 'ideas' from true hallucination and objective perception.

[79] It seems to also flow backwards in certain hypnotic hallucinations. Suggest to a 'Subject' in the hypnotic trance that a sheet of paper has a red cross upon it, then pretend to remove the imaginary cross, whilst you tell the Subject to look fixedly at a dot upon the paper, and he will presently tell you that he sees a 'bluish-green' cross. The genuineness of the result has been doubted, but there seems no good reason for rejecting M. Binet's account (Le Magnetisme Animal, 1887, p. 188). M. Binet, following M. Parinaud, and on the faith of a certain experiment, at one time believed, the optical brain-centres and not the retina to be the seat of ordinary negative after-images. The experiment is this: Look fixedly, with one eye open, at a colored spot on a white background. Then close that eye and look fixedly with the _other_ eye at a plain surface. A negative after-image of the colored spot will presently appear. (Psychologie du Raisonnement, 1886, p. 45.) But Mr. Delabarre has proved (American Journal of Psychology, ii. 326) that this after-image is due, not to a higher cerebral process, but to the fact that the retinal process in the _closed_ eye affects consciousness at certain moments, and that its object is then projected into the field seen by the eye which is open. M. Binet informs me that he is converted by the proofs given by Mr. Delabarre.

The fact remains, however, that the negative after-images of Herr Meyer, M. Féré, and the hypnotic subjects, form an exception to all that we know of nerve-currents, if they are due to a refluent centrifugal current to the retina. It may be that they will hereafter be explained in some other way. Meanwhile we can only write them down as a paradox. Sig. Sergi's theory that there is _always_ a refluent wave in perception hardly merits serious consideration (Psychologie Physiologique, pp. 99, 189). Sergi's theory has recently been reaffirmed with almost incredible crudity by Lombroso and Ottolenghi in the Revue Philosophique, xxix. 70 (Jan. 1890).

[80] Lotze, Med. Psych. p. 509.

[81] See an important article by Binet in the Revue Philosophique, xxvi. 481 (1888); also Dufour, in Revue Méd. de la Suisse Romande, 1889. No. 8, cited in the Neurologisches Centralblatt, 1890. p. 48.

[82] Die Willenshandlung (1888), pp. 129-40.



CHAPTER XIX.

THE PERCEPTION OF 'THINGS.'

PERCEPTION AND SENSATION COMPARED.


A pure sensation we saw above, p. 7, to be an abstraction never realized in adult life. Any quality of a thing which affects our sense-organs does also more than that: it arouses processes in the hemispheres which are due to the organization of that organ by past experiences, and the result of which in consciousness are commonly described as ideas which the sensation suggests. The first of these ideas is that of the _thing_ to which the sensible quality belongs. _The consciousness of particular material things present to sense_ is nowadays called _perception_.[83] The consciousness of such things may be more or less complete; it may be of the mere name of the thing and its other essential attributes, or it may be of the thing's various remoter relations. It is impossible to draw any sharp line of distinction between the barer and the richer consciousness, because the moment we get beyond the first crude sensation all our consciousness is a matter of suggestion, and the various suggestions shade gradually into each other, being one and all products of the same psychological machinery of association. In the directer consciousness fewer, in the remoter more, associative processes are brought into play.

_Perception thus differs from sensation by the consciousness of farther facts associated with the object of the sensation:_

"When I lift my eyes from the paper on which I am writing I see the
chairs and tables and walls of my room, each of its proper shape and
at its proper distance. I see, from my window, trees and meadows, and
horses and oxen, and distant hills. I see each of its proper size, of
its proper form, and at its proper distance; and these particulars
appear as immediate informations of the eye, as the colors which I
see by means of it. Yet philosophy has ascertained that we derive
nothing from the eye whatever but sensations of color.... How, then,
is it that we receive accurate information, by the eye, of size and
shape and distance? By association merely. The colors upon a body
are different, according to its figure, its shape, and its size. But
the sensations of color and what we may here, for brevity, call the
sensations of extension, of figure, of distance, have been so often
united, felt in conjunction, that the sensation of the color is never
experienced without raising the ideas of the extension, the figure,
the distance, in such intimate union with it, that they not only
cannot be separated, but are actually supposed to be seen. The sight,
as it is called, of figure, or distance, appearing as it does a simple
sensation, is in reality a complex state of consciousness--a sequence
in which the antecedent, a sensation of color, and the consequent,
a number of ideas, are so closely combined by association that they
appear not one idea, but one sensation."

This passage from James Mill[84] gives a clear statement of the doctrine which Berkeley in his Theory of Vision made for the first time an integral part of Psychology. Berkeley compared our visual sensations to the words of a language, which are but signs or occasions for our intellects to pass to what the speaker means. As the sounds called words have no inward affinity with the ideas they signify, so neither have our visual sensations, according to Berkeley, any inward affinity with the things of whose presence they make us aware. Those things are _tangibles;_ their real properties, such as shape, size, mass, consistency, position, reveal themselves only to touch. But the visible signs and the tangible significates are by long custom so "closely twisted, blended, and incorporated together, and the prejudice is so confirmed and riveted in our thoughts by a long tract of time, by the use of language, and want of reflection,"[85] that we think we _see_ the whole object, tangible and visible alike, in one simple indivisible act.

_Sensational and reproductive brain-processes combined, then, are what give us the content of our perceptions._ Every concrete particular material thing is a conflux of sensible qualities, with which we have become acquainted at various times. Some of these qualities, since they are more constant, interesting, or practically important, we regard as essential constituents of the thing. In a general way, such are the tangible shape, size, mass, etc. Other properties, being more fluctuating, we regard as more or less accidental or inessential. We call the former qualities the reality, the latter its appearances. Thus, I hear a sound, and say 'a horse-car'; but the sound is not the horse-car, it is one of the horse-car's least important manifestations. The real horse-car is a feelable, or at most a feelable and visible, thing which in my imagination the sound calls up. So when I get, as now, a brown eye-picture with lines not parallel, and with angles unlike, and call it my big solid rectangular walnut library-table, that picture is not the table. It is not even like the table as the table is for vision, when rightly seen. It is a distorted perspective view of three of the sides of what I mentally _perceive_ (more or less) in its totality and undistorted shape. The back of the table, its square corners, its size, its heaviness, are features of which I am conscious when I look, almost as I am conscious of its name. The suggestion of the name is of course due to mere custom. But no less is that of the back, the size, weight, squareness, etc.

Nature, as Reid says, is frugal in her operations, and will not be at the expense of a particular instinct to give us that knowledge which experience and habit will soon produce. Reproduced sights and contacts tied together with the present sensation in the unity of a _thing_ with a name, these are the complex objective stuff out of which my actually perceived table is made. Infants must go through a long education of the eye and ear before they can perceive the realities which adults perceive. _Every perception is an acquired perception._[86]

_Perception may then be defined_, in Mr. Sully's words, as that process by which the mind

"supplements a sense-impression by an accompaniment or escort of
revived sensations, the whole aggregate of actual and revived
sensations being solidified or 'integrated' into the form of a
percept, that is, an apparently immediate apprehension or cognition of
an object now present in a particular locality or region of space."[87]

Every reader's mind will supply abundant examples of the process here described; and to write them down would be therefore both unnecessary and tedious. In the chapter on Space we have already discussed some of the more interesting ones; for in our perceptions of shape and position it is really difficult to decide how much of our sense of the object is due to reproductions of past experience, and how much to the immediate sensations of the eye. I shall accordingly confine myself in the rest of this chapter to certain additional generalities connected with the perceptive process.

      *       *       *       *       *

The first point is relative to that 'solidification' or 'integration,' whereof Mr. Sully speaks, of the present with the absent and merely represented sensations. Cerebrally taken, these words mean no more than this, that the process aroused in the sense-organ has shot into various paths which habit has already organized in the hemispheres, and that instead of our having the sort of consciousness which would be correlated with the simple sensorial process, we have that which is correlated with this more complex process. This, as it turns out, is the consciousness of that more complex 'object,' the whole 'thing,' instead of being the consciousness of that more simple object, the few qualities or attributes which actually impress our peripheral nerves. This consciousness must have the unity which every 'section' of our stream of thought retains so long as its objective content does not sensibly change. More than this we cannot say; we certainly ought not to say what usually is said by psychologists, and treat the perception as a sum of distinct psychic entities, the present sensation namely, _plus_ a lot of images from the past, all 'integrated' together in a way impossible to describe. The perception is one state of mind or nothing--as I have already so often said.

In many cases it is easy to compare the psychic results of the sensational with those of the perceptive process. We then see a marked difference in the way in which the impressed portions of the object are felt, in consequence of being cognized along with the reproduced portion, in the higher state of mind. Their sensible quality changes under our very eye. Take the already-quoted catch, _Pas de lieu Rhône que nous_: one may read this over and over again without recognizing the sounds to be identical with those of the words _paddle your own canoe_. As we seize the English meaning the sound itself appears to change. Verbal sounds are usually perceived with their meaning at the moment of being heard. Sometimes, however, the associative irradiations are inhibited for a few moments (the mind being preoccupied with other thoughts) whilst the words linger on the ear as mere echoes of acoustic sensation. Then, usually, their interpretation suddenly occurs. But at that moment one may often surprise a change in the very _feel_ of the word. Our own language would sound very different to us if we heard it without understanding, as we hear a foreign tongue. Rises and falls of voice, odd sibilants and other consonants, would fall on our ear in a way of which we can now form no notion. Frenchmen say that English sounds to them like the _gazouillement des oiseaux_--an impression which it certainly makes on no native ear. Many of us English would describe the sound of Russian in similar terms. All of us are conscious of the strong inflections of voice and explosives and gutturals of German speech in a way in which no German can be conscious of them.

This is probably the reason why, if we look at an isolated printed word and repeat it long enough, it ends by assuming an entirely unnatural aspect. Let the reader try this with any word on this page. He will soon begin to wonder if it can possibly be the word he has been using all his life with that meaning. It stares at him from the paper like a glass eye, with no speculation in it. Its body is indeed there, but its soul is fled. It is reduced, by this new way of attending to it, to its sensational nudity. We never before attended to it in this way, but habitually got it clad with its meaning the moment we caught sight of it, and rapidly passed from it to the other words of the phrase. We apprehended it, in short, with a cloud of associates, and thus perceiving it, we felt it quite otherwise than as we feel it now divested and alone.

Another well-known change is when we look at a landscape with our head upside down. Perception is to a certain extent baffled by this manœuvre; gradations of distance and other space-determinations are made uncertain; the reproductive or associative processes, in short, decline; and, simultaneously with their diminution, the colors grow richer and more varied, and the contrasts of light and shade more marked. The same thing occurs when we turn a painting bottom upward. We lose much of its meaning, but, to compensate for the loss, we feel more freshly the value of the mere tints and shadings, and become aware of any lack of purely sensible harmony or balance which they may show.[88] Just so, if we lie on the floor and look up at the mouth of a person talking behind us. His lower lip here takes the habitual place of the upper one upon our retina, and seems animated by the most extraordinary and unnatural mobility, a mobility which now strikes us because (the associative processes being disturbed by the unaccustomed point of view) we get it as a naked sensation and not as part of a familiar object perceived.

On a later page other instances will meet us. For the present these are enough to prove our point. Once more we find ourselves driven to admit that when qualities of an object impress our sense and we thereupon perceive the object, the sensation as such of those qualities does not still exist inside of the perception and form a constituent thereof. The sensation is one thing and the perception another, and neither can take place at the same time with the other, because their cerebral conditions are not the same. They may _resemble_ each other, but in no respect are they identical states of mind.


PERCEPTION IS OF DEFINITE AND PROBABLE THINGS.


The chief cerebral conditions of perception are the paths of association irradiating from the sense-impression, which may have been already formed. If a certain sensation be strongly associated with the attributes of a certain thing, that thing is almost sure to be perceived when we get the sensation. Examples of such things would be familiar people, places, etc., which we recognize and name at a glance. But _where the sensation is associated with more than one reality_, so that either of two discrepant sets of residual properties may arise, the perception is doubtful and vacillating, and _the most that can then be said of it is that it will be of a_ PROBABLE _thing_, of the thing which would most usually have given us that sensation.

In these ambiguous cases it is interesting to note that perception is rarely abortive; _some_ perception takes place. The two discrepant sets of associates do not neutralize each other or mix and make a blur. What we more commonly get is first one object in its completeness, and then the other in its completeness. In other words, _all brain-processes are such as give rise to what we may call_ FIGURED _consciousness_. If paths are irradiated at all, they are irradiated in consistent systems, and occasion thoughts of definite objects, not mere hodge-podges of elements. Even where the brain's functions are half thrown out of gear, as in aphasia or dropping asleep, this law of figured consciousness holds good. A person who suddenly gets sleepy whilst reading aloud will read wrong; but instead of emitting a mere broth of syllables, he will make such mistakes as to read 'supper-time' instead of 'sovereign,' 'overthrow' instead of 'opposite,' or indeed utter entirely imaginary phrases, composed of several definite words, instead of phrases of the book. So in aphasia: where the disease is mild the patient's mistakes consist in using entire wrong words instead of right ones. Only in the gravest lesions does he become quite inarticulate. These facts show how subtle is the associative link; how delicate yet how strong that connection among brain-paths which makes any number of them, once excited together, thereafter tend to vibrate as a systematic whole. A small group of elements, '_this_,' common to two systems, A and B, may touch off A or B according as accident decides the next step (see Fig. 47). If it happen that a single point leading from '_this_' to B is momentarily a little more pervious than any leading from '_this_' to A, then that little advantage will upset the equilibrium in favor of the entire system B. The currents will sweep first through that point and thence into all the paths of B, each increment of advance making A more and more impossible. The thoughts correlated with A and B, in such a case, will have objects different, though similar. The similarity will, however, consist in some very limited feature if the 'this' be small.

[Illustration: FIG. 47.]

_Thus the faintest sensations will give rise to the perception of definite things if only they resemble those which the things are wont to arouse._ In fact, a sensation must be strong and distinct in order not to suggest an object and, if it is a nondescript feeling, really to seem one. The auræ of epilepsy, globes of light, fiery vision, roarings in the ears, the sensations which electric currents give rise to when passed through the head, these are unfigured because they are strong. Weaker feelings of the same sort would probably suggest objects. Many years ago, after reading Maury's book, _Le Sommeil et les Rêves_, I began for the first time to observe those ideas which faintly flit through the mind at all times, words, visions, etc., disconnected with the main stream of thought, but discernible to an attention on the watch for them. A horse's head, a coil of rope, an anchor, are, for example, ideas which have come to me unsolicited whilst I have been writing these latter lines. They can often be explained by subtle links of association, often not at all. But I have not a few times been surprised, after noting some such idea, to find, on shutting my eyes, an after-image left on the retina by some bright or dark object recently looked at, and which had evidently suggested the idea. 'Evidently,' I say, because the general shape, size, and position of object thought-of and of after-image were the same, although the idea had details which the retinal image lacked. We shall probably never know just what part retinal after-images play in determining the train of our thoughts. Judging by my own experiences I should suspect it of being not insignificant.[89]


ILLUSIONS.


Let us now, for brevity's sake, treat A and B in Fig. 47 as if they stood for objects instead of brain-processes. And let us furthermore suppose that A and B are, both of them, objects which might probably excite the sensation which I have called '_this_,' but that on the present occasion A and not B is the one which actually does so. If, then, on this occasion '_this_' suggests A and not B, the result is a _correct perception_. But if, on the contrary, 'this' suggests B and not A, the result is a _false perception_, or, as it is technically called, an _illusion_. But the _process_ is the same, whether the perception be true or false.

Note that in every illusion what is false is what is inferred, not what is immediately given. The 'this,' if it were felt by itself alone, would be all right, it only becomes misleading by what it suggests. If it is a sensation of sight, it may suggest a tactile object, for example, which later tactile experiences prove to be not there. _The so-called 'fallacy of the senses,' of which the ancient sceptics made so much account, is not fallacy of the senses proper, but rather of the intellect, which interprets wrongly what the senses give._[90]

      *       *       *       *       *

So much premised, let us look a little closer at these illusions. They are due to two main causes. _The wrong object is perceived either because_

1) _Although not on this occasion the real cause, it is yet the habitual, inveterate, or most probable cause of 'this;'_ or because

2) _The mind is temporarily full of the thought of that object, and therefore 'this' is peculiarly prone to suggest it at this moment._

I will give briefly a number of examples under each head. The first head is the more important, because it includes a number of constant illusions to which all men are subject, and which can only be dispelled by much experience.


_Illusions of the First Type._


[Illustration: FIG. 48.]

One of the oldest instances dates from Aristotle. Cross two fingers and roll a pea, pen-holder, or other small object between them. It will seem double. Professor Croom Robertson has given the clearest analysis of this illusion. He observes that if the object be brought into contact first with the forefinger and next with the second finger, the two contacts seem to come in at different points of space. The forefinger-touch seems higher, though the finger is really lower; the second-finger-touch seems lower, though the finger is really higher. "We perceive the contacts as double because we refer them to two distinct parts of space." The touched sides of the two fingers are normally not together in space, and customarily never do touch one thing; the one thing which now touches them, therefore, seems in two places, i.e. seems two things.[91]

There is a whole batch of illusions which come from optical sensations interpreted by us in accordance with our usual rule, although they are now produced by an unusual object. The _stereoscope_ is an example. The eyes see a picture apiece, and the two pictures are a little disparate, the one seen by the right eye being a view of the object taken from a point slightly to the right of that from which the left eye's picture is taken. Pictures thrown on the two eyes by solid objects present this identical disparity. Whence we react on the sensation in our usual way, and perceive a solid. If the pictures be exchanged we perceive a hollow mould of the object, for a hollow mould would cast just such disparate pictures as these. Wheatstone's instrument, the _pseudoscope_, allows us to look at solid objects and see with each eye the other eye's picture. We then perceive the solid object hollow, _if it be an object which might probably be hollow,_ but not otherwise. A human face, e.g., never appears hollow to the pseudoscope. In this irregularity of reaction on different objects, some seem hollow, others not; the perceptive process is true to its law, which is _always to react on the sensation in a determinate and figured fashion if possible, and in as probable a fashion as the case admits_. To couple faces and hollowness violates all our habits of association. For the same reason it is very easy to make an intaglio cast of a face, or the painted inside of a pasteboard mask, look convex, instead of concave as they are.

Our sense of the _position_ of things with respect to our eye consists in suggestions of how we must move our hand to touch them. Certain places of the image on the retina, certain actively-produced positions of the eyeballs, are normally linked with the sense of every determinate position which an outer thing may come to occupy. Hence we perceive the usual position, even if the optical sensation be artificially brought from a different part of space. Prisms warp the light-rays in this way, and throw upon the retina the image of an object situated, say, at spot _a_ of space in the same manner in which (without the prisms) an object situated at spot _b_ would cast its image. Accordingly we feel for the object at _b_ instead of _a_. If the prism be before one eye only we see the object at _b_ with that eye, and in its right position _a_ with the other--in other words, we see it double. If both eyes be armed with prisms with their angle towards the right, we pass our hand to the right of all objects when we try rapidly to touch them. And this illusory sense of their position lasts until a new association is fixed, when on removing the prisms a contrary illusion at first occurs. Passive or unintentional changes in the position of the eyeballs seem to be no more kept account of by the mind than prisms are; so we spontaneously make no allowance for them in our perception of distance and movements. Press one of the eyeballs into a strained position with the finger, and objects move and are translocated accordingly, just as when prisms are used.

Curious _illusions of movement_ in objects occur whenever the eyeballs move without our intending it. We shall learn in the following chapter that the original visual feeling of movement is produced by any image passing over the retina. Originally, however, this sensation is definitely referred neither to the object nor to the eyes. Such definite reference grows up later, and obeys certain simple laws. We believe objects to move: 1) whenever we get the retinal movement-feeling, but think our eyes are still; and 2) whenever we think that our eyes move, but fail to get the retinal movement-feeling. We believe objects to be still, on the contrary, 1) whenever we get the retinal movement-feeling, but think our eyes are moving; and 2) whenever we neither think our eyes are moving, nor get the retinal movement-feeling. Thus the perception of the object's state of motion or rest depends on the notion we frame of our own eye's movement. Now many sorts of stimulation make our eyes move without our knowing it. If we look at a waterfall, river, railroad train, or any body which continuously passes in front of us in the same direction, it carries our eyes with it. This movement can be noticed in our eyes by a bystander. If the object keep passing towards our left, our eyes keep following whatever moving bit of it may have caught their attention at first, until that bit disappears from view. Then they jerk back to the right again, and catch a new bit, which again they follow to the left, and so on indefinitely. This gives them an oscillating demeanor, slow involuntary rotations leftward alternating with rapid voluntary jerks rightward. But _the oscillations continue_ for a while after the object has come to a standstill, or the eyes are carried to a new object, and this produces the illusion that things now move in the opposite direction. For we are unaware of the slow leftward automatic movements of our eyeballs, and think that the retinal movement-sensations thereby aroused must be due to a rightward motion of the object seen; whilst the rapid voluntary rightward movements of our eyeballs we interpret as attempts to pursue and catch again those parts of the object which have been slipping away to the left.

Exactly similar oscillations of the eyeballs are produced in _giddiness_, with exactly similar results. Giddiness is easiest produced by whirling on our heels. It is a feeling of the movement of our own head and body through space, and is now pretty well understood to be due to the irritation of the semi-circular canals of the inner ear.[92] When, after whirling, we stop, we seem to be spinning in the reverse direction for a few seconds, and then objects appear to continue whirling in the same direction in which, a moment previous, our body actually whirled. The reason is that our _eyes normally tend to maintain_ their field of view. If we suddenly turn our head leftwards it is hard to make the eyes follow. They roll in their orbits rightwards, by a sort of compensating inertia. Even though we _falsely think_ our head to be moving leftwards, this consequence occurs, and our eyes move rightwards--as may be observed in any one with vertigo after whirling. As these movements are unconscious, the retinal movement-feelings which they occasion are naturally referred to the objects seen. And the intermittent voluntary twitches of the eyes towards the left, by which we ever and anon recover them from the extreme rightward positions to which the reflex movement brings them, simply confirm and intensify our impression of a leftward-whirling field of view: we seem to ourselves to be periodically pursuing and overtaking the objects in their leftward flight. The whole phenomenon fades out after a few seconds. And it often ceases if we voluntarily fix our eyes upon a given point.[93]

_Optical vertigo,_ as these illusions of objective movement are called, results sometimes from brain-trouble, intoxications, paralysis, etc. A man will awaken with a weakness of one of his eye-muscles. An intended orbital rotation will then not produce its expected result in the way of retinal movement-feeling--whence false perceptions, of which one of the most interesting cases will fall to be discussed in later chapters.

      *       *       *       *       *

There is an illusion of movement of the opposite sort, with which every one is familiar at _railway stations_. Habitually, when we ourselves move forward, our entire field of view glides backward over our retina. When our movement is due to that of the windowed carriage, car, or boat in which we sit, all stationary objects visible through the window give us a sensation of gliding in the opposite direction. Hence, whenever we get this sensation, of a window with _all_ objects visible through it moving in one direction, we react upon it in our customary way, and perceive a stationary field of view, over which the window, and we ourselves inside of it, are passing by a motion of our own. Consequently when another train comes alongside of ours in a station, and fills the entire window, and, after standing still awhile, begins to glide away, we judge that it is _our_ train which is moving, and that the other train is still. If, however, we catch a glimpse of any part of the station through the windows, or between the cars, of the other train, the illusion of our own movement instantly disappears, and we perceive the other train to be the one in motion. This, again, is but making the usual and probable inference from our sensation.[94]

_Another illusion due to movement_ is explained by Helmholtz. Most wayside objects, houses, trees, etc., look small when seen out of the windows of a swift train. This is because we perceive them in the first instance unduly near. And we perceive them unduly near because of their extraordinarily rapid parallactic flight backwards. When we ourselves move forward all objects glide backwards, as aforesaid; but the nearer they are, the more rapid is this apparent translocation. Relative rapidity of passage backwards is thus so familiarly associated with nearness that when we feel it we perceive nearness. But with a given size of retinal image the nearer an object is, the smaller do we judge its actual size to be. Hence in the train, the faster we go, the nearer do the trees and houses seem, and the nearer they seem, the smaller do they look.[95]

      *       *       *       *       *

_Other illusions are due to the feeling of convergence_ being wrongly interpreted. When we converge our eyeballs we perceive an _approximation_ of whatever thing we may be looking at. Whatever things do approach whilst we look at them oblige us, so long as they are not very distant, to converge our eyes. Hence approach of the thing is the _probable_ objective fact when we feel our eyes converging. Now in most persons the internal recti muscles, to which convergence is due, are weaker than the others; and the entirely passive position of the eyeballs, the position which they assume when covered and looking at nothing in particular, is either that of parallelism or of slight divergence. Make a person look with both eyes at some near object, and then screen the object from _one_ of his eyes by a card or book. The chances are that you will see the eye thus screened turn just a little outwards. Remove the screen, and you will now see it turn in as it catches sight of the object again. The other eye meanwhile keeps as it was at first. To most persons, accordingly, all objects seem to _come nearer_ when, after looking at them with one eye, both eyes are used; and they seem to _recede_ during the opposite change. With persons whose external recti muscles are insufficient, the illusions may be of the contrary kind.

      *       *       *       *       *

_The size of the retinal image_ is a fruitful source of illusions. Normally, the retinal image grows larger as the object draws near. But the sensation yielded by this enlargement is also given by any object which really grows in size without changing its distance. Enlargement of retinal image is therefore an ambiguous sign. An opera-glass enlarges the moon. But most persons will tell you that she looks smaller through it, only a great deal nearer and brighter. They read the enlargement as a sign of approach; and the perception of approach makes them actually reverse the sensation which suggests it--by an exaggeration of our habitual custom of making allowance of the apparent enlargement of whatever object approaches us, and reducing it in imagination to its natural size. Similarly, in the theatre the glass brings the stage near, but hardly seems to magnify the people on it.

The well-known increased _apparent size of the moon on the horizon_ is a result of association and probability. It is seen through vaporous air, and looks dimmer and duskier than when it rides on high; and it is seen over fields, trees, hedges, streams, and the like, which break up the intervening space and make us the better realize the latter's extent. Both these causes make the moon seem more distant from us when it is low; and as its visual angle grows no less, we deem that it must be a larger body, and we so perceive it. It looks particularly enormous when it comes up directly behind some well-known large object, as a house or tree, distant enough to subtend an angle no larger than that of the moon itself.[96]

      *       *       *       *       *

_The feeling of accommodation_ also gives rise to false perceptions of size. Usually we accommodate our eyes for an object as it approaches us. Usually under these circumstances the object throws a larger retinal image. But believing the object to remain the same, we make allowance for this and treat the entire eye-feeling which we receive as significant of nothing but _approach_. When we relax our accommodation and at the same time the retinal image grows smaller, the probable cause is always a _receding_ object. The moment we put on convex glasses, however, the accommodation relaxes, but the retinal image grows larger instead of less. This is what would happen if our object, whilst receding, grew. Such a probable object we accordingly perceive, though with a certain vacillation as to the recession, for the growth in apparent size is also a probable sign of approach, and is at moments interpreted accordingly.--Atropin paralyzes the muscles of accommodation. It is possible to get a dose which will weaken these muscles without laming them altogether. When a known near object is then looked at we have to make the same voluntary strain to accommodate, as if it were a great deal nearer; but as its retinal image is not enlarged in proportion to this suggested approach, we deem that it must have grown smaller than usual. In consequence of this so-called _micropsy_, Aubert relates that he saw a man apparently no larger than a photograph. But the small size again made the man seem farther off. The real distance was two or three feet, and he seemed against the wall of the room.[97] Of these vacillations we shall have to speak again in the ensuing chapter.[98]

      *       *       *       *       *

[Illustration: FIG. 49.]

Mrs. C. L. Franklin has recently described and explained with rare acuteness an illusion of which the most curious thing is that it was never noticed before. Take a single pair of crossed lines (Fig. 49), hold them in a horizontal plane before the eyes, and look along them, at such a distance that with the right eye shut, 1, and with the left eye shut, 2, looks like the projection of a vertical line. Look steadily now at the point of intersection of the lines with both eyes open, and you will see a third line sticking up like a pin through the paper at right angles to the plane of the two first lines. The explanation of this illusion is very simple, but so circumstantial that I must refer for it to Mrs. Franklin's own account.[99] Suffice it that images of the two lines fall on 'corresponding' rows of retinal points, and that the illusory vertical line is the only object capable of throwing such images. A variation of the experiment is this:

"In Fig. 50 the lines are all drawn so as to pass through a common
point. With a little trouble one eye can be put into the position of
this point--it is only necessary that the paper be held so that, with
one eye shut, the other eye sees all the lines leaning neither to
the right nor to the left. After a moment one can fancy the lines to
be vertical staffs standing out of the plane of the paper.'... This
illusion [says Mrs. Franklin] I take to be of purely mental origin.
When a line lies anywhere in a plane passing through the apparent
vertical meridian of one eye, and is looked at with that eye only...
we have no very good means of knowing how it is directed in that
plane.... Now of the lines in nature which lie anywhere within such
a plane, by far the greater number are vertical lines. Hence we are
peculiarly inclined to think that a line which we perceive to be in
such a plane is a vertical line. But to see a whole lot of lines at
once, all ready to throw their images upon the vertical meridian, is a
thing that has hardly ever happened to us, except when they all have
been vertical lines. Hence when that happens we have a still stronger
tendency to think that what we see before us is a group of vertical
lines."

[Illustration: FIG. 50.]

In other words, we see, as always, the most probable object.

      *       *       *       *       *

The foregoing may serve as examples of the first type of illusions mentioned on page 86. I could cite of course many others, but it would be tedious to enumerate all the thaumatropes and zoetropes, dioramas, and juggler's tricks in which they are embodied. In the chapter on Sensation we saw that many illusions commonly ranged under this type are, physiologically considered, of another sort altogether, and that associative processes, strictly so called, have nothing to do with their production.


_Illusions of the Second Type._


We may now turn to illusions of the second of the two types discriminated on page 86. In this type we perceive a wrong object because our mind is full of the thought of it at the time, and any sensation which is in the least degree connected with it touches off, as it were, a train already laid, and gives us a sense that the object is really before us. Here is a familiar example:

"If a sportsman, while shooting woodcock in cover, sees a bird about
the size and color of a woodcock get up and fly through the foliage,
not having time to see more than that it is a bird of such a size
and color, he immediately supplies by inference the other qualities
of a woodcock, and is afterwards disgusted to find that he has shot
a thrush. I have done so myself, and could hardly believe that
the thrush was the bird I had fired at, so complete was my mental
supplement to my visual perception."[100]

As with game, so with enemies, ghosts, and the like. Anyone waiting in a dark place and expecting or fearing strongly a certain object will interpret any abrupt sensation to mean that object's presence. The boy playing 'I spy,' the criminal skulking from his pursuers, the superstitious person hurrying through the woods or past the churchyard at midnight, the man lost in the woods, the girl who tremulously has made an evening appointment with her swain, all are subject to illusions of sight and sound which make their hearts beat till they are dispelled. Twenty times a day the lover, perambulating the streets with his preoccupied fancy, will think he perceives his idol's bonnet before him.

_The Proof-reader's Illusion_. I remember one night in Boston, whilst waiting for a 'Mount Auburn' car to bring me to Cambridge, reading most distinctly that name upon the signboard of a car on which (as I afterwards learned) 'North Avenue' was painted. The illusion was so vivid that I could hardly believe my eyes had deceived me. All reading is more or less performed in this way.

"Practised novel- or newspaper-readers could not possibly get on so
fast if they had to see accurately every single letter of every word
in order to perceive the words. More than half of the words come out
of their mind, and hardly half from the printed page. Were this not
so, did we perceive each letter by itself, typographic errors in
well-known words would never be overlooked. Children, whose ideas
are not yet ready enough to perceive words at a glance, read them
wrong if they are printed wrong, that is, right according to the
way of printing. In a foreign language, although it may be printed
with the same letters, we read by so much the more slowly as we do
not understand, or are unable promptly to perceive the words. But
we notice misprints all the more readily. For this reason Latin and
Greek and, still better, Hebrew works are more correctly printed,
because the proofs are better corrected, than in German works. Of two
friends of mine, one knew much Hebrew, the other little; the latter,
however, gave instruction in Hebrew in a gymnasium; and when he
called the other to help correct his pupils' exercises, it turned out
that he could find out all sorts of little errors better than his
friend, because the latter's perception of the words as totals was too
swift."[101]

_Testimony to personal identity is proverbially fallacious_ for similar reasons. A man has witnessed a rapid crime or accident, and carries away his mental image. Later he is confronted by a prisoner whom he forthwith perceives in the light of that image, and recognizes or 'identifies' as a participant, although he may never have been near the spot. Similarly at the so-called 'materializing séances' which fraudulent mediums give: in a dark room a man sees a gauze-robed figure who in a whisper tells him she is the spirit of his sister, mother, wife, or child, and falls upon his neck. The darkness, the previous forms, and the expectancy have so filled his mind with premonitory images that it is no wonder he perceives what is suggested. These fraudulent 'séances' would furnish most precious documents to the psychology of perception, if they could only be satisfactorily inquired into. In the hypnotic trance any suggested object is sensibly perceived. In certain subjects this happens more or less completely after waking from the trance. It would seem that under favorable conditions a somewhat similar susceptibility to suggestion may exist in certain persons who are not otherwise entranced at all.

This suggestibility is greater in the lower senses than in the higher. A German observer writes:

"We know that a weak smell or taste may be very diversely interpreted
by us, and that the same sensation will now be named as one thing and
the next moment as another. Suppose an agreeable smell of flowers
in a room: A visitor will notice it, seek to recognize what it is,
and at last perceive more and more distinctly that it is the perfume
of roses--until after all he discovers a bouquet of violets. Then
suddenly he recognizes the violet-smell, and wonders how he could
possibly have hit upon the roses.--Just so it is with taste. Try
some meat whose visible characteristics are disguised by the mode of
cooking, and you will perhaps begin by taking it for venison, and end
by being quite certain that it is venison, until you are told that it
is mutton; whereupon you get distinctly the mutton flavor.--In this
wise one may make a person taste or smell what one will, if one only
makes sure that he shall conceive it beforehand as we wish, by saying
to him: 'Doesn't that taste just like, etc.?' or 'Doesn't it smell
just like, etc.?' One can cheat whole companies in this way; announce,
for instance, at a meal, that the meat tastes 'high,' and almost every
one who is not animated by a spirit of opposition will discover a
flavor of putrescence which in reality is not there at all.
"In the sense of _feeling_ this phenomenon is less prominent,
because we get so close to the object that our sensation of it is
never incomplete. Still, examples may be adduced from this sense. On
superficially feeling of a cloth, one may confidently declare it for
velvet, whilst it is perhaps a long-haired cloth; or a person may
perhaps not be able to decide whether he has put on woolen or cotton
stockings, and, trying to ascertain this by the feeling on the skin of
the feet, he may become aware that he gets the feeling of cotton or
wool according as he thinks of the one or the other. When the feeling
in our fingers is somewhat blunted by cold, we notice many such
phenomena, being then more exposed to confound objects of touch with
one another."[102]

High authorities have doubted this power of imagination to falsify present impressions of sense.[103] Yet it unquestionably exists. Within the past fortnight I have been annoyed by a smell, faint but unpleasant, in my library. My annoyance began by an escape of gas from the furnace below stairs. This seemed to get lodged in my imagination as a sort of standard of perception; for, several days after the furnace had been rectified, I perceived the 'same smell' again. It was traced this time to a new pair of India rubber shoes which had been brought in from the shop and laid on a table. It persisted in coming to me for several days, however, in spite of the fact that no other member of the family or visitor noticed anything unpleasant. My impression during part of this time was one of uncertainty whether the smell was imaginary or real; and at last it faded out. Everyone must be able to give instances like this from the smell-sense. When we have paid the faithless plumber for pretending to mend our drains, the intellect inhibits the nose from perceiving the same unaltered odor, until perhaps several days go by. As regards the ventilation or heating of rooms, we are apt to feel for some time as we think we ought to feel. If we believe the ventilator is shut, we feel the room close. On discovering it open, the oppression disappears.

An extreme instance is given in the following extract:

"A patient called at my office one day in a state of great excitement
from the effects of an offensive odor in the horse-car she had come
in, and which she declared had probably emanated from some very sick
person who must have been just carried in it. There could be no doubt
that something had affected her seriously, for she was very pale,
with nausea, difficulty in breathing, and other evidences of bodily
and mental distress. I succeeded, after some difficulty and time,
in quieting her, and she left, protesting that the smell was unlike
anything she had ever before experienced and was something dreadful.
Leaving my office soon after, it so happened that I found her at the
street-corner, waiting for a car: we thus entered the car together.
She immediately called my attention to the same sickening odor which
she had experienced in the other car, and began to be affected the
same as before, when I pointed out to her that the smell was simply
that which always emanates from the straw which has been in stables.
She quickly recognized it as the same, when the unpleasant effects
which arose while she was possessed with another perception of its
character at once passed away."[104]

It is the same with touch. Everyone must have felt the sensible quality change under his hand, as sudden contact with something moist or hairy, in the dark, awoke a shock of disgust or fear which faded into calm recognition of some familiar object? Even so small a thing as a crumb of potato on the table-cloth, which we pick up, thinking it a crumb of bread, feels horrible for a few moments to our fancy, and different from what it is.

Weight or muscular feeling is a sensation; yet who has not heard the anecdote of some one to whom Sir Humphry Davy showed the metal sodium which he had just discovered? "Bless me, how heavy it is!" said the man; showing that his idea of what metals as a class ought to be had falsified the sensation he derived from a very light substance.

In the sense of hearing, similar mistakes abound. I have already mentioned the hallucinatory effect of mental images of very faint sounds, such as distant clock-strokes (above, p. 71). But even when stronger sensations of sound have been present, everyone must recall some experience in which they have altered their acoustic character as soon as the intellect referred them to a different source. The other day a friend was sitting in my room, when the clock, which has a rich low chime, began to strike. "Hollo!" said he, "hear that hand-organ in the garden," and was surprised at finding the real source of the sound. I had myself some years ago a very striking illusion of the sort. Sitting reading late one night, I suddenly heard a most formidable noise proceeding from the upper part of the house, which it seemed to fill. It ceased, and in a moment renewed itself. I went into the hall to listen, but it came no more. Resuming my seat in the room, however, there it was again, low, mighty, alarming, like a rising flood or the _avant-courier_ of an awful gale. It came from all space. Quite startled, I again went into the hall, but it had already ceased once more. On returning a second time to the room, I discovered that it was nothing but the breathing of a little Scotch terrier which lay asleep on the floor. The noteworthy thing is that as soon as I recognized what it was, I was compelled to think it a different sound, and could not then _hear_ it as I had heard it a moment before.

In the anecdotes given by Delbœuf and Reid, this was probably also the case, though it is not so stated. Reid says:

"I remember that once lying abed, and having been put into a fright, I
heard my own heart beat; but I took it to be one knocking at the door,
and arose and opened the door oftener than once, before I discovered
that the sound was in my own breast." (Inquiry, chap. iv. § 1.)

Delbœuf's story is as follows:

"The illustrious P. J. van Beneden, senior, was walking one evening
with a friend along a woody hill near Chaudfontaine. 'Don't you
hear,' said the friend, 'the noise of a hunt on the mountain?' M. van
Beneden listens and distinguishes in fact the giving-tongue of the
dogs. They listen some time, expecting from one moment to another to
see a deer bound by; but the voice of the dogs seems neither to recede
nor approach. At last a countryman comes by, and they ask him who it
is that can be hunting at this late hour. But he, pointing to some
puddles of water near their feet, replies: 'Yonder little animals are
what you hear.' And there there were in fact a number of toads of the
species _Bombinator igneus_.... This batrachian emits at the pairing
season a silvery or rather crystalline note.... Sad and pure, it is a
voice in nowise resembling that of hounds giving chase."[105]

The sense of sight, as we have seen in studying Space, is pregnant with illusions of both the types considered. No sense gives such fluctuating impressions of the same object as sight does. With no sense are we so apt to treat the sensations immediately given as mere signs; with none is the invocation from memory of a _thing_, and the consequent perception of the latter, so immediate. The 'thing' which we perceive always resembles, as we have seen, the object of some absent sensation, usually another optical figure which in our mind has come to be the standard of reality; and it is this incessant reduction of our optical objects to more 'real' forms which has led some authors into the mistake of thinking that the sensations which first apprehend them are originally and natively of no form at all.[106]

Of accidental and occasional illusions of sight many amusing examples might be given. Two will suffice. One is a reminiscence of my own. I was lying in my berth in a steamer listening to the sailors holystone the deck outside; when, on turning my eyes to the window, I perceived with perfect distinctness that the chief-engineer of the vessel had entered my state-room, and was standing looking through the window at the men at work upon the guards. Surprised at his intrusion, and also at his intentness and immobility, I remained watching him and wondering how long he would stand thus. At last I spoke; but getting no reply, sat up in my berth, and then saw that what I had taken for the engineer was my own cap and coat hanging on a peg beside the window. The illusion was complete; the engineer was a peculiar-looking man; and I saw him unmistakably; but after the illusion had vanished I found it hard voluntarily to make the cap and coat look like him at all.

The following story, which I owe to my friend Prof. Hyatt, is of a probably not uncommon class:

"During the winter of 1858, while in Venice, I had the somewhat
peculiar illusion which you request me to relate. I remember the
circumstances very accurately because I have often repeated the story,
and have made an effort to keep all the attendant circumstances clear
of exaggeration. I was travelling with my mother, and we had taken
rooms at a hotel which had been located in an old palace. The room
in which I went to bed was large and lofty. The moon was shining
brightly, and I remember standing before a draped window, thinking
of the romantic nature of the surroundings, remnants of old stories
of knights and ladies, and the possibility that even in that room
itself love-scenes and sanguinary tragedies might have taken place.
The night was so lovely that many of the people were strolling through
the narrow lanes or so-called streets, singing as they went, and I
laid awake for some time listening to these patrols of serenaders,
and of course finally fell asleep. I became aware that some one
was leaning over me closely, and that my own breathing was being
interfered with; a decided feeling of an unwelcome presence of some
sort awakened me. As I opened my eyes I saw, as distinctly as I ever
saw any living person, a draped head about a foot or eighteen inches
to the right, and just above my bed. The horror which took possession
of my young fancy was beyond anything I have ever experienced. The
head was covered by a long black veil which floated out into the
moonlight, the face itself was pale and beautiful, and the lower
part swathed in the white band commonly worn by the nuns of Catholic
orders. My hair seemed to rise up, and a profuse perspiration attested
the genuineness of the terror which I felt. For a time I lay in this
way, and then gradually gaining more command over my superstitious
terrors, concluded to try to grapple with the apparition. It remained
perfectly distinct until I reached at it sharply with my hand, and
then disappeared, to return again, however, as soon as I sank back
into the pillow. The second or third grasp which I made at the head
was not followed by a reappearance, and I then saw that the ghost was
not a real presence, but depended upon the position of my head. If I
moved my eyes either to the left or right of the original position
occupied by my head when I awakened, the ghost disappeared, and by
returning to about the same position, I could make it reappear with
nearly the same intensity as at first. I presently satisfied myself
by these experiments that the illusion arose from the effect of the
imagination, aided by the actual figure made by a visual section of
the moonbeams shining through the lace curtains of the window. If
I had given way to the first terror of the situation and covered
up my head, I should probably have believed in the reality of the
apparition, since I have not by the slightest word, so far as I know,
exaggerated the vividness of my feelings."


THE PHYSIOLOGICAL PROCESS IN PERCEPTION.


Enough, has now been said to prove the general law of perception, which is this, that _whilst part of what we perceive comes through our senses from the object before us, another part_ (and it may be the larger part) _always comes_ (in Lazarus's phrase) _out of our own head_.

At bottom this is only one case (and that the simplest case) of the general fact that our nerve-centres are an organ for reacting on sense-impressions, and that our hemispheres, in particular, are given us in order that records of our private past experience may co-operate in the reaction. Of course such a general way of stating the fact is vague; and all those who follow the current theory of ideas will be prompt to throw this vagueness at it as a reproach. Their way of describing the process goes much more into detail. The sensation, they say, awakens 'images' of other sensations associated with it in the past. These images 'fuse,' or are 'combined' by the Ego with the present sensation into a new product, the percept, etc., etc. Something so indistinguishable from this in practical outcome is what really occurs, that one may seem fastidious in objecting to such a statement, specially if have no rival theory of the elementary processes to propose. And yet, if this notion of images rising and flocking and fusing _be_ mythological (and we have all along so considered it), why should we entertain it unless confessedly as a mere figure of speech? As such, of course, it is convenient and welcome to pass. But if we try to put an exact meaning into it, all we find is that the brain reacts by paths which previous experiences have worn, and makes us usually perceive the probable thing, i.e., the thing by which on previous occasions the reaction was most frequently aroused.

But we can, I think, without danger of being too speculative, be a little more exact than this, and conceive of a physiological reason why the felt quality of an object changes when, instead of being apprehended in a mere sensation, the object is perceived as a thing. All consciousness seems to depend on a certain slowness of the process in the cortical cells. The rapider currents are, the less feeling they seem to awaken. If a region A, then, be so connected with another region B that every current which enters A immediately drains off into B, we shall not be very strongly conscious of the sort of object that A can make us feel. If B, on the contrary, has no such copious channel of discharge, the excitement will linger there longer ere it diffuses itself elsewhere, and our consciousness of the sort of object that B makes us feel will be strong. Carrying this to an ideal maximum, we may say that if A offer _no_ resistance to the transmission forward of the current, and if the current _terminate_ in B, then, no matter what causes may initiate the current, we shall get no consciousness of the object peculiar to A, but on the contrary a vivid sensation of the object peculiar to B. And this will be true though at other times the connection between A and B might lie less open, and every current _then_ entering A might give us a strong consciousness of A's peculiar object. In other words, just in proportion as associations are habitual, will the qualities of the suggested thing tend to substitute themselves in consciousness for those of the thing immediately there; or, more briefly, _just in proportion as an experience is probable will it tend to be directly felt._ In all such experiences the paths lie wide open from the cells first affected to those concerned with the suggested ideas. A circular after-image on the receding wall or ceiling is actually _seen_ as an ellipse, a square after-image of a cross there is seen as slant-legged, etc., because only in the process correlated with the vision of the latter figures do the inward currents find a pause (see the next chapter).

We must remember this when, in dealing with the eye, we come to point out the erroneousness of the principle laid down by Reid and Helmholtz that true sensations can never be changed by the suggestions of experience.

      *       *       *       *       *

A certain illusion of which I have not yet spoken affords an additional illustration of this. _When we will to execute a movement and the movement for some reason does not occur, unless the sensation of the part's_ NOT _moving is a strong one, we are apt to feel as if the movement had actually taken place._ This seems habitually to be the case in anæsthesia of the moving parts. Close the patient's eyes, hold his anæsthetic arm still, and tell him to raise his hand to his head; and when he opens his eyes he will be astonished to find that the movement has not taken place. All reports of anæsthetic cases seem to mention this illusion. Sternberg who wrote on the subject in 1885,[107] lays it down as a law that the intention to move is the same thing as the feeling of the motion. We shall later see that this is false (Chapter XXV); but it certainly may _suggest_ the feeling of the motion with hallucinatory intensity. Sternberg gives the following experiment, which I find succeeds with at least half of those who try it: Rest your palm on the edge of the table with your forefinger hanging over in a position of extreme flexion, and then exert your will to flex it still more. The position of the other fingers makes this impossible, and yet if we do not look to see the finger, we think we feel it move. He quotes from Exner a similar experiment with the jaws: Put some hard rubber or other unindentable obstacle between your back teeth and bite hard: you think you feel the jaw move and the front teeth approach each other, though in the nature of things no movement can occur.[108]--The visual suggestion of the path traversed by the finger-tip as the _locus_ of the movement-feeling in the joint, which we discussed on page 41, is another example of this semi-hallucinatory power of the suggested thing. Amputated people, as we have learned, still feel their lost feet, etc. This is a necessary consequence of the law of specific energies, for if the central region correlated with the foot give rise to any feeling at all it must give rise to the feeling of a foot.[109] But the curious thing is that many of these patients can _will the foot to move_, and when they have done so, distinctly _feel the movement to occur_. They can, to use their own language, 'work' or 'wiggle' their lost toes.[110]

Now in all these various cases we are dealing with data which in normal life are inseparably joined. Of all possible experiences, it is hard to imagine any pair more uniformly and incessantly coupled than the volition to move, on the one hand, and the feeling of the changed position of the parts, on the other. From the earliest ancestors of ours which had feet, down to the present day, the movement of the feet must always have accompanied the will to move them; and here, if anywhere, habit's consequences ought to be found. The process of the willing ought, then, to pour into the process of feeling the command effected, and ought to awaken that feeling in a maximal degree provided no other positively contradictory sensation come in at the same time. In most of us, when the will fails of its effect there is a contradictory sensation. We discern a resistance or the unchanged position of the limb. But neither in anæsthesia nor in amputation can there be any contradictory sensation in the foot to correct us; so imagination has all the force of fact.


'APPERCEPTION.'


In Germany since Herbart's time Psychology has always had a great deal to say about a process called _Apperception_.[111] The incoming ideas or sensations are said to be 'apperceived' by 'masses' of ideas already in the mind. It is plain that the process we have been describing as perception is, at this rate, an apperceptive process. So are all recognition, classing, and naming; and passing beyond these simplest suggestions, all farther thoughts about our percepts are apperceptive processes as well. I have myself not used the word apperception because it has carried very different meanings in the history of philosophy,[112] and 'psychic reaction,' 'interpretation,' 'conception,' 'assimilation,' 'elaboration,' or simply 'thought,' are perfect synonyms for its Herbartian meaning, widely taken. It is, moreover, hardly worth while to pretend to analyze the so-called apperceptive performances beyond the first or perceptive stage, because their variations and degrees are literally innumerable. 'Apperception' is a name for the sum-total of the effects of what we have studied as association; and it is obvious that the things which a given experience will suggest to a man depend on what Mr. Lewes calls his entire psychostatical conditions, his nature and stock of ideas, or, in other words, his character, habits, memory, education, previous experience, and momentary mood. We gain no insight into what really occurs either in the mind or in the brain by calling all these things the 'apperceiving mass,' though of course this may upon occasion be convenient. On the whole I am inclined to think Mr. Lewes's term of 'assimilation' the most fruitful one yet used.[113]

Professor H. Steinthal has analyzed apperceptive processes with a sort of detail which is simply burdensome.[114] His introduction of the matter may, however, be quoted. He begins with an anecdote from a comic paper.

"In the compartment of a railway-carriage six persons unknown to
each other sit in lively conversation. It becomes a matter of regret
that one of the company must alight at the next station. One of
the others says that he of all things prefers such a meeting with
entirely unknown persons, and that on such occasions he is accustomed
neither to ask who or what his companions may be nor to tell who or
what he is. Another thereupon says that he will undertake to decide
this question, if they each and all will answer him an entirely
disconnected question. They began. He drew five leaves from his
note-book, wrote a question on each, and gave one to each of his
companions with the request that he write the answer below. When the
leaves were returned to him, he turned, after reading them, without
hesitation to the others, and said to the first, 'You are a man of
science'; to the second, 'You are a soldier'; to the third, 'You are a
philologer'; to the fourth, 'You are a journalist'; to the fifth, 'You
are a farmer.' All admitted that he was right, whereupon he got out
and left the five behind. Each wished to know what question the others
had received; and behold, he had given the same question to each. It
ran thus:
"'What being destroys what it has itself brought forth?'
"To this the naturalist had answered, 'vital force'; the soldier,
'war'; the philologist, 'Kronos'; the publicist, 'revolution'; the
farmer, 'a boar'. This anecdote, methinks, if not true, is at least
splendidly well invented. Its narrator makes the journalist go on to
say: 'Therein consists the joke. Each one answers the first thing that
occurs to him,[115] and that is whatever is most newly related to his
pursuit in life. Every question is a hole-drilling experiment, and the
answer is an opening through which one sees into our interiors.'... So
do we all. We are all able to recognize the clergyman, the soldier,
the scholar, the business man, not only by the cut of their garments
and the attitude of their body, but by what they say and how they
express it. We guess the place in life of men by the interest which
they show and the way in which they show it, by the objects of which
they speak, by the point of view from which they regard things, judge
them, conceive them, in short by their mode of _apperceiving_....
"Every man has one group of ideas which relate to his own person
and interests, and another which is connected with society. Each
has his group of ideas about plants, religion, law, art, etc., and
more especially about the rose, epic poetry, sermons, free trade,
and the like. Thus the mental content of every individual, even of
the uneducated and of children, consists of masses or circles of
knowledge of which each lies within some larger circle, alongside
of others similarly included, and of which each includes smaller
circles within itself.... The perception of a thing like a horse...
is a process between the present horse's picture before our eyes, on
the one hand, and those fused or interwoven pictures and ideas of
all the horses we have ever seen, on the other;... a process between
two factors or momenta, of which one existed before the process and
was an old possession of the mind (the group of ideas, or concept,
namely), whilst the other is but just presented to the mind, and is
the immediately supervening factor (the sense-impression). The former
apperceives the latter; the latter is apperceived by the former. Out
of their combination an apperception-product arises: the knowledge of
the perceived being as a horse. The earlier factor is relatively to
the later one active and _a priori_; the supervening factor is given,
_a posteriori_, passive.... We may then define Apperception as the
movement of two masses of consciousness (Vorstellungsmassen) against
each other so as to produce a cognition.
"The _a priori_ factor we called active, the _a posteriori_ factor
passive, but this is only relatively true.... Although the _a
priori_ moment commonly shows itself to be the more powerful,
apperception-processes can perfectly well occur in which the new
observation transforms or enriches the apperceiving group of ideas. A
child who hitherto has seen none but four-cornered tables apperceives
a round one as a table; but by this the apperceiving mass ('table') is
enriched. To his previous knowledge of tables comes this new feature
that they need not be four-cornered, but may be round. In the history
of science it has happened often enough that some discovery, at the
same time that it was apperceived, i.e. brought into connection
with the system of our knowledge, transformed the whole system. In
principle, however, we must maintain that, although either factor is
both active and passive, the _a priori_ factor is almost always the
more active of the two."[116]

This account of Steinthal's brings out very clearly the _difference between our psychological conceptions and what are called concepts in logic_. In logic a concept is unalterable; but what are popularly called our 'conceptions of things' alter by being used. The aim of 'Science' is to attain conceptions so adequate and exact that we shall never need to change them. There is an everlasting struggle in every mind between the tendency to keep unchanged, and the tendency to renovate, its ideas. Our education is a ceaseless compromise between the conservative and the progressive factors. Every new experience must be disposed of under _some_ old head. The great point is to find the head which has to be least altered to take it in. Certain Polynesian natives, seeing horses for the first time, called them pigs, that being the nearest head. My child of two played for a week with the first orange that was given him, calling it a 'ball.' He called the first whole eggs he saw 'potatoes,' having been accustomed to see his 'eggs' broken into a glass, and his potatoes without the skin. A folding pocket-corkscrew he unhesitatingly called 'bad-scissors.' Hardly any one of us can make new heads easily when fresh experiences come. Most of us grow more and more enslaved to the stock conceptions with which we have once become familiar, and less and less capable of assimilating impressions in any but the old ways. Old-fogyism, in short, is the inevitable terminus to which life sweeps us on. Objects which violate our established habits of 'apperception' are simply not taken account of at all; or, if on some occasion we are forced by dint of argument to admit their existence, twenty-four hours later the admission is as if it were not, and every trace of the unassimilable truth has vanished from our thought. Genius, in truth, means little more than the faculty of perceiving in an unhabitual way.

On the other hand, nothing is more congenial, from babyhood to the end of life, than to be able to assimilate the new to the old, to meet each threatening violator or burster of our well-known series of concepts, as it comes in, see through its unwontedness, and ticket it off as an old friend in disguise. This victorious assimilation of the new is in fact the type of all intellectual pleasure. The lust for it is curiosity. The relation of the new to the old, before the assimilation is performed, is wonder. We feel neither curiosity nor wonder concerning things so far beyond us that we have no concepts to refer them to or standards by which to measure them.[117] The Fuegians, in Darwin's voyage, wondered at the small boats, but took the big ship as a 'matter of course.' Only what we partly know already inspires us with a desire to know more. The more elaborate textile fabrics, the vaster works in metal, to most of us are like the air, the water, and the ground, absolute existences which awaken no ideas. It is a matter of course that an engraving or a copper-plate inscription should possess that degree of beauty. But if we are shown a _pen_-drawing of equal perfection, our personal sympathy with the difficulty of the task makes us immediately wonder at the skill. The old lady admiring the Academician's picture, says to him: "And is it really all done _by hand_?"


IS PERCEPTION UNCONSCIOUS INFERENCE?


A widely-spread opinion (which has been held by such men as Schopenhauer, Spencer, Hartmann, Wundt, Helmholtz, and lately interestingly pleaded for by M. Binet)[118] will have it that _perception should be called a sort of reasoning operation, more or less unconsciously and automatically performed_. The question seems at first a verbal one, depending on how broadly the term reasoning is to be taken. If, every time a present sign suggests an absent reality to our mind, we make an inference; and if every time we make an inference we reason; then perception is indubitably reasoning. Only one sees no room in it for any unconscious part. Both associates, the present sign and the contiguous things which it suggests, are above-board, and no intermediary ideas are required. Most of those who have upheld the thesis in question have, however, made a more complex supposition. What they have meant is that perception is a _mediate_ inference, and that the middle term is unconscious. When the sensation which I have called 'this' (p. 83, _supra_) is felt, they think that some process like the following runs through the mind:

   'This' is M;
   but M is A;
   therefore 'this' is A.[119]

Now there seem no good grounds for supposing this additional wheelwork in the mind. The classification of '_this_' as M is itself an act of perception, and should, if all perception were inference, require a still earlier syllogism for its performance, and so backwards _in infinitum_. The only extrication from this coil would be to represent the process in altered guise, thus:

   'This' is _like those_;
   _Those_ are A;
   Therefore 'this' is A.

The major premise here involves no association by contiguity, no _naming_ of _those_ as M, but only a suggestion of unnamed similar images, a recall of analogous past sensations with which the characters that make up A were habitually conjoined. But here again, what grounds of fact are there for admitting this recall? We are quite unconscious of any such images of the past. And the conception of all the forms of association as resultants of the elementary fact of habit-worn paths in the brain makes such images entirely superfluous for explaining the phenomena in point. Since the brain-process of 'this,' the sign of A, has repeatedly been aroused in company with the process of the full object A, direct paths of irradiation from the one to the other must be already established. And although roundabout paths may also be possible, as from 'this' to 'those,' and then from 'those' to 'A' (paths which would lead to practically the same conclusion as the straighter ones), yet there is no ground whatever for assuming them to be traversed now, especially since appearances point the other way. In _explicit_ reasoning, such paths are doubtless traversed; in perception they are in all probability closed. So far, then, from perception being a species of reasoning properly so called, both it and reasoning are co-ordinate varieties of that deeper sort of process known psychologically as the association of ideas, and physiologically as the law of habit in the brain. _To call perception unconscious reasoning is thus either a useless metaphor, or a positively misleading confusion between two different things._

      *       *       *       *       *

One more point and we may leave the subject of Perception. _Sir Wm. Hamilton thought that he had discovered a 'great law'_ which had been wholly overlooked by psychologists, and which, 'simple and universal,' is this: "Knowledge and Feeling,--Perception and Sensation, though always coexistent, are always in the inverse ratio of each other." Hamilton wrote as if perception and sensation were two coexistent elements entering into a single state of consciousness. Spencer refines upon him by contending that they are two mutually exclusive _states_ of consciousness, not two elements of a single state. If sensation be taken, as both Hamilton and Spencer mainly take it in this discussion, to mean the feeling of _pleasure_ or _pain_, there is no doubt that the law, however expressed, is true; and that the mind which is strongly conscious of the pleasantness or painfulness of an experience is _ipso facto_ less fitted to observe and analyze its outward cause.[120] Apart from pleasure and pain, however, the law seems but a corollary of the fact that the more concentrated a state of consciousness is, the more vivid it is. When feeling a color, or listening to a tone _per se_, we get it more intensely, notice it better, than when we are aware of it merely as one among many other properties of a total object. The more diffused cerebral excitement of the perceptive state is probably incompatible with quite as strong an excitement of separate parts as the sensational state comports. So we come back here to our own earlier discrimination between the perceptive and the sensational processes, and to the examples which we gave on pp. 80, 81.[121]

HALLUCINATIONS.


Between normal perception and illusion we have seen that there is no break, the _process_ being identically the same in both. The last illusions we considered might fairly be called hallucinations. We must now consider the false perceptions more commonly called by that name.[122] In ordinary parlance hallucination is held to differ from illusion in that, whilst there is an object really there in illusion, _in hallucination there is no objective stimulus at all_. We shall presently see that this supposed absence of objective stimulus in hallucination is a mistake, and that hallucinations are often only _extremes_ of the perception process, in which the secondary cerebral reaction is out of all normal proportion to the peripheral stimulus which occasions the activity. Hallucinations usually appear abruptly and have the character of being forced upon the subject. But they possess various degrees of apparent _objectivity_. One mistake _in limine_ must be guarded against. They are often talked of as mental _images_ projected outwards by mistake. But where an hallucination is complete, it is much more than a mental image. _An hallucination is a strictly sensational form of consciousness, as good and true a sensation as if there were a real object there._ The object happens not to be there, that is all.

The milder degrees of hallucination have been designated as _pseudo-hallucinations_. Pseudo-hallucinations and hallucinations have been sharply distinguished from each other only within a few years. Dr. Kandinsky writes of their difference as follows:

"In carelessly questioning a patient we may confound his
pseudo-hallucinatory perceptions with hallucinations. But to the
unconfused consciousness of the patient himself, even though he be
imbecile, the identification of the two phenomena is impossible,
at least in the sphere of vision. At the moment of having a
pseudo-hallucination of sight, the patient feels himself in an
entirely different relation to this subjective sensible appearance,
from that in which he finds himself whilst subject to a true visual
hallucination. The latter is reality itself; the former, on the
contrary, remains always a subjective phenomenon which the individual
commonly regards either as sent to him as a sign of God's grace, or
as artificially induced by his secret persecutors.... If he knows by
his _own experience_ what a genuine hallucination is, it is quite
impossible for him to mistake the pseudo-hallucination for it.... A
concrete example will make the difference clear:
"Dr. N. L.... heard one day suddenly amongst the voices of his
persecutors ('coming from a hollow space in the midst of the wall') a
rather loud voice impressively saying to him: 'Change your national
allegiance.' Understanding this to mean that his only hope consisted
in ceasing to be subject to the Czar of Russia, he reflected a moment
what allegiance would be better, and resolved to become an English
subject. At the same moment he saw a pseudo-hallucinatory lion of
natural size, which appeared and quickly laid its fore-paws on his
shoulders. He had a lively feeling of these paws as a tolerably
painful local pressure (complete hallucination of touch). Then the
same voice from the wall said: 'Now you have a lion--now you will
rule,' whereupon the patient recollected that the lion was the
national emblem of England. The lion appeared to L. very distinct
and vivid, but he nevertheless remained conscious, as he afterwards
expressed it, that he saw the animal, not with his bodily but with
his mental eyes. (After his recovery he called analogous apparitions
by the name of 'expressive-plastic ideas.') Accordingly he felt no
terror, even though he felt the contact of the claws.... Had the lion
been a complete hallucination, the patient, as he himself remarked
after recovery, would have felt great fear, and very likely screamed
or taken to flight. Had it been a simple image of the fancy he would
not have connected it with the voices, of whose objective reality he
was at the time quite convinced."[123]

From ordinary images of memory and fancy, pseudo-hallucinations differ in being much more vivid, minute, detailed, steady, abrupt, and spontaneous, in the sense that all feeling of our own activity in producing them is lacking. Dr. Kandinsky had a patient who, after taking opium or haschisch, had abundant pseudo-hallucinations and hallucinations. As he also had strong visualizing power and was an educated physician, the three sorts of phenomena could be easily compared. Although projected outwards (usually not farther than the limit of distinctest vision, a foot or so) the pseudo-hallucinations _lacked the character of objective reality_ which the hallucinations possessed, but, unlike the pictures of imagination, it was almost impossible to produce them at will. Most of the 'voices' which people hear (whether they give rise to delusions or not) are pseudo-hallucinations. They are described as '_inner_' voices, although their character is entirely unlike the inner speech of the subject with himself. I know two persons who hear such inner voices making unforeseen remarks whenever they grow quiet and listen for them. They are a very common incident of delusional insanity, and at last grow into vivid hallucinations. The latter are comparatively frequent occurrences in sporadic form; and certain individuals are liable to have them often. From the results of the 'Census of Hallucinations,' which was begun by Edmund Gurney, it would appear that, roughly speaking, one person at least in every ten is likely to have had a vivid hallucination at some time in his life.[124] The following cases from healthy people will give an idea of what these hallucinations are:

"When a girl of eighteen, I was one evening engaged in a very
painful discussion with an elderly person. My distress was so great
that I took up a thick ivory knitting-needle that was lying on the
mantelpiece of the parlor and broke it into small pieces as I talked.
In the midst of the discussion I was very wishful to know the opinion
of a brother with whom I had an unusually close relationship. I turned
round and saw him sitting at the further side of a centre-table, with
his arms folded (an unusual position with him), but, to my dismay, I
perceived from the sarcastic expression of his mouth that he was not
in sympathy with me, was not 'taking my side,' as I should then have
expressed it. The surprise cooled me, and the discussion was dropped.
"Some minutes after, having occasion to speak to my brother, I turned
towards him, but he was gone. I inquired when he left the room,
and was told that he had not been in it, which I did not believe,
thinking that he had come in for a minute and had gone out without
being noticed. About an hour and a half afterwards he appeared, and
convinced me, with some trouble, that he had never been near the house
that evening. He is still alive and well."

Here is another case:

"One night in March 1873 or '74, I cannot recollect which year, I
was attending on the sick-bed of my mother. About eight o'clock in
the evening I went into the dining-room to fix a cup of tea, and on
turning from the sideboard to the table, on the other side of the
table before the fire, which was burning brightly, as was also the
gas, I saw standing with his hand clasped to his side in true military
fashion a soldier of about thirty years of age, with dark, piercing
eyes looking directly into mine. He wore a small cap with standing
feather; his costume was also of a soldierly style. He did not strike
me as being a spirit, ghost, or anything uncanny, only a living man;
but after gazing for fully a minute I realized that it was nothing
of earth, for he neither moved his eyes nor his body, and in looking
closely I could see the fire beyond. I was of course startled, and yet
did not run out of the room. I felt stunned. I walked out rapidly,
however, and turning to the servant in the hall asked her if she saw
anything. She said not. I went into my mother's room and remained
talking for about an hour, but never mentioned the above subject for
fear of exciting her, and finally forgot it altogether, returning to
the dining-room, still in forgetfulness of what had occurred, but
repeating, as above, the turning from sideboard to table in act of
preparing more tea. I looked casually towards the fire, and there I
saw the soldier again. This time I was entirely alarmed, and fled from
the room in haste. I called to my father, but when he came he saw
nothing."

Sometimes more than one sense is affected. The following is a case:

"In response to your request to write out my experience of Oct. 30,
1886, I will inflict on you a letter.
"On the day above mentioned, Oct. 30, 1886, I was in ----, where I
was teaching. I had performed my regular routine work for the day,
and was sitting in my room working out trigonometrical formulæ. I
was expecting every day to hear of the confinement of my wife, and
naturally my thoughts for some time had been more or less with her.
She was, by the way, in B----, some fifty miles from me.
"At the time, however, neither she nor the expected event was in my
mind; as I said, I was working out trigonometrical formulæ, and I had
been working on trigonometry the entire evening. About eleven o'clock,
as I sat there buried in sines, cosines, tangents, cotangents,
secants, and cosecants, I felt very distinctly upon my left shoulder
a touch, and a slight shake, as if somebody had tried to attract my
attention by other means and had failed. Without rising I turned my
head, and there between me and the door stood my wife, dressed exactly
as I last saw her, some five weeks before. As I turned she said: 'It
is a little Herman; he has come.' Something more was said, but this
is the only sentence I can recall. To make sure that I was not asleep
and dreaming, I rose from the chair, pinched myself and walked toward
the figure, which disappeared immediately as I rose. I can give no
information as to the length of time occupied by this episode, but
I know I was awake, in my usual good health. The touch was very
distinct, the figure was absolutely perfect, stood about three feet
from the door, which was closed, and had not been opened during the
evening. The sound of the voice was unmistakable, and I should have
recognized it as my wife's voice even if I had not turned and had not
seen the figure at all. The tone was conversational, just as if she
would have said the same words had she been actually standing there.
"In regard to myself, I would say, as I have already intimated, I was
in my usual good health; I had not been sick before, nor was I after
the occurrence, not so much as a headache having afflicted me.
"Shortly after the experience above described, I retired for the night
and, as I usually do, slept quietly until morning. I did not speculate
particularly about the strange appearance of the night before, and
though I thought of it some, I did not tell anybody. The following
morning I rose, not conscious of having dreamed anything, but I was
very firmly impressed with the idea that there was something for me
at the telegraph-office. I tried to throw off the impression, for so
far as I knew there was no reason for it. Having nothing to do, I went
out for a walk; and to help throw off the impression above noted, I
walked away from the telegraph-office. As I proceeded, however, the
impression became a conviction, and I actually turned about and went
to the very place I had resolved not to visit, the telegraph-office.
The first person I saw on arriving at said office was the
telegraph-operator, who being on terms of intimacy with me, remarked:
'Hello, papa, I've got a telegram for you.' The telegram announced the
birth of a boy, weighing nine pounds, and that all were doing well.
Now, then, I have no theory at all about the events narrated above;
I never had any such experience before nor since; I am no believer
in spiritualism, am not in the least superstitious, know very little
about 'thought-transference,' 'unconscious cerebration,' etc., etc.,
but I am absolutely certain about what I have tried to relate.
"In regard to the remark which I heard, 'It is a little Herman,' etc.;
I would add that we had previously decided to call the child, if a
boy, _Herman_--my own name, by the way."[125]

The hallucination sometimes carries a change of the general consciousness with it, so as to appear more like a sudden lapse into a dream. The following case was given me by a man of 43, who had never anything resembling it before:

"While sitting at my desk this A. M. reading a circular of the Loyal
Legion a very curious thing happened to me, such as I have never
experienced. It was perfectly real, so real that it took some minutes
to recover from. It seems to me like a direct intromission into
some other world. I never had anything approaching it before save
when dreaming at night. I was wide awake, of course. But this was
the feeling. I had only just sat down and become interested in the
circular, when I seemed to lose myself for a minute and then found
myself in the top story of a high building very white and shining and
clean, with a noble window immediately at the right of where I sat.
Through this window I looked out upon a marvellous reach of landscape
entirely new. I never had before such a sense of infinity in nature,
such superb stretches of light and color and _cleanness_. I know that
for the space of three minutes I was entirely lost, for when I began
to come to, so to speak,--sitting in that other world, I debated
for three or four minutes more as to which was dream and which was
reality. Sitting there I got a faint sense of C.... [the town in which
the writer was], away off and dim at first. Then I remember thinking
'Why, I used to live in C....; perhaps I am going back.' Slowly
C.... did come back, and I found myself at my desk again. For a few
minutes the process of determining where I was was very funny. But the
whole experience was perfectly delightful, there was such a sense of
brilliancy and clearness and lightness about it. I suppose it lasted
in all about seven minutes or ten minutes."

The hallucinations of fever-delirium are a mixture of pseudo-hallucination, true hallucination, and illusion. Those of opium, hasheesh, and belladonna resemble them in this respect. The following vivid account of a fit of hasheesh-delirium has been given me by a friend:

"I was reading a newspaper, and the indication of the approaching
delirium was an inability to keep my mind fixed on the narrative.
Directly I lay down upon a sofa there appeared before my eyes several
rows of human hands, which oscillated for a moment, revolved and
then changed to spoons. The same motions were repeated, the objects
changing to wheels, tin soldiers, lamp-posts, brooms, and countless
other absurdities. This stage lasted about ten minutes, and during
that time it is safe to say that I saw at least a thousand different
objects. These whirling images did not appear like the realities of
life, but had the character of the secondary images seen in the eye
after looking at some brightly-illuminated object. A mere suggestion
from the person who was with me in the room was sufficient to call
up an image of the thing suggested, while without suggestion there
appeared all the common objects of life and many unreal monstrosities,
which it is absolutely impossible to describe, and which seemed to be
creations of the brain.
"The character of the symptoms changed rapidly. A sort of wave seemed
to pass over me, and I became aware of the fact that my pulse was
beating rapidly. I took out my watch, and by exercising considerable
will-power managed to time the heart-beats, 135 to the minute.
"I could feel each pulsation through my whole system, and a curious
twitching commenced, which no effort of the mind could stop.
"There were moments of apparent lucidity, when it seemed as if I could
see within myself, and watch the pumping of my heart. A strange fear
came over me, a certainty that I should never recover from the effects
of the opiate, which was as quickly followed by a feeling of great
interest in the experiment, a certainty that the experience was the
most novel and exciting that I had ever been through.
"My mind was in an exceedingly impressionable state. Any place
thought of or suggested appeared with all the distinctness of the
reality. I thought of the Giant's Causeway in Staffa, and instantly
I stood within the portals of Fingal's Cave. Great basaltic columns
rose on all sides, while huge waves rolled through the chasm and
broke in silence upon the rocky shore. Suddenly there was a roar and
blast of sound, and the word 'Ishmaral' was echoing up the cave.
At the enunciation of this remarkable word the great columns of
basalt changed into whirling clothes pins and I laughed aloud at the
absurdity.
"(I may here state that the word 'Ishmaral' seemed to haunt my other
hallucinations, for I remember that I heard it frequently thereafter.)
I next enjoyed a sort of metempsychosis. Any animal or thing that
I thought of could be made the being which held my mind. I thought
of a fox, and instantly I was transformed into that animal. I could
distinctly feel myself a fox, could see my long ears and bushy tail,
and by a sort of introvision felt that my complete anatomy was that
of a fox. Suddenly the point of vision changed. My eyes seemed to be
located at the back of my mouth; I looked out between the parted lips,
saw the two rows of pointed teeth, and, closing my mouth with a snap,
saw--nothing.
"I was next transformed into a bombshell, felt my size, weight, and
thickness, and experienced the sensation of being shot up out of a
giant mortar, looking down upon the earth, bursting and falling back
in a shower of iron fragments.
"Into countless other objects was I transformed, many of them so
absurd that I am unable to conceive what suggested them. For example,
I was a little china doll, deep down in a bottle of olive oil, next
moment a stick of twisted candy, then a skeleton inclosed in a
whirling coffin, and so on _ad infinitum_.
"Towards the end of the delirium the whirling images appeared
again, and I was haunted by a singular creation of the brain, which
reappeared every few moments. It was an image of a double-faced doll,
with a cylindrical body running down to a point like a peg-top.
"It was always the same, having a sort of crown on its head, and
painted in two colors, green and brown, on a background of blue. The
expression of the Janus-like profiles was always the same, as were the
adornments of the body. After recovering from the effects of the drug
I could not picture to myself exactly how this singular monstrosity
appeared, but in subsequent experiences I was always visited by this
phantom, and always recognized every detail of its composition. It was
like visiting some long-forgotten spot and seeing some sight that had
faded from the memory, but which appeared perfectly familiar as soon
as looked upon.
"The effects of the drug lasted about an hour and a half, leaving me a
trifle tipsy and dizzy; but after a ten-hour sleep I was myself again,
save for a slight inability to keep my mind fixed on any piece of work
for any length of time, which remained with me during most of the next
day."


THE NEURAL PROCESS IN HALLUCINATION.


Examples of these singular perversions of perception might be multiplied indefinitely, but I have no more space. Let us turn to the question of what the physiological process may be to which they are due. It must, of course, consist of an excitement from within of those centres which are active in normal perception, identical in kind and degree with that which real external objects are usually needed to induce. The particular process which currents from the sense-organs arouse would seem under normal circumstances to be arousable in no other way. On p. 72 ff. above, we saw that the centres aroused by incoming peripheral currents are probably identical with the centres used in mere imagination; and that the vividness of the sensational kind of consciousness is probably correlated with a discrete degree of _intensity_ in the process therein aroused. Referring the reader back to that passage and to what was more lately said on p. 103 ff., I now proceed to complete my theory of the perceptive process by an analysis of what may most probably be believed to take place in hallucination strictly so called.

We have seen (p. 75) that the free discharge of cells into each other through associative paths is a likely reason why the maximum intensity of function is not reached when the cells are excited by their neighbors in the cortex. At the end of Chapter XXV we shall return to this conception, and whilst making it still more precise, use it for explaining certain phenomena connected with the will. The idea is that the leakage forward along these paths is too rapid for the inner tension in any centre to accumulate to the maximal explosion-point, unless the exciting currents are greater than those which the various portions of the cortex supply to each other. Currents from the periphery are (as it seems) the only currents whose energy can vanquish the supra-ideational resistance (so to call it) of the cells, and cause the peculiarly intense sort of disintegration with which the sensational quality is linked. _If, however, the leakage forward were to stop,_ the tension inside certain cells might reach the explosion-point, even though the influence which excited them came only from neighboring cortical parts. Let an empty pail with a leak in its bottom, tipped up against a support so that if it ever became full of water it would upset, represent the resting condition of the centre for a certain sort of feeling. Let water poured into it stand for the currents which are its natural stimulus; then the hole in its bottom will, of course, represent the 'paths' by which it transmits its excitement to other associated cells. Now let two other vessels have the function of supplying it with water. One of these vessels stands for the neighboring cortical cells, and can pour in hardly any more water than goes out by the leak. The pail consequently never upsets in consequence of the supply from this source. A current of water passes through it and does work elsewhere, but in the pail itself nothing but what stands for _ideational_ activity is aroused. The other vessel, however, stands for the peripheral sense-organs, and supplies a stream of water so copious that the pail promptly fills up in spite of the leak, and presently _upsets_; in other words, _sensational_ activity is aroused. But it is obvious that if the leak were plugged, the slower stream of supply would also end by upsetting the pail.

To apply this to the brain and to thought, if we take a series of processes A B C D E, associated together in that order, and suppose that the current through them is very fluent, there will be little intensity anywhere until, perhaps, a pause occurs at E. But the moment the current is blocked anywhere, say between C and D, the process in C must grow more intense, and might even be conceived to explode so as to produce a sensation in the mind instead of an idea.

It would seem that some hallucinations are best to be explained in this way. We have in fact a regular series of facts which can all be formulated under the single law that _the substantive strength of a state of consciousness bears an inverse proportion to its suggestiveness_. It is the halting-places of our thought which are occupied with distinct imagery. Most of the words we utter have no time to awaken images at all; they simply awaken the following words. But when the sentence _stops_, an image dwells for awhile before the mental eye (see Vol. I. p. 243). Again, whenever the associative processes are reduced and impeded by the approach of unconsciousness, as in falling asleep, or growing faint, or becoming narcotized, we find a concomitant increase in the intensity of whatever partial consciousness may survive. In some people what M. Maury has called 'hypnagogic' hallucinations[126] are the regular concomitant of the process of falling asleep. Trains of faces, landscapes, etc., pass before the mental eye, first as fancies, then as pseudo-hallucinations, finally as full-fledged hallucinations forming dreams. If we regard association-paths as paths of drainage, then the shutting off of one after another of them as the encroaching cerebral paralysis advances ought to act like the plugging of the hole in the bottom of the pail, and make the activity more intense in those systems of cells that retain any activity at all. The level rises because the currents are not drained away, until at last the full sensational explosion may occur.

The usual explanation of hypnagogic hallucinations is that they are ideas deprived of their ordinary _reductives_. In somnolescence, sensations being extinct, the mind, it is said, then having no stronger things to compare its ideas with, ascribes to these the fulness of reality. At ordinary times the objects of our imagination are reduced to the _status_ of subjective facts by the ever-present contrast of our sensations with them. Eliminate the sensations, however, this view supposes, and the 'images' are forthwith 'projected' into the outer world and appear as realities. Thus is the illusion of dreams also explained. This, indeed, after a fashion gives an account of the facts.[127] And yet it certainly fails to explain the extraordinary vivacity and completeness of so many of our dream-fantasms. The process of 'imagining' must (in these cases at least[128]) be not merely relatively, but absolutely and in itself more intense than at other times. The fact is, it is not a process of imagining, but a genuine sensational process; and the theory in question is therefore false as far as that point is concerned.

Dr. Hughlings Jackson's explanation of the epileptic seizure is acknowledged to be masterly. It involves principles exactly like those which I am bringing forward here. The 'loss of consciousness' in epilepsy is due to the most highly organized brain-processes being exhausted and thrown out of gear. The less organized (more instinctive) processes, ordinarily inhibited by the others, are then exalted, so that we get as a mere consequence of relief from the inhibition, the meaningless or maniacal action which so often follows the attack.[129]

Similarly the _subsultus tendinorum_ or jerking of the muscles which so often startles us when we are on the point of falling asleep, may be interpreted as due to the rise (in certain lower motor centres) of the ordinary 'tonic' tension to the explosion-point, when the inhibition commonly exerted by the higher centres falls too suddenly away.

      *       *       *       *       *

One possible condition of hallucination then stands revealed, whatever other conditions there may be. _When the normal paths of association between a centre and other centres are thrown out of gear, any activity which may exist in the first centre tends to increase in intensity until finally the point may be reached at which the last inward resistance is overcome, and the full sensational process explodes._[130] Thus it will happen that causes of an amount of activity in brain-cells which would ordinarily result in a weak consciousness may produce a very strong consciousness when the overflow of these cells is stopped by the torpor of the rest of the brain. A slight peripheral irritation, then, if it reaches the centres of consciousness at all during sleep, will give rise to the dream of a violent sensation. All the books about dreaming are full of anecdotes which illustrate this. For example, M. Maury's nose and lips are tickled with a feather while he sleeps. He dreams he is being tortured by having a pitch-plaster applied to his face, torn off, lacerating the skin of nose and lips. Descartes, on being bitten by a flea, dreams of being run through by a sword. A friend tells me, as I write this, of his hair changing its position in his forehead just as he 'dozed off' in his chair a few days since. Instantly he dreamed that some one had struck him a blow. Examples can be quoted _ad libitum_, but these are enough.[131]

We seem herewith to have an explanation for a certain number of hallucinations. _Whenever the normal forward irradiation of intra-cortical excitement through association-paths is checked, any accidental spontaneous activity or any peripheral stimulation (however inadequate at other times) by which a brain-centre may be visited, sets up a process of full sensational intensity therein._

      *       *       *       *       *

In the hallucinations artificially produced in hypnotic subjects, some degree of peripheral excitement seems usually to be required. The brain is asleep as far as its own spontaneous thinking goes, and the words of the 'magnetizer' then awaken a cortical process which drafts off into itself any currents of a related sort which may come in from the periphery, resulting in a vivid objective perception of the suggested thing. Thus, point to a dot on a sheet of paper, and call it 'General Grant's photograph,' and your subject will see a photograph of the General there instead of the dot. The dot gives objectivity to the appearance, and the suggested notion of the General gives it form. Then magnify the dot by a lens; double it by a prism or by nudging the eyeball; reflect it in a mirror; turn it upside down; or wipe it out; and the subject will tell you that the 'photograph' has been enlarged, doubled, reflected, turned about, or made to disappear. In M. Binet's language,[132] the dot is the outward _point de repère_ which is needed to give objectivity to your suggestion, and without which the latter will only produce a _conception_ in the subject's mind.[133] M. Binet has shown that such a peripheral _point de repère_ is used in an enormous number, not only of hypnotic hallucinations, but of hallucinations of the insane. These latter are often _unilateral_; that is, the patient hears the voices always on one side of him, or sees the figure only when a certain one of his eyes is open. In many of these cases it has been distinctly proved that a morbid irritation in the internal ear, or an opacity in the humors of the eye, was the starting point of the current which the patient's diseased acoustic or optical centres clothed with their peculiar products in the way of ideas. _Hallucinations produced in this way are_ 'ILLUSIONS' _and M. Binet's theory, that all hallucinations must start in the periphery, may be called an attempt to reduce hallucination and illusion to one physiological type,_ the type, namely, to which normal perception belongs. In every case, according to M. Binet, whether of perception, of hallucination, or of illusion, we get the sensational vividness by means of a current from the peripheral nerves. It may be a mere trace of a current. But that trace is enough to kindle the maximal or supra-ideational process so that the object perceived will have the character of _externality_. What the _nature_ of the object shall be will depend wholly on the particular system of paths in which the process is kindled. Part of the thing in all cases comes from the sense-organ, the rest is furnished by the mind. But we cannot by introspection distinguish between these parts; and our only formula for the result is that the brain has _reacted on_ the impression in the normal way. Just so in the dreams which we have considered, and in the hallucinations of which M. Binet tells, we can only say that the brain has _reacted_ in an abnormal way.

_M. Binet's theory accounts indeed for a multitude of cases, but certainly not for all._ The prism does not always double the false appearance,[134] nor does the latter always disappear when the eyes are closed. Dr. Hack Tuke[135] gives several examples in sane people of well-exteriorized hallucinations which did not respond to Binet's tests; and Mr. Edmund Gurney[136] gives a number of reasons why intensity in a cortical process may be expected to result from local pathological activity just as much as its peculiar nature does. For Binet, an abnormally or exclusively active part of the cortex gives the _nature_ of what shall appear, whilst a peripheral sense-organ alone can give the _intensity_ sufficient to make it appear projected into real space. But since this intensity is after all but a matter of degree, one does not see why, under rare conditions, the degree in question _might_ not be attained by inner causes exclusively. In that case we should have certain hallucinations centrally initiated alongside of the peripherally initiated hallucinations, which are the only sort that M. Binet's theory allows. _It seems probable on the whole, therefore, that centrally initiated hallucinations can exist._ How often they do exist is another question. The existence of hallucinations which affect more than one sense is an argument for central initiation. For grant that the thing seen may have its starting point in the outer world, the voice which it is heard to utter must be due to an influence from the visual region, i.e. must be of central origin.

Sporadic cases of hallucination, visiting people only once in a lifetime (which seem to be by far the most frequent type), are on any theory hard to understand in detail. They are often extraordinarily complete; and the fact that many of them are reported as _veridical_, that is, as coinciding with real events, such as accidents, deaths, etc., of the persons seen, is an additional complication of the phenomenon. The first really scientific study of hallucination in all its possible bearings, on the basis of a large mass of empirical material, was begun by Mr. Edmund Gurney and is continued by other members of the Society for Psychical Research; and the 'Census' is now being applied to several countries under the auspices of the International Congress of Experimental Psychology. It is to be hoped that out of these combined labors something solid will eventually grow. The facts shade off into the phenomena of motor automatism, trance, etc.; and nothing but a wide comparative study can give really instructive results.[137]

_The part played by the peripheral sense-organ_ in hallucination is just as obscure as we found it in the case of imagination. The things seen often seem opaque and hide the background upon which they are projected. It does not follow from this, however, that the retina is actually involved in the vision. A contrary process going on in the visual centres would prevent the retinal impression made by the outer realities from being felt, and this would in mental terms be equivalent to the hiding of them by the imaginary figure. The negative after-images of mental pictures reported by Meyer and Féré, and the negative after-images of hypnotic hallucinations reported by Binet and others so far constitute the only evidence there is for the retina being involved. But until these after-images are explained in some other way we must admit the possibility of a centrifugal current from the optical centres downwards into the peripheral organ of sight, paradoxical as the course of such a current may appear.

'PERCEPTION-TIME.'

_The time which the perceptive process occupies_ has been inquired into by various experimenters. Some call it perception-time, some choice-time, some discrimination-time. The results have been already given in Chapter XIII (vol. I, p. 523 ff.), to which the reader is consequently referred.

Dr. Romanes gives an interesting variation of these time-measurements. He found[138]

"an astonishing difference between different individuals with respect
to the rate at which they are able to _read_. Of course reading
implies enormously intricate processes of perception both of the
sensuous and of the intellectual order; but if we choose for these
observations persons who have been accustomed to read much, we may
consider that they are all very much on a par with respect to the
amount of practice which they have had, so that the differences in
their rates of reading may fairly be attributed to real differences in
their rates of forming complex perceptions in rapid succession, and
not to any merely accidental differences arising from greater or less
facility acquired by special practice.
"My experiments consisted in marking a brief printed paragraph in a
book which had never been read by any of the persons to whom it was
to be presented. The paragraph, which contained simple statements of
simple facts, was marked on the margin with pencil. The book was then
placed before the reader open, the page, however, being covered with
a sheet of paper. Having pointed out to the reader upon this sheet of
paper what part of the underlying page the marked paragraph occupied,
I suddenly removed the sheet of paper with one hand, while I started a
chronograph with the other. Twenty seconds being allowed for reading
the paragraph (ten lines octavo), as soon as the time was up I again
suddenly placed the sheet of paper over the printed page, passed the
book on to the next reader, and repeated the experiment as before.
Meanwhile, the first reader, the moment after the book had been
removed, wrote down all that he or she could remember having read. And
so on with all the other readers.
"Now the results of a number of experiments conducted on this method
were to show, as I have said, astonishing differences in the _maximum_
rate of reading which is possible to different individuals, all of
whom have been accustomed to extensive reading. That is to say, the
difference may amount to 4 to 1; or, otherwise stated, in a given time
one individual may be able to read four times as much as another.
Moreover, it appeared that there was no relationship between slowness
of reading and power of assimilation; on the contrary, when all the
efforts are directed to assimilating as much as possible in a given
time, the rapid readers (as shown by their written notes) usually give
a better account of the portions of the paragraph which have been
compassed by the slow readers than the latter are able to give; and
the most rapid reader I have found is also the best at assimilating. I
should further say that there is no relationship between rapidity of
perception as thus tested and intellectual activity as tested by the
general results of intellectual work; for I have tried the experiment
with several highly distinguished men in science and literature, most
of whom I found to be slow readers."[139]
      *       *       *       *       *

[83] The word Perception, however, has been variously used. For historical notices, see Hamilton's Lectures on Metaphysics, ii. 96. For Hamilton perception is 'the consciousness of external objects' (_ib._ 28). Spencer defines it oddly enough as "a discerning of the relation or relations between _states of consciousness_ partly presentative and partly representative; which states of consciousness must be themselves known to the extent involved in the knowledge of their relations" (Psychol., § 355).

[84] Analysis, i. 97.

[85] Theory of Vision, 51.

[86] The educative process is particularly obvious in the case of the ear, for all sudden sounds seem alarming to babies. The familiar noises of house and street keep them in constant trepidation until such time as they have either learned the objects which emit them, or have become blunted to them by frequent experience of their innocuity.

[87] Outlines, p. 153.

[88] Cf. Helmholtz, Optik, pp. 433, 723, 728, 772; and Spencer, Psychology, vol. ii. p. 249, note.

[89] The more or less geometrically regular phantasms which are produced by pressure on the eyeballs, congestion of the head, inhalation of anæsthetics, etc., might again be cited to prove that faint and vague excitements of sense-organs are transformed into figured objects by the brain, only the facts are not quite clearly interpretable; and the figuring may possibly be due to some retinal peculiarity, as yet unexplored. Beautiful patterns, which would do for wall-papers, succeed each other when the eyeballs are long pressed. Goethe's account of his own phantasm of a flower is well known. It came in the middle of his visual field whenever he closed his eyes and depressed his head, "unfolding itself and developing from its interior new flowers, formed of colored or sometimes green leaves, not natural but of fantastic forms, and symmetrical as the rosettes of sculptors," etc. (quoted in Müller's Physiology, Baly's tr., p. 1397). The fortification- and zigzag-patterns, which are well-known appearances in the field of view in certain functional disorders, have characteristics (steadiness, coerciveness, blotting out of other objects) suggestive of a retinal origin--this is why the entire class of phenomena treated of in this note seem to me still doubtfully connected with the cerebral factor in perception of which the text treats.--I copy from Taine's book on Intelligence (vol. i. p. 61) the translation of an interesting observation by Prof. M. Lazarus, in which the same effect of an after-image is seen. Lazarus himself proposes the name of 'visionary illusions' for such modifications of ideal pictures by peripheral stimulations (Lehre von den Sinnestäuschungen, 1867, p. 19). "I was on the Kaltbad terrace at Rigi, on a very clear afternoon, and attempting to make out the Waldbruder, a rock which stands out from the midst of the gigantic wall of mountains surrounding it, on whose summits we see like a crown the glaciers of Titlis, Uri-Rothsdock, etc. I was looking alternately with the naked eye and with a spy-glass; but could not distinguish it with the naked eye. For the space of six to ten minutes I had gazed steadfastly upon the mountains, whose color varied according to their several altitudes or declivities between violet, brown, and dark green, and I had fatigued myself to no purpose, when I ceased looking and turned away. At that moment I saw before me (I cannot recollect whether my eyes were shut or open) the figure of an absent friend, like a corpse.... I asked myself at once how I had come to think of my absent friend.--In a few seconds I regained the thread of my thoughts, which my looking for the Waldbruder had interrupted, and readily found that the idea of my friend had by a very simple necessity introduced itself among them. My recollecting him was thus naturally accounted for.--But in addition to this, he had appeared as a corpse. How was this?--At this moment, whether through fatigue or in order to think, I closed my eyes, and found at once the whole field of sight, over a considerable extent, covered with the same corpse-like hue, a greenish-yellow gray. I thought at once that I had here the principle of the desired explanation, and attempted to recall to memory the forms of other persons. And, in fact, these forms too appeared like corpses; standing or sitting, as I wished, all had a corpse-like tint. The persons whom I wished to see did not all appear to me as sensible phantoms; and again, when my eyes were open. I did not see phantoms, or at all events only saw them faintly, of no determined color.--I then inquired how it was that phantoms of persons were affected by and colored like the visual field surrounding them, how their outlines were traced, and if their faces and clothes were of the same color. But it was then too late, or perhaps the influence of reflection and examination had been too powerful. All grew suddenly pale, and the subjective phenomenon, which might have lasted some minutes longer, had disappeared.--It is plain that here an inward reminiscence, arising in accordance with the laws of association, had combined with an optical after-image. The excessive excitation of the periphery of the optic nerve, I mean the long-continued preceding sensation of my eyes when contemplating the color of the mountain, had indirectly provoked a subjective and durable sensation, that of the complementary color; and my reminiscence, incorporating itself with this subjective sensation, became the corpse-like phantom I have described."

[90] Cf. Th. Reid's Intellectual Powers, essay ii. chap. xxii, and A. Binet, in Mind, ix. 206. M. Binet points out the fact that what is fallaciously inferred is always an object of some other sense than the 'this.' 'Optical illusions' are generally errors of touch and muscular sensibility, and the fallaciously perceived object and the experiences which correct it are both tactile in these cases.

[91] The converse illusion is hard to bring about. The points _a_ and _b_, being normally in contact, mean to us the same space, and hence it might be supposed that when simultaneously touched, as by a pair of callipers, we should feel but one object, whilst us a matter of fact we feel two. It should be remarked in explanation of this that an object placed between the two fingers in their normal uncrossed position always awakens the sense of _two contacts_. When the fingers are _pressed together_ we feel _one object_ to be between them. And when the fingers are crossed, and their corresponding points _a_ and _b_ simultaneously _pressed_, we do get something like the illusion of singleness--that is, we get a very doubtful doubleness.

[92] Purkinje, Mach, and Breuer are the authors to whom we mainly owe the explanation of the feeling of vertigo. I have found (American Journal of Otology, Oct. 1882) that in deaf-mutes (whose semi-circular canals or entire auditory nerves must often be disorganized) there very frequently exists no susceptibility to giddiness or whirling.

[93] The involuntary continuance of the eye's motions is not the only cause of the false perception in these cases. There is also a true negative after-image of the original retinal movement-sensations, as we shall see in Chapter XX.

[94] We never, so far as I know, get the converse illusion at a railroad station and believe the other train to move when it is still.

[95] Helmholtz: Physiol. Optik, 365.

[96] Cf. Berkeley's Theory of Vision, §§ 67-79; Helmholtz: Physiologische Optik, pp. 630-1; Lechalas in Revue Philosophique, xxvi. 49.

[97] Physiol. Optik, p. 602.

[98] It seems likely that the strains in the _recti_ muscles have something to do with the vacillating judgment in these atropin cases. The internal recti contract whenever we accommodate. They squint and produce double vision when the innervation for accommodation is excessive. To see singly, when straining the atropinized accommodation, the contraction of our internal _recti_ must be neutralized by a correspondingly excessive contraction of the external _recti_. But this is a sign of the object's recession, etc.

[99] American Journal of Psychology, i. 101 ff.

[100] Romanes, Mental Evolution in Animals, p. 324.

[101] M. Lazarus: Das Leben d. Seele, ii (1857), p. 32. In the ordinary hearing of speech half the words we seem to hear are supplied out of our own head. A language with which we are perfectly familiar is understood, even when spoken in low tones and far off. An unfamiliar language is unintelligible under these conditions. If we do not get a very good seat at a foreign theatre, we fail to follow the dialogue; and what gives trouble to most of us when abroad is not only that the natives speak so fast, but that they speak so indistinctly and so low. The verbal objects for interpreting the sounds by are not alert and ready made in our minds, as they are in our familiar mother-tongue, and do not start up at so faint a cue.

[102] G. H. Meyer, Untersuchungen, etc., pp. 242-8.

[103] Helmholtz, P. O. 438. The question will soon come before us again in the chapter on the Perception of Space.

[104] C. F. Taylor, Sensation and Pain, p. 37 (N. Y., 1882).

[105] Examen Critique de la Loi Psychophysique (1883), p. 61.

[106] Compare A. W Volkmann's essay 'Ueber Ursprüngliches und Erworbenes in den Raumanschauungen,' on p. 139 of his Untersuchungen im Gebiete der Optik; and Chapter xiii of Hering's contribution to Hermann's Handbuch der Physiologie, vol. iii.

[107] In the Proceedings of the American Society for Psychical Research, pp. 253-4, I have tried to account for some of the variations in this consciousness. Out of 140 persons whom I found to feel their lost foot, some did so _dubiously_. "Either they only feel it occasionally, or only when it pains them, or only when they try to move it; or they only feel it when they 'think a good deal about it' and make an effort to conjure it up. When they 'grow inattentive,' the feeling 'flies back' or 'jumps back,' to the stump. Every degree of consciousness, from complete and permanent hallucination down to something hardly distinguishable from ordinary fancy, seems represented in the sense of the missing extremity which these patients say they have. Indeed I have seldom seen a more plausible lot of evidence for the view that imagination and sensation are but differences of vividness in an identical process than these confessions, taking them altogether, contain. Many patients say they can hardly tell whether they feel or fancy the limb."

[108] Pflüger's Archiv, xxxvii. 1.

[109] Not all patients have this additional illusion.

[110] I ought to say that in _almost_ all cases the volition is followed by actual contraction of muscles in the _stump_.

[111] Cf. Herbart, Psychol. als. Wissenschaft, § 125.

[112] Compare the historical reviews by K. Lange: Ueber Apperception (Plauen, 1879), pp. 12-14; by Staude in Wundt's Philosophische Studien, i. 149; and by Marty in Vierteljsch. f. wiss. Phil., x. 347 ff.

[113] Problems, vol. i. p. 118 ff.

[114] See his Einleitung in die Psychologie u. Sprachwissenschaft (1881) p. 166 ff.

[115] One of my colleagues, asking himself the question after reading the anecdote, tells me that he replied 'Harvard College,' the faculty of that body having voted, a few days previously, to keep back the degrees of members of the graduating class who might be disorderly on class-day night. W. J.

[116] _Op. cit._ pp. 166-171.

[117] The great maxim in pedagogy is to knit every new piece of knowledge on to a pre-existing curiosity--i.e., to assimilate its matter in some way to what is already known. Hence the advantage of "comparing all that is far off and foreign to something that is near home, of making the unknown plain by the example of the known, and of connecting all the instruction with the personal experience of the pupil.... If the teacher is to explain the distance of the sun from the earth, let him ask.... 'If anyone there in the sun fired off a cannon straight at you, what should you do?' 'Get out of the way' would be the answer. 'No need of that,' the teacher might reply. 'You may quietly go to sleep in your room, and get up again, you may wait till your confirmation-day, you may learn a trade, and grow as old as I am,--_then_ only will the cannon-ball be getting near, _then_ you may jump to one side! See, so great as that is the sun's distance!'" (K. Lange, Ueber Apperception, 1879, p. 76--a charming though prolix little work.)

[118] A. Schopenhauer, Satz vom Grunde, chap. iv. H. Spencer, Psychol., part vi. chaps. ix, x. E. v. Hartmann, Phil. of the Unconscious (B), chaps. vii, viii. W. Wundt, Beiträge, pp. 422 ff.; Vorlesungen, iv, xiii. H. Helmholtz, Physiol. Optik, pp. 430, 447. A. Binet, Psychol. du Raisonnement, chaps. iii, v. Wundt and Helmholtz have more recently 'recanted.' See above, vol i. p. 169 note.

[119] When not all M, but only some M, is A, when, in other words, M is 'undistributed' the conclusion is liable to error. Illusions would thus be _logical fallacies_, if true perceptions were valid syllogisms. They would draw false conclusions from undistributed middle terms.

[120] See Spencer, Psychol., ii. p. 250, note, for a physiological hypothesis to account for this fact.

[121] Here is another good example, taken from Helmholtz's Optics, p. 435: "The sight of a man walking is a familiar spectacle to us. We perceive it as a connected whole, and at most notice the most striking of its peculiarities. Strong attention is required, and a special choice of the point of view, in order to feel the perpendicular and lateral oscillations of such a walking figure. We must choose fitting points or lines in the background with which to compare the positions of its head, but if a distant walking man be looked at through an astronomical telescope (which inverts the object), what a singular hopping and rocking appearance he presents! No difficulty now in seeing the body's oscillations, and many other details of the gait.... But, on the other hand, its total character, whether light or clumsy, dignified or graceful, is harder to perceive than in the upright position."

[122] Illusions and hallucinations must both be distinguished from _delusions_. A delusion is a false opinion about a matter of fact, which need not necessarily involve, though it often does involve, false perceptions of sensible things. We may, for example, have religious delusions, medical delusions, delusions about our own importance, about other peoples' characters, etc., _ad libitum_. The delusions of the insane are apt to affect certain typical forms, often very hard to explain. But in many cases they are certainly theories which the patients invent to account for their abnormal bodily sensations. In other cases they are due to hallucinations of hearing and of sight. Dr. Clouston (Clinical Lectures on Mental Disease, lecture iii _ad fin._) gives the following special delusions as having been found in about a hundred melancholy female patients who were afflicted in this way. There were delusions of

general persecution; being destitute; general suspicion; being followed by the police; being poisoned; being very wicked; being killed; impending death; being conspired against; impending calamity; being defrauded; the soul being lost; being preached against in church; having no stomach; being pregnant; having no inside; having a bone in the throat; having neither stomach nor brains; having lost much money; being covered with vermin; being unfit to live; letters being written about her; that she will not recover; property being stolen; that she is to be murdered; her children being killed; that she is to be boiled alive; having committed theft; that she is to be starved; the legs being made of glass; that the flesh is boiling; having horns on the head; that the head is severed from being chloroformed;

 the body;                        having committed murder;

that children are burning; fear of being hanged; that murders take place around; being called names by person; that it is wrong to take food; being acted on by spirits; being in hell; being a man; being tempted of the devil; the body being transformed; being possessed of the devil; insects coming from the body; having committed an rape being practised on her;

 unpardonable sin;                having a venereal disease;

unseen agencies working; being a fish; her own identity; being dead; being on fire; having committed suicide of the soul.


[123] V. Kandinsky: Kritische u. Klinische Betrachtungen im Gebiete d. Sinnestäuschungen (1886), p. 42.

[124] See Proceedings of Soc. for Psych. Research, Dec. 1889, pp. 7, 183. The International Congress for Experimental Psychology has now charge of the Census, and the present writer is its agent for America.

[125] This case is of the class which Mr. Myers terms 'veridical.' In a subsequent letter the writer informs me that his vision occurred some five hours _before_ the child was born.

[126] Le Sommeil et les Rêves (1865), chaps. iii, iv.

[127] This theory of incomplete rectification of the inner images by their usual reductives is most brilliantly stated by M. Taine in his work on Intelligence, book ii. chap. i.

[128] Not, of course, in all cases, because the cells remaining active are themselves on the way to be overpowered by the general (unknown) condition to which sleep is due.

[129] For a full account of Jackson's theories, see his 'Croonian Lectures' published in the Brit. Med. Journ. for 1884. Cf. also his remarks in the Discussion of Dr. Mercier's paper on Inhibition in 'Brain,' xi. 361.

The loss of vivacity in the images in the process of waking, as well as the gain of it in falling asleep, are both well described by M. Taine, who writes (on Intelligence, i. 50, 58) that often in the daytime, when fatigued and seated in a chair, it is sufficient for him to close one eye with a handkerchief, when, "by degrees, the sight of the other eye becomes vague, and it closes. All external sensations are gradually effaced, or cease, at all events, to be remarked; the internal images, on the other hand, feeble and rapid during the state of complete wakefulness, become intense, distinct, colored, steady, and lasting: there is a sort of ecstasy, accompanied by a feeling of expansion and of comfort. Warned by frequent experience, I know that sleep is coming on, and that I must not disturb the rising vision; I remain passive, and in a few minutes it is complete. Architecture, landscapes, moving figures, pass slowly by, and sometimes remain, with incomparable clearness of form and fulness of being; sleep comes on, and I know no more of the real world I am in. Many times, like M. Maury, I have caused myself to be gently roused at different moments of this state, and have thus been able to mark its characters.--The intense image which seems an external object is but a more forcible continuation of the feeble image which an instant before I recognized as internal; some scrap of a forest, some house, some person which I vaguely imagined on closing my eyes, has in a minute become present to me with full bodily details, so as to change into a complete hallucination. Then, waking up on a hand touching me, I feel the figure decay, lose color, and evaporate: what had appeared a substance is reduced to a shadow.... In such a case, I have often seen, for a passing moment, the image _grow pale_, waste away, and evaporate; sometimes, on opening the eyes, a fragment of landscape or the skirt of a dress appears still to float over the fire-irons or on the black hearth." This persistence of dream-objects for a few moments after the eyes are opened seems to be no extremely rare experience. Many cases of it have been reported to me directly. Compare Müller's Physiology, Baly's tr., p. 945.

[130] I say the 'normal' paths, because hallucinations are not incompatible with _some_ paths of association being left. Some hypnotic patients will not only have hallucinations of objects suggested to them, but will amplify them and act out the situation. But the paths here seem excessively narrow, and the reflections which ought to make the hallucination incredible do not occur to the subject's mind. In general, the narrower a train of 'ideas' is, the vivider the consciousness is of each. Under ordinary circumstances, the entire brain probably plays a part in draining any centre which may be ideationally active. When the drainage is reduced in any way it probably makes the active process more intense.

[131] M. A. Maury gives a number: _op. cit._ pp. 126-8.

[132] M. Binet's highly important experiments, which were first published in vol. XVII of the Revue Philosophique (1884), are also given in full in chapter ix of his and Féré's work on 'Animal Magnetism' in the International Scientific Series. Where there is no dot on the paper, nor any other visible mark, the subject's judgment about the 'portrait' would seem to be guided by what he sees happening to the entire sheet.

[133] It is a difficult thing to distinguish in a hypnotic patient between a genuine sensorial hallucination of something suggested and a conception of it merely, coupled with belief that it is there. I have been surprised at the vagueness with which such subjects will often trace upon blank paper the outlines of the pictures which they say they 'see' thereupon. On the other hand, you will hear them say that they find no difference between a real flower which you show them and an imaginary flower which you tell them is beside it. When told that one is imaginary and that they must pick out the real one, they sometimes say the choice is impossible, and sometimes they point to the imaginary flower.

[134] Only the other day, to three hypnotized girls, I failed to double a hallucination with a prism. Of course it may not have been a fully-developed hallucination.

[135] Brain, xi. 441.

[136] Mind, x. 161, 316; and Phantasms of the Living (1886), i. 470-488.

[137] In Mr. Gurney's work, just cited, a very large number of veridical cases are critically discussed.

[138] Mental Evolution in Animals, p. 186.

[139] _Literature._ The best treatment of perception with which I am acquainted is that in Mr. James Sully's book on 'Illusions' in the International Scientific Series. On hallucinations the literature is large. Gurney, Kandinsky (as already cited), and some articles by Kraepelin in the Vierteljahrschrift für Wissenschaftliche Philosophie, vol. v (1881), are the most systematic studies recently made. All works on Insanity treat of them. Dr. W. W. Ireland's works, 'The Blot upon the Brain' (1886) and 'Through the Ivory Gate' (1890) have much information on the subject. Gurney gives pretty complete references to older literature. The most important thing on the subject from the point of view of theory is the article by Mr. Myers on the Demon of Socrates in the Proceedings of the Society for Psychical Research for 1889, p. 522.



CHAPTER XX.

THE PERCEPTION OF SPACE.[140]

THE FEELING OF CRUDE EXTENSITY.


_In the sensations of hearing, touch, sight, and pain we are accustomed to distinguish from among the other elements the element of voluminousness._ We call the reverberations of a thunderstorm more voluminous than the squeaking of a slate-pencil; the entrance into a warm bath gives our skin a more massive feeling than the prick of a pin; a little neuralgic pain, fine as a cobweb, in the face, seems less extensive than the heavy soreness of a boil or the vast discomfort of a colic or a lumbago; and a solitary star looks smaller than the noonday sky. In the sensation of dizziness or subjective motion, which recent investigation has proved to be connected with stimulation of the semi-circular canals of the ear, the spatial character is very prominent. Whether the 'muscular sense' directly yields us knowledge of space is still a matter of litigation among psychologists. Whilst some go so far as to ascribe our entire cognition of extension to its exclusive aid, others deny to it all extensive quality whatever. Under these circumstances we shall do better to adjourn its consideration; admitting, however, that it seems at first sight as if we felt something decidedly more voluminous when we contract our thigh-muscles than when we twitch an eyelid or some small muscle in the face. It seems, moreover, as if this difference lay in the feeling of the thigh-muscles themselves.

In the sensations of smell and taste this element of varying vastness seems less prominent but not altogether absent. Some tastes and smells appear less extensive than complex flavors, like that of roast meat or plum pudding, on the one hand, or heavy odors like musk or tuberose, on the other. The epithet _sharp_ given to the acid class would seem to show that to the popular mind there is something narrow and, as it were, streaky, in the impression they make, other flavors and odors being bigger and rounder.

The sensations derived from the inward organs are also distinctly more or less voluminous. Repletion and emptiness, suffocation, palpitation, headache, are examples of this, and certainly not less spatial is the consciousness we have of our general bodily condition in nausea, fever, heavy drowsiness, and fatigue. Our entire cubic content seems then sensibly manifest to us as such, and feels much larger than any local pulsation, pressure, or discomfort. Skin and retina are, however, the organs in which the space-element plays the most active part. Not only does the maximal vastness yielded by the retina surpass that yielded by any other organ, but the intricacy with which our attention can subdivide this vastness and perceive it to be composed of lesser portions simultaneously coexisting alongside of each other is without a parallel elsewhere.[141] The ear gives a greater vastness than the skin, but is considerably less able to subdivide it.[142]

      *       *       *       *       *

_Now my first thesis is that this element, discernible in each and every sensation, though more developed in some than in others, is the original sensation of space,_ out of which all the exact knowledge about space that we afterwards come to have is woven by processes of discrimination, association, and selection. 'Extensity,' as Mr. James Ward calls it,[143] on this view, becomes an element in each sensation just as intensity is. The latter every one will admit to be a distinguishable though not separable ingredient of the sensible quality. In like manner extensity, being an entirely peculiar kind of feeling indescribable except in terms of itself, and inseparable in actual experience from some sensational quality which it must accompany, can itself receive no other name than that of _sensational element_.

It must now be noted that _the vastness hitherto spoken of is as great in one direction as in another_. Its dimensions are so vague that in it there is no question as yet of surface as opposed to depth; 'volume' being the best short name for the sensation in question. _Sensations of different orders are roughly comparable, inter se, with respect to their volumes._ This shows that the spatial quality in each is identical wherever found, for different qualitative elements, e.g. warmth and odor, are incommensurate. Persons born blind are reported surprised at the largeness with which objects appear to them when their sight is restored. Franz says of his patient cured of cataract: "He saw everything much larger than he had supposed from the idea obtained by his sense of touch. Moving, and especially living, objects appeared very large."[144] Loud sounds have a certain enormousness of feeling. It is impossible to conceive of the explosion of a cannon as filling a small space. In general, sounds seem to occupy all the room between us and their source; and in the case of certain ones, the cricket's song, the whistling of the wind, the roaring of the surf, or a distant railway train, to have no definite starting point.

In the sphere of vision we have facts of the same order. 'Glowing' bodies, as Hering says, give us a perception "which seems _roomy_ (_raumhaft_) in comparison with that of strictly surface color. A glowing iron looks luminous through and through, and so does a flame."[145] A luminous fog, a band of sunshine, affect us in the same way. As Hering urges:

"We must distinguish _roomy_ from superficial, as well as distinctly
from indistinctly bounded, sensations. The dark which with closed eyes
one sees before one is, for example, a roomy sensation. We do not
see a black surface like a wall in front of us, but a space filled
with darkness, and even when we succeed in seeing this darkness as
terminated by a black wall there still remains in front of this wall
the dark space. The same thing happens when we find ourselves with
open eyes in an absolutely dark room. This sensation of darkness
is also vaguely bounded. An example of a distinctly bounded roomy
sensation is that of a clear and colored fluid seen in a glass; the
yellow of the wine is seen not only on the bounding surface of the
glass; the yellow sensation fills the whole interior of the glass. By
day the so-called empty space between us and objects seen appears very
different from what it is by night. The increasing darkness settles
not only upon the things but also _between_ us and the things, so as
at last to cover them completely and fill the space alone. If I look
into a dark box I find it _filled_ with darkness, and this is seen
not merely as the dark-colored sides or walls of the box. A shady
corner in an otherwise well-lighted room is full of a darkness which
is not only _on_ the walls and floor but _between_ them in the space
they include. Every sensation is there where I experience it, and if
I have it at once at every point of a certain roomy space, it is then
a voluminous sensation. A cube of transparent green glass gives us a
spatial sensation; an opaque cube painted green, on the contrary, only
sensations of surface."[146]

_There are certain quasi-motor sensations in the head_ when we change the direction of the attention, which equally seem to involve three dimensions. If with closed eyes we think of the top of the house and then of the cellar, of the distance in front of us and then of that behind us, of space far to the right and then far to the left, we have something far stronger than an idea,--an actual feeling, namely, as if something in the head moved into another direction. Fechner was, I believe, the first to publish any remarks on these feelings. He writes as follows:

"When we transfer the attention from objects of one sense to those
of another we have an indescribable feeling (though at the same time
one perfectly determinate and reproducible at pleasure) of altered
direction, or differently localized tension (_Spannung_). We feel
a strain forward in the eyes, one directed sideways in the ears,
increasing with the degree of our attention, and changing according as
we look at an object carefully, or listen to something attentively;
wherefore we speak of _straining the attention_. The difference is
most plainly felt when the attention vibrates rapidly between eye
and ear. This feeling localizes itself with most decided difference
in regard to the various sense-organs according as we wish to
discriminate a thing delicately by touch, taste, or smell.
"But now I have, when I try to vividly recall a picture of memory
or fancy, a feeling perfectly analogous to that which I experience
when I seek to grasp a thing keenly by eye or ear; and this analogous
feeling is very differently localized. While in sharpest possible
attention to real objects (as well as to after-images) the strain is
plainly forwards, and, when the attention changes from one sense to
another, only alters its direction between the sense-organs, leaving
the rest of the head free from strain, the case is different in memory
or fancy; for here the feeling withdraws entirely from the external
sense-organs, and seems rather to take refuge in that part of the
head which the brain fills. If I wish, for example, to recall a place
or person, it will arise before me with vividness, not according as
I strain my attention forwards, but rather in proportion as I, so to
speak, retract it backwards."[147]

It appears probable that the feelings which Fechner describes are in part constituted by imaginary semi-circular canal sensations.[148] These undoubtedly convey the most delicate perception of change in direction; and when, as here, the changes are not perceived as taking place in the external world, they occupy a vague internal space located within the head.[149]

In the skin itself there is a vague form of projection into the third dimension to which Hering has called attention.

"Heat is not felt only against the cutaneous surface, but when
communicated through the air may appear extending more or less out
from the surface into the third dimension of surrounding space....
We can determine in the dark the place of a radiant body by moving
the hand to and fro, and attending to the fluctuation of our feeling
of warmth. The feeling itself, however, is not projected fully into
the spot at which we localize the hot body, but always remains in the
neighborhood of the hand."

The interior of one's mouth-cavity feels larger when explored by the tongue than when looked at. The crater of a newly-extracted tooth, and the movements of a loose tooth in its socket, feel quite monstrous. A midge buzzing against the drum of the ear will often seem as big as a butterfly. The spatial sensibility of the tympanic membrane has hitherto been very little studied, though the subject will well repay much trouble. If we approach it by introducing into the outer ear some small object like the tip of a rolled-up tissue-paper lamplighter, we are surprised at the large radiating sensation which its presence gives us, and at the sense of clearness and openness which comes when it is removed. It is immaterial to inquire whether the far-reaching sensation here be due to actual irradiation upon distant nerves or not. We are considering now, not the objective causes of the spatial feeling, but its subjective varieties, and the experiment shows that the same object gives more of it to the inner than to the outer cuticle of the ear. The pressure of the air in the tympanic cavity upon the membrane gives an astonishingly large sensation. We can increase the pressure by holding our nostrils and closing our mouth and forcing air through our Eustachian tubes by an expiratory effort; and we can diminish it by either inspiring or swallowing under the same conditions of closed mouth and nose. In either case we get a large round tridimensional sensation inside of the head, which seems as if it must come from the affection of an organ much larger than the tympanic membrane, whose surface hardly exceeds that of one's little-finger-nail.

The tympanic membrane is furthermore able to render sensible differences in the pressure of the external atmosphere, too slight to be felt either as noise or in this more violent way. If the reader will sit with closed eyes and let a friend approximate some solid object, like a large book, noiselessly to his face, he will immediately become aware of the object's presence and position--likewise of its departure. A friend of the writer, making the experiment for the first time, discriminated unhesitatingly between the three degrees of solidity of a board, a lattice-frame, and a sieve, held close to his ear. Now as this sensation is never used by ordinary persons as a means of perception, we may fairly assume that its felt quality, in those whose attention is called to it for the first time, belongs to it _quâ_ sensation, and owes nothing to educational suggestions. But this felt quality is most distinctly and unmistakably one of vague spatial vastness in three dimensions--quite as much so as is the felt quality of the retinal sensation when we lie on our back and fill the entire field of vision with the empty blue sky. When an object is brought near the ear we immediately feel shut in, contracted; when the object is removed, we suddenly feel as if a transparency, clearness, openness, had been made outside of us. And the feeling will, by any one who will take the pains to observe it, be acknowledged to involve the third dimension in a vague, unmeasured state.[150]

The reader will have noticed, in this enumeration of facts, that _voluminousness of the feeling seems to bear very little relation to the size of the organ that yields it_. The ear and eye are comparatively minute organs, yet they give us feelings of great volume. The same lack of exact proportion between size of feeling and size of organ affected obtains within the limits of particular sensory organs. An object appears smaller on the lateral portions of the retina than it does on the fovea, as may be easily verified by holding the two forefingers parallel and a couple of inches apart, and transferring the gaze of one eye from one to the other. Then the finger not directly looked at will appear to shrink, and this whatever be the direction of the fingers. On the tongue a crumb, or the calibre of a small tube, appears larger than between the fingers. If two points kept equidistant (blunted compass- or scissors-points, for example) be drawn across the skin so as really to describe a pair of parallel lines, the lines will appear farther apart in some spots than in others. If, for example, we draw them horizontally across the face, so that the mouth falls between them, the person experimented upon will feel as if they began to diverge near the mouth and to include it in a well-marked ellipse. In like manner, if we keep the compass-points one or two centimetres apart, and draw them down the forearm over the wrist and palm, finally drawing one along one finger, the other along its neighbor, the appearance will be that of a single line, soon breaking into two, which become more widely separated below the wrist, to contract again in the palm, and finally diverge rapidly again towards the finger-tips. The dotted lines in Figs. 51 and 52 represent the true path of the compass-points; the full lines their apparent path.

[Illustration: FIG. 51 (after Weber).]

The same length of skin, moreover, will convey a more extensive sensation according to the manner of stimulation. If the edge of a card be pressed against the skin, the distance between its extremities will seem shorter than that between two compass-tips touching the same terminal points.[151]

[Illustration: FIG. 52 (after Weber).]

In the eye, intensity of nerve-stimulation seems to increase the _volume_ of the feeling as well as its brilliancy. If we raise and lower the gas alternately, the whole room and all the objects in it seem alternately to enlarge and contract. If we cover half a page of small print with a gray glass, the print seen through the glass appears decidedly smaller than that seen outside of it, and the darker the glass the greater the difference. When a circumscribed opacity in front of the retina keeps off part of the light from the portion which it covers, objects projected on that portion may seem but half as large as when their image falls outside of it.[152] The inverse effect seems produced by certain drugs and anæsthetics. Morphine, atropine, daturine, and cold blunt the sensibility of the skin, so that distances upon it seem less. Haschish produces strange perversions of the general sensibility. Under its influence one's body may seem either enormously enlarged or strangely contracted. Sometimes a single member will alter its proportion to the rest; or one's back, for instance, will appear entirely absent, as if one were hollow behind. Objects comparatively near will recede to a vast distance, a short street assume to the eye an immeasurable perspective. Ether and chloroform occasionally produce not wholly dissimilar results. Panum, the German physiologist, relates that when, as a boy, he was etherized for neuralgia, the objects in the room grew extremely small and distant, before his field of vision darkened over and the roaring in his ears began. He also mentions that a friend of his in church, struggling in vain to keep awake, saw the preacher grow smaller and smaller and more and more distant. I myself on one occasion observed the same recession of objects during the beginning of chloroformization. In various cerebral diseases we find analogous disturbances.

_Can we assign the physiological conditions which make the elementary sensible largeness of one sensation vary so much from that of another?_ Only imperfectly. One factor in the result undoubtedly is the number of nerve-terminations simultaneously excited by the outward agent that awakens the sensation. When many skin-nerves are warmed, or much retinal surface illuminated, our feeling is larger than when a lesser nervous surface is excited. The single sensation yielded by two compass-points, although it seems simple, is yet felt to be much bigger and blunter than that yielded by one. The touch of a single point may always be recognized by its quality of sharpness. This page looks much smaller to the reader if he closes one eye than if both eyes are open. So does the moon, which latter fact shows that the phenomenon has nothing to do with parallax. The celebrated boy couched for the cataract by Chesselden thought, after his first eye was operated, "all things he saw extremely large," but being couched of his second eye, said "that objects at first appeared large to this eye, but not so large as they did at first to the other; and looking upon the same object with both eyes, he thought it looked about twice as large as with the first couched eye only, but not double, that we can anyways discover."

The greater extensiveness that the feeling of certain parts of the same surface has over other parts, and that one order of surface has over another (retina over skin, for example), may also to a certain extent be explained by the operation of the same factor. It is an anatomical fact that the most spatially sensitive surfaces (retina, tongue, finger-tips, etc.) are supplied by nerve-trunks of unusual thickness, which must supply to every unit of surface-area an unusually large number of terminal fibres. But the variations of felt extension obey probably only a very rough law of numerical proportion to the number of fibres. A sound is not twice as voluminous to two ears as to one; and the above-cited variations of feeling, when the same surface is excited under different conditions, show that the feeling is a resultant of several factors of which the anatomical one is only the principal. Many ingenious hypotheses have been brought forward to assign the co-operating factors where different conditions give conflicting amounts of felt space. Later we shall analyze some of these cases in detail, but it must be confessed here in advance that many of them resist analysis altogether.[153]


THE PERCEPTION OF SPATIAL ORDER.


So far, all we have established or sought to establish is the existence of the vague form or _quale_ of spatiality as an inseparable element bound up with the other peculiarities of each and every one of our sensations. The numerous examples we have adduced of the variations of this extensive element have only been meant to make clear its strictly sensational character. In very few of them will the reader have been able to explain the variation by an added intellectual element, such as the suggestion of a recollected experience. In almost all it has seemed to be the immediate psychic effect of a peculiar sort of nerve-process excited; and all the nerve-processes in question agree in yielding what space they do yield, to the mind, in the shape of a simple total vastness, in which, _primitively_ at least, no _order of parts_ or of _subdivisions_ reigns.

Let no one be surprised at this notion of a space without order. There may be a space without order just as there may be an order without space.[154] And the primitive perceptions of space are certainly of an unordered kind. The order which the spaces first perceived potentially include must, before being distinctly apprehended by the mind, be woven into those spaces by a rather complicated set of intellectual acts. The primordial largenesses which the sensations yield must be _measured and subdivided_ by consciousness, and _added_ together, before they can form by their synthesis what we know as the real Space of the objective world. In these operations, imagination, association, attention, and selection play a decisive part; and although they nowhere add any new material to the space-data of sense, they so shuffle and manipulate these data and hide present ones behind imagined ones that it is no wonder if some authors have gone so far as to think that the sense-data have no spatial worth at all, and that the intellect, since it makes the subdivisions, also gives the spatial quality to them out of resources of its own.

      *       *       *       *       *

As for ourselves, having found that all our sensations (however as yet unconnected and undiscriminated) are of extensive objects, _our next problem, is: How do we_ ARRANGE _these at first chaotically given spaces into the one regular and orderly 'world of space' which we now know?_

To begin with, there is no reason to suppose that the several sense-spaces of which a sentient creature may become conscious, each filled with its own peculiar content, should tend, simply _because they are many_, to enter into any definite spatial intercourse with each other, or lie in any particular order of positions. Even in ourselves we can recognize this. Different feelings may coexist in us without assuming any particular spatial order. The sound of the brook near which I write, the odor of the cedars, the comfort with which my breakfast has filled me, and my interest in this paragraph, all lie distinct in my consciousness, but in no sense outside or alongside of each other. Their spaces are interfused and at most fill the same vaguely objective world. Even where the qualities are far less disparate, we may have something similar. If we take our subjective and corporeal sensations alone, there are moments when, as we lie or sit motionless, we find it very difficult to feel distinctly the length of our back or the direction of our feet from our shoulders. By a strong effort we can succeed in dispersing our attention impartially over our whole person, and then we feel the real shape of our body in a sort of unitary way. But in general a few parts are strongly emphasized to consciousness and the rest sink out of notice; and it is then remarkable how vague and ambiguous our perception of their relative order of location is. Obviously, for the orderly arrangement of a multitude of sense-spaces in consciousness, something more than their mere separate existence is required. What is this further condition?

_If a number of sensible extents are to be perceived alongside of each other and in definite order they must appear as parts in a vaster sensible extent which can enter the mind simply and all at once_. I think it will be seen that the difficulty of estimating correctly the form of one's body by pure feeling arises from the fact that it is very hard to feel its totality as a unit at all. The trouble is similar to that of thinking forwards and backwards simultaneously. When conscious of our head we tend to grow unconscious of our feet, and there enters thus an element of time-succession into our perception of ourselves which transforms the latter from an act of intuition to one of construction. This element of constructiveness is present in a still higher degree, and carries with it the same consequences, when we deal with objective spaces too great to be grasped by a single look. The relative positions of the shops in a town, separated by many tortuous streets, have to be thus constructed from data apprehended in succession, and the result is a greater or less degree of vagueness.

That a sensation _be discriminated as a part_ from out of a larger enveloping space is then the _conditio sine quâ non_ of its being apprehended in a definite spatial order. The problem of ordering our feelings in space is then, in the first instance, a problem of discrimination, but not of discrimination pure and simple; for then not only coexistent sights but coexistent sounds would necessarily assume such order, which they notoriously do not. Whatever is discriminated will appear as a small space within a larger space, it is true, but this is but the very rudiment of order. For the location of it within that space to become precise, other conditions still must supervene; and the best way to study what they are will be to pause for a little and _analyze what the expression 'spatial order' means_.

      *       *       *       *       *

Spatial order is an abstract term. The concrete perceptions which it covers are figures, directions, positions, magnitudes, and distances. To single out any one of these things from a total vastness is partially to introduce order into the vastness. To subdivide the vastness into a multitude of these things is to apprehend it in a completely orderly way. Now what are these things severally? To begin with, no one can for an instant hesitate to say that some of them are qualities of sensation, just as the total vastness is in which they lie. Take figure: a square, a circle, and a triangle appear in the first instance to the eye simply as three different kinds of impressions, each so peculiar that we should recognize it if it were to return. When Nunnely's patient had his cataracts removed, and a cube and a sphere were presented to his notice, he could at once perceive a difference in their shapes; and though he could not say which was the cube and which the sphere, he saw they were not of the same figure. So of lines: if we can notice lines at all in our field of vision, it is inconceivable that a vertical one should not affect us differently from an horizontal one, and should not be recognized as affecting us similarly when presented again, although we might not yet know the name 'vertical,' or any of its connotations, beyond this peculiar affection of our sensibility. So of angles: an obtuse one affects our feeling immediately in a different way from an acute one. Distance-apart, too, is a simple sensation--the sensation of a line joining the two distant points: lengthen the line, you alter the feeling and with it the distance felt.


_Space-relations._


But with distance and direction we pass to the category of space-_relations_, and are immediately confronted by an opinion which makes of all relations something _toto cœlo_ different from all facts of feeling or imagination whatsoever. A relation, for the Platonizing school in psychology, is an energy of pure thought, and, as such, is quite incommensurable with the data of sensibility between which it may be perceived to obtain.

We may consequently imagine a disciple of this school to say to us at this point: "Suppose you _have_ made a separate specific sensation of each line and each angle, what boots it? You have still the order of directions and of distances to account for; you have still the relative magnitudes of all these felt figures to state; you have their respective positions to define before you can be said to have brought order into your space. And not one of these determinations can be effected except through an act of relating thought, so that your attempt to give an account of space in terms of pure sensibility breaks down almost at the very outset. _Position_, for example, can never be a sensation, for it has nothing intrinsic about it; it can only obtain _between_ a spot, line, or other figure and _extraneous co-ordinates_, and can never be an element of the sensible datum, the line or the spot, in itself. Let us then confess that Thought alone can unlock the riddle of space, and that Thought is an adorable but unfathomable mystery."

Such a method of dealing with the problem has the merit of shortness. Let us, however, be in no such hurry, but see whether we cannot get a little deeper by patiently considering what these space-relations are.

'Relation' is a very slippery word. It has so many different concrete meanings that the use of it as an abstract universal may easily introduce bewilderment into our thought. We must therefore be careful to avoid ambiguity by making sure, wherever we have to employ it, what its precise meaning is in that particular sphere of application. At present we have to do with space-relations, and no others. Most 'relations' are feelings of an entirely different order from the terms they relate. The relation of similarity, e.g., may equally obtain between jasmine and tuberose, or between Mr. Browning's verses and Mr. Story's; it is itself neither odorous nor poetical, and those may well be pardoned who have denied to it all sensational content whatever. But just as, in the field of quantity, the relation between two numbers is another number, so _in the field of space the relations are facts of the same order with the facts they relate. If these latter be patches in the circle of vision, the former are certain other patches between them._ When we speak of the relation of direction of two points toward each other, we mean simply the sensation of the line that joins the two points together. _The line is the relation;_ feel it and you feel the relation, see it and you see the relation; nor can you in any conceivable way think the latter except by imagining the former (however vaguely), or describe or indicate the one except by pointing to the other. And the moment you have imagined the line, the relation stands before you in all its completeness, with nothing further to be done. Just so the relation of _direction_ between two lines is identical with the peculiar sensation of shape of the space enclosed between them. This is commonly called an angular relation.

If these relations are sensations, no less so are the relations of position. _The relation of position between the top and bottom points of a vertical line is that line,_ and nothing else. The relations of position between a point and a horizontal line below it are potentially numerous. There is one more important than the rest, called its distance. This is the sensation, ideal or actual, of a perpendicular drawn from the point to the line.[155] Two lines, one from each extremity of the horizontal to the point, give us a peculiar sensation of triangularity. This feeling may be said to constitute the _locus_ of all the relations of position of the elements in question. _Rightness and leftness, upness and downness, are again pure sensations_ differing specifically from each other, and generically from everything else. Like all sensations, they can only be indicated, not described. If we take a cube and label one side _top_, another _bottom_, a third _front_, and a fourth _back_, there remains no form of words by which we can describe to another person which of the remaining sides is _right_ and which _left_. We can only point and say _here_ is right and _there_ is left, just as we should say _this_ is red and _that_ blue. Of two points seen beside each other at all, one is always affected by one of these feelings, and the other by the opposite; the same is true of the extremities of any line.[156]

Thus it appears indubitable that all space-relations except those of magnitude are nothing more or less than pure sensational objects. But _magnitude_ appears to outstep this narrow sphere. We have relations of muchness and littleness between times, numbers, intensities, and qualities, as well as spaces. It is impossible, then, that such relations should form a particular kind of simply spatial feeling. This we must admit: the relation of quantity is generic and occurs in many categories of consciousness, whilst the other relations we have considered are specific and occur in space alone. When our attention passes from a shorter line to a longer, from a smaller spot to a larger, from a feebler light to a stronger, from a paler blue to a richer, from a march tune to a galop, the transition is accompanied in the synthetic field of consciousness by a peculiar feeling of difference which is what we call the sensation of _more_,--more length, more expanse, more light, more blue, more motion. This transitional sensation of _more_ must be identical with itself under all these different accompaniments, or we should not give it the same name in every case. We get it when we pass from a short vertical line to a long horizontal one, from a small square to a large circle, as well as when we pass between those figures whose shapes are congruous. But when the shapes are congruous our consciousness of the relation is a good deal more distinct, and it is most distinct of all when, in the exercise of our analytic attention, we notice, first, a _part_, and then the _whole_, of a _single_ line or shape. Then the _more_ of the whole actually sticks out, as a separate piece of space, and is so envisaged. The same exact sensation of it is given when we are able to superpose one line or figure on another. This indispensable condition of exact measurement of the _more_ has led some to think that the feeling itself arose in every case from original experiences of superposition. This is probably not an absolutely true opinion, but for our present purpose that is immaterial. So far as the subdivisions of a sense-space are to be _measured_ exactly against each other, objective forms occupying one subdivision must directly or indirectly be superposed upon the other, and the mind must get the immediate feeling of an outstanding _plus_. And even where we only feel one subdivision to be vaguely larger or less, the mind must pass rapidly between it and the other subdivision, and receive the immediate sensible shock of the _more_.

      *       *       *       *       *

_We seem thus to have accounted for all space-relations, and made them clear to our understanding. They are nothing but sensations of particular lines, particular angles, particular forms of transition, or_ (in the case of a _distinct more) of particular outstanding portions of space after two figures have been superposed._ These relation-sensations may actually be produced as such, as when a geometer draws new lines across a figure with his pencil to demonstrate the relations of its parts, or they may be ideal representations of lines, not really drawn. But in either case their entrance into the mind is equivalent to a more detailed subdivision, cognizance, and measurement of the space considered. _The bringing of subdivisions to consciousness constitutes, then, the entire process by which we pass from our first vague feeling of a total vastness to a cognition of the vastness in detail._ The more numerous the subdivisions are, the more elaborate and perfect the cognition becomes. But inasmuch as all the subdivisions are themselves sensations, and even the feeling of 'more' or 'less' is, where not itself a figure, at least a sensation of transition between two sensations of figure, it follows, for aught we can as yet see to the contrary, that _all spatial knowledge is sensational at bottom_, and that, as the sensations lie together in the unity of consciousness, no new material element whatever comes to them from a supra-sensible source.[157]

_The bringing of subdivisions to consciousness! This, then, is our next topic._ They may be brought to consciousness under three aspects in respect of their _locality_, in respect of their _size_, in respect of their _shape_.


_The Meaning of Localization._


_Confining ourselves to the problem of locality_ for the present, let us begin with the simple case of a sensitive surface, only two points of which receive stimulation from without. How, first, are these two points felt as alongside of each other with an interval of space between them? We must be conscious of two things for this: of the duality of the excited points, and of the extensiveness of the unexcited interval. The duality alone, although a necessary, is not a sufficient condition of the spatial separation. We may, for instance, discern two sounds in the same place, sweet and sour in the same lemonade, warm and cold, round and pointed contact in the same place on the skin, etc.[158] In all discrimination the recognition of the duality of two feelings by the mind is the easier the more strongly the feelings are contrasted in quality. If our two excited points awaken identical qualities of sensation, they must, perforce, appear to the mind as one; and, not distinguished at all, they are, _a fortiori_, not localized apart. Spots four centimetres distant on the back have no qualitative contrast at all, and fuse into a single sensation. Points less than three thousandths of a millimetre apart awaken on the retina sensations so contrasted that we apprehend them immediately as two. Now these unlikenesses which arise so slowly when we pass from one point to another in the back, so much faster on the tongue and finger-tips, but with such inconceivable rapidity on the retina, what are they? Can we discover anything about their intrinsic nature?

The most natural and immediate answer to make is that they are unlikeness of _place_ pure and simple. In the words of a German physiologist,[159] to whom psychophysics owes much:

"The sensations are from the outset (_von vornherein_) localized....
Every sensation as such is from the very beginning affected with the
spatial quality, so that this quality is nothing like an external
attribute coming to the sensation from a higher faculty, but must be
regarded as something immanently residing in the sensation itself."

And yet the moment we reflect on this answer an insuperable logical difficulty seems to present itself. No single _quale_ of sensation can, by itself, amount to a consciousness of _position_. Suppose no feeling but that of a single point ever to be awakened. Could that possibly be the feeling of any special _whereness_ or _thereness_? Certainly not. _Only when a second point is felt to arise can the first one acquire a determination of up, down, right or left, and these determinations are all relative to that second point._ Each point, so far as it is _placed, is_ then only by virtue of what it _is not,_ namely, by virtue of another point. This is as much as to say that position has nothing _intrinsic_ about it; and that, although a feeling of absolute bigness may, _a feeling of place cannot, possibly form an immanent element in any single isolated sensation._ The very writer we have quoted has given heed to this objection, for he continues (p. 335) by saying that the sensations thus originally localized "are only so _in themselves_, but not in the representation of consciousness, which is not yet present.... They are, in the first instance, devoid of all mutual relations with each other." But such a localization of the sensation 'in itself' would seem to mean nothing more than the susceptibility or _potentiality_ of being distinctly localized when the time came and other conditions became fulfilled. Can we now discover anything about such susceptibility in itself before it has borne its ulterior fruits in the developed consciousness?


_'Local Signs.'_


To begin with, every sensation of the skin and every visceral sensation seems to derive from its topographic seat a peculiar shade of feeling, which it would not have in another place. And this feeling _per se_ seems quite another thing from the perception of the place. Says Wundt[160]:

"If with the finger we touch first the cheek and then the palm,
exerting each time precisely the same pressure, the sensation shows
notwithstanding a distinctly marked difference in the two cases.
Similarly, when we compare the palm with the back of the hand, the
nape of the neck with its anterior surface, the breast with the
back; in short, any two distant parts of the skin with each other.
And moreover, we easily remark, by attentively observing, that spots
even tolerably close together differ in respect of the quality of
their feeling. If we pass from one point of our cutaneous surface to
another, we find a perfectly gradual and continuous alteration in
our feeling, notwithstanding the objective nature of the contact has
remained the same. Even the sensations of corresponding points on
opposite sides of the body, though similar, are not identical. If,
for instance, we touch first the back of one hand and then of the
other, we remark a qualitative unlikeness of sensation. It must not
be thought that such differences are mere matters of imagination, and
that we take the sensations to be different because we represent each
of them to ourselves as occupying a different place. With sufficient
sharpening of the attention, we may, confining ourselves to the
quality of the feelings alone, entirely abstract from their locality,
and yet notice the differences quite as markedly."

Whether these local contrasts shade into each other with absolutely continuous gradations, we cannot say. But we know (continues Wundt) that

"they change, when we pass from one point of the skin to its neighbor,
with very different degrees of rapidity. On delicately-feeling parts,
used principally for touching, such as the finger-tips, the difference
of sensation between two closely approximate points is already
strongly pronounced; whilst in parts of lesser delicacy, as the arm,
the back, the legs, the disparities of sensation are observable only
between distant spots."

The internal organs, too, have their specific _qualia_ of sensation. An inflammation of the kidney is different from one of the liver; pains in joints and muscular insertions are distinguished. Pain in the dental nerves is wholly unlike the pain of a burn. But very important and curious similarities prevail throughout these differences. Internal pains, whose seat we cannot see, and have no means of knowing unless the character of the pain itself reveal it, are felt _where_ they belong. Diseases of the stomach, kidney, liver, rectum, prostate, etc., of the bones, of the brain and its membranes, are referred to their proper position. Nerve-pains describe the length of the nerve. Such localizations as those of vertical, frontal, or occipital headache of intracranial origin force us to conclude that parts which are neighbors, whether inner or outer, may possess by mere virtue of that fact a common peculiarity of feeling, a respect in which their sensations agree, and which serves as a token of their proximity. These _local_ colorings are, moreover, so strong that we cognize them as the same, throughout all contrasts of sensible quality in the accompanying perception. Cold and heat are wide as the poles asunder; yet if both fall on the cheek, there mixes with them something that makes them in _that respect_ identical; just as, contrariwise, despite the identity of cold with itself wherever found, when we get it first on the palm and then on the cheek, some difference comes, which keeps the two experiences for ever asunder.[161]

And now let us revert to the query propounded a moment since: _Can these differences of mere quality in feeling, varying according to locality yet having each sensibly and intrinsically and by itself nothing to do with position, constitute the 'susceptibilities' we mentioned, the conditions of being perceived in position, of the localities to which they belong?_ The numbers on a row of houses, the initial letters of a set of words, have no intrinsic kinship with points of space, and yet they are the conditions of our knowledge of where any house is in the row, or any word in the dictionary. Can the modifications of feeling in question be tags or labels of this kind which in no wise originally reveal the position of the spot to which they are attached, but guide us to it by what Berkeley would call a 'customary tie'? Many authors have unhesitatingly replied in the affirmative; Lotze, who in his Medizinische Psychologie[162] first described the sensations in this way, designating them, thus conceived, as _local-signs_. This term has obtained wide currency in Germany, and _in speaking of the_ 'LOCAL-SIGN THEORY' _hereafter, I shall always mean the theory which denies that there can be in a sensation any element of actual locality, of inherent spatial order,_ any tone as it were which cries to us immediately and without further ado, 'I am _here_,' or 'I am _there_.'

If, as may well be the case, we by this time find ourselves tempted to accept the Local-sign theory in a general way, we have to clear up several farther matters. If a sign is to lead us to _the thing_ it means, we must have some other source of knowledge of that thing. Either the thing has been given in a previous experience of which the sign also formed part--they are _associated_; or it is what Reid calls a 'natural' sign, that is, a feeling which, the first time it enters the mind, evokes from the native powers thereof a cognition of the thing that hitherto had lain dormant. In both cases, however, the sign is one thing, and the thing another. In the instance that now concerns us, _the sign is a quality of feeling and the thing is a position_. Now we have seen that the position of a point is not only revealed, but created, by the existence of other points to which it stands in determinate _relations. If the sign can by any machinery which it sets in motion evoke a consciousness either of the other points, or of the relations, or of both, it would seem to fulfil its function, and reveal to us the position we seek._

But such a machinery is already familiar to us. It is neither more nor less than the law of habit in the nervous system. When any point of the sensitive surface has been frequently excited simultaneously with, or immediately before or after, other points, and afterwards comes to be excited alone, there will be a tendency for its perceptive nerve-centre to irradiate into the nerve-centres of the other points. Subjectively considered, this is the same as if we said that _the peculiar feeling of the first point_ SUGGESTS _the feeling of the entire region with whose stimulation its own excitement has been habitually_ ASSOCIATED.

Take the case of the stomach. When the epigastrium is heavily pressed, when certain muscles contract, etc., the stomach is squeezed, and its peculiar local sign awakes in consciousness simultaneously with the local signs of the other squeezed parts. There is also a sensation of total vastness aroused by the combined irritation, and _somewhere_ in this the stomach-feeling seems to lie. Suppose that later a pain arises in the stomach from some non-mechanical cause. It will be tinged by the gastric local sign, and the nerve-centre supporting this latter feeling will excite the centre supporting the dermal and muscular feelings habitually associated with it when the excitement was mechanical. From the combination the same peculiar vastness will again arise. In a word, 'something' in the stomach-sensation 'reminds' us of a total space, of which the diaphragmatic and epigastric sensations also form a part, or, to express it more briefly still, suggests the neighborhood of these latter organs.[163]

Revert to the case of two excited points on a surface with an unexcited space between them. The general result of previous experience has been that when either point was impressed by an outward object, the same object also touched the immediately neighboring parts. Each point, together with its local sign, is thus associated with a circle of surrounding points, the association fading in strength as the circle grows larger. Each will revive its own circle; but when both are excited together, the strongest revival will be that due to the _combined_ irradiation. Now the tract _joining the two excited points_ is the only part common to the two circles. And the feelings of this whole tract will therefore awaken with considerable vividness in the imagination when its extremities are touched by an outward irritant. The mind receives with the impression of the two distinct points the vague idea of a line. The twoness of the points comes from the contrast of their local signs: the line comes from the associations into which experience has wrought these latter. If no ideal line arises we have duality without sense of interval; if the line be excited actually rather than ideally, we have the interval given with its ends, in the form of a single extended object felt. E. H. Weber, in the famous article in which he laid the foundations of all our accurate knowledge of these subjects, _laid it down as the logical requisite for the perception of two separated points, that the mind should, along with its consciousness of them, become aware of an unexcited interval as such. I have only tried to show how the known laws of experience may cause this requisite to be fulfilled._ Of course, if the local signs of the entire region offer but little qualitative contrast _inter se_, the line suggested will be but dimly defined or discriminated in length or direction from other possible lines in its neighborhood. This is what happens in the back, where consciousness can sunder two spots, whilst only vaguely apprehending their distance and direction apart.

The relation of position of the two points _is_ the suggested interval or line. Turn now to the simplest case, that of _a single excited spot. How can it suggest its position?_ Not by recalling any particular line unless experience have constantly been in the habit of marking or tracing some one line from it towards some one neighboring point. Now on the back, belly, viscera, etc., no such tracing habitually occurs. The consequence is that the only suggestion is that of the whole neighboring circle; i.e., _the spot simply recalls the general region in which it happens to lie._ By a process of successive construction, it is quite true that we can also get the feeling of distance between the spot and some other particular spot. Attention, by reinforcing the local sign of one part of the circle, can awaken a new circle round this part, and so _de proche en proche_ we may slide our feeling down from our cheek, say, to our foot. But when we first touched our cheek we had no consciousness of the foot at all.[164] In the extremities, the lips, the tongue and other mobile parts, the case is different. We there have an instinctive tendency, when a part of lesser discriminative sensibility is touched, to move the member so that the touching object glides along it to the place where sensibility is greatest. If a body touches our hand we move the hand over it till the finger-tips are able to explore it. If the sole of our foot touches anything we bring it towards the toes, and so forth. There thus arise lines of habitual passage from all points of a member to its sensitive tip. These are the lines most readily recalled when any point is touched, and their recall is identical with the consciousness of the distance of the touched point from the 'tip.' I think anyone must be aware when he touches a point of his hand or wrist that it is the relation to the finger-tips of which he is usually most conscious. Points on the forearm suggest either the finger-tips or the elbow (the latter being a spot of greater sensibility[165]). In the foot it is the toes, and so on. A point can only be cognized in its relations to the entire body at once by awakening a _visual_ image of the whole body. Such awakening is even more obviously than the previously considered cases a matter of pure association.

      *       *       *       *       *

_This leads us to the eye._ On the retina the fovea and the yellow spot about it form a focus of exquisite sensibility, towards which every impression falling on an outlying portion of the field is moved by an instinctive action of the muscles of the eyeball. Few persons, until their attention is called to the fact, are aware how almost impossible it is to keep a conspicuous visible object in the margin of the field of view. The moment volition is relaxed we find that without our knowing it our eyes have turned so as to bring it to the centre. This is why most persons are unable to keep the eyes steadily converged upon a point in space with nothing in it. The objects against the walls of the room invincibly attract the foveæ to themselves. If we contemplate a blank wall or sheet of paper, we always observe in a moment that we are directly looking at some speck upon it which, unnoticed at first, ended by 'catching our eye.' Thus _whenever an image falling on the point P of the retina excites attention, it more habitually moves from that point towards the fovea than in any one other direction._ The line traced thus by the image is not always a straight line. When the direction of the point from the fovea is neither vertical nor horizontal but oblique, the line traced is often a curve, with its concavity directed upwards if the direction is upwards, downwards if the direction is downwards. This may be verified by anyone who will take the trouble to make a simple experiment with a luminous body like a candle-flame in a dark enclosure, or a star. Gazing first at some point remote from the source of light, let the eye be suddenly turned full upon the latter. The luminous image will necessarily fall in succession upon a continuous series of points, reaching from the one first affected to the fovea. But by virtue of the slowness with which retinal excitements die away, the entire series of points will for an instant be visible as an after-image, displaying the above peculiarity of form according to its situation.[166] These radiating lines are neither regular nor invariable in the same person, nor, probably, equally curved in different individuals. We are incessantly drawing them between the fovea and every point of the field of view. Objects remain in their peripheral indistinctness only so long as they are unnoticed. The moment we attend to them they grow distinct through one of these motions--which leads to the idea prevalent among uninstructed persons that we see distinctly all parts of the field of view at once. _The result of this incessant tracing of radii is that whenever a local sign P is awakened by a spot of light falling upon it, it recalls forthwith, even though the eyeball be unmoved, the local signs of all the other points which lie between P and the fovea._ It recalls them in imaginary form, just as the normal reflex movement would recall them in vivid form; and with their recall is given a consciousness more or less faint of the whole line on which they lie. In other words, no ray of light can fall on any retinal spot without the local sign of that spot revealing to us, by recalling the line of its most habitual associates, its direction and distance from the centre of the field. The fovea acts thus as the origin of a system of polar co-ordinates, in relation to which each and every retinal point has through an incessantly-repeated process of association its distance and direction determined. Were _P_ alone illumined and all the rest of the field dark we should still, even with motionless eyes, know whether _P_ lay high or low, right or left, through the _ideal streak_, different from all other streaks, which _P_ alone has the power of awakening.[167]

And with this we can close the first great division of our subject. We have shown that, within the range of every sense, experience takes _ab initio_ the spatial form. We have also shown that in the cases of the retina and skin every sensible total may be subdivided by discriminative attention into sensible parts, which are also spaces, and into relations between the parts, these being sensible spaces too. Furthermore, we have seen (in note 167) that different parts, once discriminated, necessarily fall into a determinate order, both by reason of definite gradations in their quality, and by reason of the fixed order of time-succession in which movements arouse them. But in all this nothing has been said of the comparative _measurement_ of one sensible space-total against another, or of the way in which, by summing our divers simple sensible space-experiences together, we end by constructing what we regard as the unitary, continuous, and infinite objective Space of the real world. To this more difficult inquiry we next pass.


THE CONSTRUCTION OF 'REAL' SPACE.


The problem breaks into two subordinate problems.

(1) _How is the subdivision and measurement of the several sensorial spaces completely effected?_ and

(2) _How do their mutual addition and fusion and reduction to the same scale, in a word, how does their synthesis, occur?_

I think that, as in the investigation just finished, we found ourselves able to get along without invoking any data but those that pure sensibility on the one hand, and the ordinary intellectual powers of discrimination and recollection on the other, were able to yield; so here we shall emerge from our more complicated quest with the conviction that all the facts can be accounted for on the supposition that no other mental forces have been at work save those we find everywhere else in psychology: sensibility, namely, for the data; and discrimination, association, memory, and choice for the rearrangements and combinations which they undergo.


1. _The Subdivision of the Original Sense-spaces._


How are spatial subdivisions brought to consciousness? in other words, How does spatial discrimination occur? The general subject of discrimination has been treated in a previous chapter. Here we need only inquire what are the conditions that make spatial discrimination so much finer in sight than in touch, and in touch than in hearing, smell, or taste.

_The first great condition is, that different points of the surface shall differ in the quality of their immanent sensibility,_ that is, that each shall carry its special local-sign. If the skin felt everywhere exactly alike, a foot-bath could be distinguished from a total immersion, as being smaller, but never distinguished from a wet face. The local-signs are indispensable; two points which have the same local-sign will always be felt as the same point. We do not judge them two unless we have discerned their sensations to be different.[168] Granted none but homogeneous irritants, that organ would then distinguish the greatest multiplicity of irritants--would count most stars or compass-points, or best compare the size of two wet surfaces--whose local sensibility was the least even. A skin whose sensibility shaded rapidly off from a focus, like the apex of a boil, would be better than a homogeneous integument for spatial perception. The retina, with its exquisitely sensitive fovea, has this peculiarity, and undoubtedly owes to it a great part of the minuteness with which we are able to subdivide the total bigness of the sensation it yields. On its periphery the local differences do not shade off very rapidly, and we can count there fewer subdivisions.

_But these local differences of feeling, so long as the surface is unexcited from without, are almost null._ I cannot feel them by a pure mental act of attention unless they belong to quite distinct parts of the body, as the nose and the lip, the finger-tip and the ear; their contrast needs the reinforcement of outward excitement to be felt. In the spatial muchness of a colic--or, to call it by the more spacious-sounding vernacular, of a 'bellyache'--one can with difficulty distinguish the north-east from the south-west corner, but can do so much more easily if, by pressing one's finger against the former region, one is able to make the pain there more intense.

_The local differences require then an adventitious sensation, superinduced upon them, to awaken the attention._ After the attention has once been awakened in this way, it may continue to be conscious of the unaided difference; just as a sail on the horizon may be too faint for us to notice until someone's finger, placed against the spot, has pointed it out to us, but may then remain visible after the finger has been withdrawn. But all this is true only on condition that separate points of the surface may be _exclusively_ stimulated. If the whole surface at once be excited from without, and homogeneously, as, for example, by immersing the body in salt water, local discrimination is not furthered. The local-signs, it is true, all awaken at once; but in such multitude that no one of them, with its specific quality, stands out in contrast with the rest. If, however, a single extremity be immersed, the contrast between the wet and dry parts is strong, and, at the surface of the water especially, the local-signs attract the attention, giving the feeling of a ring surrounding the member. Similarly, two or three wet spots separated by dry spots, or two or three hard points against the skin, will help to break up our consciousness of the latter's bigness. In cases of this sort, where points receiving an identical kind of excitement are, nevertheless, felt to be locally distinct, and the objective irritants are also judged multiple,--e.g., compass-points on skin or stars on retina,--the ordinary explanation is no doubt just, and we judge the outward causes to be multiple because we have discerned the local feelings of their sensations to be different.

_Capacity for partial stimulation is thus the second condition favoring discrimination._ A sensitive surface which has to be excited in all its parts at once can yield nothing but a sense of undivided largeness. This appears to be the case with the olfactory, and to all intents and purposes with the gustatory, surfaces. Of many tastes and flavors, even simultaneously presented, each affects the totality of its respective organ, each appears with the whole vastness given by that organ, and appears interpenetrated by the rest.[169]

I should have been willing some years ago to name without hesitation a third condition of discrimination--saying it would be most developed in that organ which is susceptible of the _most various qualities_ of feeling. The retina is unquestionably such an organ. The colors and shades it perceives are infinitely more numerous than the diversities of skin-sensation. And it can feel at once white and black, whilst the ear can in nowise so feel sound and silence. But the late researches of Donaldson, Blix, and Goldscheider,[170] on specific points for heat, cold, pressure, and pain in the skin; the older ones of Czermak (repeated later by Klug in Ludwig's laboratory), showing that a hot and a cold compass-point are no more easily discriminated as two than two of equal temperature; and some unpublished experiments of my own--all disincline me to make much of this condition now.[171] There is, however, one quality of sensation which is particularly exciting, and that is the _feeling of motion over any of our surfaces_. The erection of this into a separate elementary quality of sensibility is one of the most recent of psychological achievements, and is worthy of detaining us a while at this point.


_The Sensation of Motion over Surfaces._


_The feeling of motion_ has generally been assumed by physiologists to be impossible until the positions of _terminus a quo_ and _terminus ad quem_ are severally cognized, and the successive occupancies of these positions by the moving body are perceived to be separated by a distinct interval of time.[172] As a matter of fact, however, we cognize only the very slowest motions in this way. Seeing the hand of a clock at XII and afterwards at VI, we judge that it has moved through the interval. Seeing the sun now in the east and again in the west, I infer it to have passed over my head. But we can only _infer_ that which we already generically know in some more direct fashion, and it is experimentally certain that we have the feeling of motion given us as a direct and simple _sensation_. Czermak long ago pointed out the difference between seeing the motion of the second-hand of a watch, when we look directly at it, and noticing the fact of its having altered its position when we fix our gaze upon some other point of the dial-plate. In the first case we have a specific quality of sensation which is absent in the second. If the reader will find a portion of his skin--the arm, for example--where a pair of compass-points an inch apart are felt as one impression, and if he will then trace lines a tenth of an inch long on that spot with a pencil-point, he will be distinctly aware of the point's motion and vaguely aware of the direction of the motion. The perception of the motion here is certainly not derived from a pre-existing knowledge that its starting and ending points are separate positions in space, because positions in space ten times wider apart fail to be discriminated as such when excited by the dividers. It is the same with the retina. One's fingers when cast upon its peripheral portions cannot be counted--that is to say, the five retinal tracts which they occupy are not distinctly apprehended by the mind as five separate positions in space--and yet the slightest _movement_ of the fingers is most vividly perceived as movement and nothing else. It is thus certain that our sense of movement, being so much more delicate than our sense of position, cannot possibly be derived from it. _A curious observation by Exner_[173] completes the proof that movement is a primitive form of sensibility, by showing it to be much more delicate than our sense of succession in time. This very able physiologist caused two electric sparks to appear in rapid succession, one beside the other. The observer had to state whether the right-hand one or the left-hand one appeared first. When the interval was reduced to as short a time as 0.044 the discrimination of temporal order in the sparks became impossible. But Exner found that if the sparks were brought so close together in space that their irradiation-circles overlapped, the eye then felt their flashing as if it were the motion of a single spark from the point occupied by the first to the point occupied by the second, and the time-interval might then be made as small as 0.015 before the mind began to be in doubt as to whether the apparent motion started from the right or from the left. On the skin similar experiments gave similar results.

_Vierordt, at almost the same time,_[174] _called attention to certain persistent illusions, amongst which are these:_ If another person gently trace a line across our wrist or finger, the latter being stationary, it will feel to us as if the member were moving in the opposite direction to the tracing point. If, on the contrary, we move our limb across a fixed point, it will be seen as if the point were moving as well. If the reader will touch his forehead with his forefinger kept motionless, and then rotate the head so that the skin of the forehead passes beneath the finger's tip, he will have an irresistible sensation of the latter being itself in motion in the opposite direction to the head. So in abducting the fingers from each other; some may move and the rest be still still, but the still ones will feel as if they were actively separating from the rest. These illusions, according to Vierordt, are survivals of a primitive form of perception, when motion was felt as such, but ascribed to the whole content of consciousness, and not yet distinguished as belonging exclusively to one of its parts. When our perception is fully developed we go beyond the mere relative motion of thing and ground, and can ascribe absolute motion to one of these components of our total object, and absolute rest to another. When, in vision for example, the whole background moves together, we think that it is ourselves or our eyes which are moving; and any object in the foreground which may move relatively to the background is judged by us to be still. But primitively this discrimination cannot be perfectly made. The sensation of the motion spreads over all that we see and infects it. Any relative motion of object and retina both makes the object seem to move, and makes us feel ourselves in motion. Even now when our whole object moves we still get giddy; and we still see an apparent motion of the entire field of view, whenever we suddenly jerk our head and eyes or shake them quickly to and fro. Pushing our eyeballs gives the same illusion. We _know_ in all these cases what really happens, but the conditions are unusual, so our primitive sensation persists unchecked. So it does when clouds float by the moon. We _know_ the moon is still; but we _see_ it move even faster than the clouds. Even when we slowly move our eyes the primitive sensation persists under the victorious conception. If we notice closely the experience, we find that any object towards which we look appears moving to meet our eye.

But the most valuable contribution to the subject is the paper of G. H. Schneider,[175] who takes up the matter zoologically, and shows by examples from every branch of the animal kingdom that movement is the quality by which animals most easily attract each other's attention. The instinct of 'shamming death' is no shamming of death at all, but rather a paralysis through fear, which saves the insect, crustacean, or other creature from being _noticed at all_ by his enemy. It is parallelled in the human race by the breath-holding stillness of the boy playing 'I spy,' to whom the seeker is near; and its obverse side is shown in our involuntary waving of arms, jumping up and down, and so forth, when we wish to attract someone's attention at a distance. Creatures 'stalking' their prey and creatures hiding from their pursuers alike show how immobility diminishes conspicuity. In the woods, if we are quiet, the squirrels and birds will actually touch us. Flies will light on stuffed birds and stationary frogs.[176] On the other hand, the tremendous shock of feeling the thing we are sitting on begin to move, the exaggerated start it gives us to have an insect unexpectedly pass over our skin, or a cat noiselessly come and snuffle about our hand, the excessive reflex effects of tickling, etc., show how exciting the sensation of motion is _per se_. A kitten cannot help pursuing a moving ball. Impressions too faint to be cognized at all are immediately felt if they move. A fly sitting is unnoticed,--we feel it the moment it crawls. A shadow may be too faint to be perceived. As soon as it moves, however, we see it. Schneider found that a shadow, with distinct outline, and directly fixated, could still be perceived when moving, although its objective strength might be but half as great as that of a stationary shadow so faint as just to disappear. With a blurred shadow in indirect vision the difference in favor of motion was much greater--namely, 13.3:40.7. If we hold a finger between our closed eyelid and the sunshine we shall not notice its presence. The moment we move it to and fro, however, we discern it. Such visual perception as this reproduces the conditions of sight among the radiates.[177]

Enough has now been said to show that _in the education of spatial discrimination the motions of impressions across sensory surfaces must have been the principal agent_ in breaking up our consciousness of the surfaces into a consciousness of their parts. Even to-day the main function of the peripheral regions of our retina is that of sentinels, which, when beams of light move over them, cry 'Who goes there?' and call the fovea to the spot. Most parts of the skin do but perform the same office for the finger-tips. Of course finger-tips and fovea leave _some_ power of direct perception to marginal retina and skin respectively. But it is worthy of note that such perception is best developed on the skin of the most movable parts (the labors of Vierordt and his pupils have well shown this); and that in the blind, whose skin is exceptionally discriminative, it seems to have become so through the inveterate habit which most of them possess of twitching and moving it under whatever object may touch them, so as to become better acquainted with the conformation of the same. Czermak was the first to notice this. It may be easily verified. Of course _movement of surface under object is (for purposes of stimulation) equivalent to movement of object over surface._ In exploring the shapes and sizes of things by either eye or skin the movements of these organs are incessant and unrestrainable. Every such movement draws the points and lines of the object across the surface, imprints them a hundred times more sharply, and drives them home to the attention. The immense part thus played by movements in our perceptive activity is held by many psychologists[178] to prove that the muscles are themselves the space-perceiving organ. Not surface-sensibility, but 'the muscular sense,' is for these writers the original and only revealer of objective extension. But they have all failed to notice with what peculiar intensity muscular contractions call surface-sensibilities into play, and that the mere discrimination of impressions (quite apart from any question of measuring the space between them) largely depends on the mobility of the surface upon which they fall.[179]


2. _The Measurement of the sense-spaces against each other._


What precedes is all we can say in answer to the problem of discrimination. Turn now to that of measurement of the several spaces against each other, that being the first step in our constructing out of our diverse space-experiences the one space we believe in as that of the real world.

The first thing that seems evident is that we have no _immediate_ power of comparing together with any accuracy the extents revealed by different sensations. Our mouth-cavity feels indeed to itself smaller, and to the tongue larger, than it feels to the finger or eye, our tympanic membrane feels larger than our finger-tip, our lips feel larger than a surface equal to them on our thigh. So much comparison is immediate; but it is vague; and for anything exact we must resort to other help.

_The great agent in comparing the extent felt by one sensory surface with that felt by another, is superposition--superposition of one surface upon another, and superposition of one outer thing upon many surfaces._ Thus are exact equivalencies and common measures introduced, and the way prepared for numerical results.

Could we not superpose one part of our skin upon another, or one object on both parts, we should hardly succeed in coming to that knowledge of our own form which we possess. The original differences of bigness of our different parts would remain vaguely operative, and we should have no certainty as to how much lip was equivalent to so much forehead, how much finger to so much back.

But with the power of exploring one part of the surface by another we get a direct perception of cutaneous equivalencies. The primitive differences of bigness are overpowered when we feel by an immediate sensation that a certain length of thigh-surface is in contact with the entire palm and fingers. And when a motion of the opposite finger-tips draws a line first along this same length of thigh and then along the whole of the hand in question, we get a new manner of measurement, less direct but confirming the equivalencies established by the first. In these ways, by superpositions of parts and by tracing lines on different parts by identical movements, a person deprived of sight can soon learn to reduce all the dimensions of his body to a homogeneous scale. By applying the same methods to objects of his own size or smaller, he can with equal ease make himself acquainted with their extension stated in terms derived from his own bulk, palms, feet, cubits, spans, paces, fathoms (armspreads), etc. In these reductions it is to be noticed that _when the resident sensations of largeness of two opposed surfaces conflict, one of the sensations is chosen as the true standard and the other treated as illusory. Thus an empty tooth-socket is believed to be_ really smaller than the finger-tip which it will not admit, although it may _feel_ larger; and in general it may be said that the hand, as the almost exclusive organ of palpation, gives its own magnitude to the other parts, instead of having its size determined by them. In general, it is, as Fechner says, the extent felt by the more sensitive part to which the other extents are reduced.[180]

But even though exploration of one surface by another were impossible, we could always measure our various surfaces against each other by applying the same extended object first to one and then to another. We should of course have the alternative of supposing that the object itself waxed and waned as it glided from one place to another (cf. above, p. 141); but the principle of simplifying as much as possible our world would soon drive us out of that assumption into the easier one that objects as a rule keep their sizes, and that most of our sensations are affected by errors for which a constant allowance must be made.

In the retina there is no reason to suppose that the bignesses of two impressions (lines or blotches) falling on different regions are primitively felt to stand in any exact mutual ratio. It is only when the impressions come from the _same object_ that we judge their sizes to be the same. And this, too, only when the relation of the object to the eye is believed to be on the whole unchanged. When the object by moving changes its relations to the eye the sensation excited by its image even on the same retinal region becomes so fluctuating that we end by ascribing no absolute import whatever to the retinal space-feeling which at any moment we may receive. So complete does this overlooking of retinal magnitude become that it is next to impossible to compare the visual magnitudes of objects at different distances without making the experiment of superposition. We cannot say beforehand how much of a distant house or tree our finger will cover. The various answers to the familiar question, How large is the moon?--answers which vary from a cartwheel to a wafer--illustrate this most strikingly. The hardest part of the training of a young draughtsman is his learning to feel directly the retinal (i.e. primitively sensible) magnitudes which the different objects in the field of view subtend. To do this he must recover what Ruskin calls the 'innocence of the eye'--that is, a sort of childish perception of stains of color merely as such, without consciousness of what they mean.

With the rest of us this innocence is lost. _Out of all the visual magnitudes of each known object we have selected one as the_ REAL _one to think of, and degraded all the others to serve as its signs_. This 'real' magnitude is determined by æsthetic and practical interests. It is that which we get when the object is at the distance most propitious for exact visual discrimination of its details. This is the distance at which we hold anything we are examining. Farther than this we see it too small, nearer too large. And the larger and the smaller feeling vanish in the act of suggesting this one, their more important _meaning_. As I look along the dining-table I overlook the fact that the farther plates and glasses _feel_ so much smaller than my own, for I _know_ that they are all equal in size; and the feeling of them, which is a present sensation, is eclipsed in the glare of the knowledge, which is a merely imagined one.

If the inconsistencies of sight-spaces _inter se_ can thus be reduced, of course there can be no difficulty in equating sight-spaces with spaces given to touch. In this equation it is probably the touch-feeling which prevails as real and the sight which serves as sign--a reduction made necessary not only by the far greater constancy of felt over seen magnitudes, but by the greater practical interest which the sense of touch possesses for our lives. As a rule, things only benefit or harm us by coming into direct contact with our skin: sight is only a sort of anticipatory touch; the latter is, in Mr. Spencer's phrase, the 'mother-tongue of thought,' and the handmaid's idiom must be translated into the language of the mistress before it can speak clearly to the mind.[181]

Later on we shall see that the feelings excited in the joints when a limb moves are used as signs of the path traversed by the extremity. But of this more anon. As for the equating of sound-, smell-, and taste-volumes with those yielded by the more discriminative senses, they are too vague to need any remark. It may be observed of pain, however, that its size has to be reduced to that of the normal tactile size of the organ which is its seat. A finger with a felon on it, and the pulses of the arteries therein, both 'feel' larger than we believe they really 'are.'

It will have been noticed in the account given that _when two sensorial space-impressions, believed to come from the same object, differ, then_ THE ONE MOST INTERESTING, _practically or æsthetically_, IS JUDGED TO BE THE TRUE ONE. This law of interest holds throughout--though a permanent interest, like that of touch, may resist a strong but fleeting one like that of pain, as in the case just given of the felon.


3. _The Summation of the Sense-spaces._


Now for the next step in our construction of real space: _How are the various sense-spaces added together into a consolidated and unitary continuum?_ For they are, in man at all events, incoherent at the start.

      *       *       *       *       *

Here again the first fact that appears is that _primitively our space-experiences form a chaos, out of which we have no immediate faculty for extricating them. Objects of different sense-organs, experienced together, do not in the first instance appear either inside or alongside or far outside of each other, neither spatially continuous nor discontinuous, in any definite sense of these words._ The same thing is almost as true of objects felt by different parts of the same organ before discrimination has done its finished work. The most we can say is that all our space-experiences together form an _objective total_ and that this _objective total_ is vast.

Even now the space inside our mouth, which is so intimately known and accurately measured by its inhabitant the tongue, can hardly be said to have its internal directions and dimensions known in any exact relation to those of the larger world outside. It forms almost a little world by itself. Again, when the dentist excavates a small cavity in one of our teeth, we feel the hard point of his instrument scraping, in distinctly differing directions, a surface which seems to our sensibility vaguely larger than the subsequent use of the mirror tells us it 'really' is. And though the directions of the scraping differ so completely _inter se_, not one of them can be identified with the particular direction in the outer world to which it corresponds. The space of the tooth-sensibility is thus really a little world by itself, which can only become congruent with the outer space-world by farther experiences which shall alter its bulk, identify its directions, fuse its margins, and finally imbed it as a definite part within a definite whole. And even though every joint's rotations should be felt to vary _inter se_ as so many differences of direction in a common room; even though the same were true of diverse tracings on the skin, and of diverse tracings on the retina respectively, it would still not follow that feelings of direction, on these different surfaces, are intuitively comparable among each other, or with the other directions yielded by the feelings of the semi-circular canals. It would not follow that we should immediately judge the relations of them all to each other in one space-world.

If with the arms in an unnatural attitude we 'feel' things, we are perplexed about their shape, size, and position. Let the reader lie on his back with his arms stretched above his head, and it will astonish him to find how ill able he is to recognize the geometrical relations of objects placed within reach of his hands. But the geometrical relations here spoken of are nothing but identities recognized between the directions and sizes perceived in this way and those perceived in the more usual ways. The two ways do not fit each other intuitively.

How lax the connection between the system of visual and the system of tactile directions is in man, appears from the facility with which microscopists learn to reverse the movements of their hand in manipulating things on the stage of the instrument. To move the slide to the _seen_ left they must draw it to the _felt_ right. But in a very few days the habit becomes a second nature. So in tying our cravat, shaving before a mirror, etc., the right and left sides are inverted, and the directions of our hand movements are the opposite of what they seem. Yet this never annoys us. Only when by accident we try to tie the cravat of another person do we learn that there are two ways of combining sight and touch perceptions. Let any one try for the first time to write or draw while looking at the image of his hand and paper in a mirror, and he will be utterly bewildered. But a very short training will teach him to undo in this respect the associations of his previous lifetime.

Prisms show this in an even more striking way. If the eyes be armed with spectacles containing slightly prismatic glasses with their bases turned, for example, towards the right, every object looked at will be apparently translocated to the left; and the hand put forth to grasp any such object will make the mistake of passing beyond it on the left side. But less than an hour of practice in wearing such spectacles rectifies the judgment so that no more mistakes are made. In fact the new-formed associations are already so strong, that when the prisms are first laid aside again the opposite error is committed, the habits of a lifetime violated, and the hand now passed to the right of every object which it seeks to touch.

The primitive chaos thus subsists to a great degree through life so far as our immediate sensibility goes. We feel our various objects and their bignesses, together or in succession; but so soon as it is a question of the order and relations of many of them at once our intuitive apprehension remains to the very end most vague and incomplete. Whilst we are attending to one, or at most to two or three objects, all the others _lapse_, and the most we feel of them is that they still linger on the outskirts and can be caught again by turning in a certain way. Nevertheless _throughout all this confusion we conceive of a world spread out in a perfectly fixed and orderly fashion, and we believe in its existence. The question is: How do this conception and this belief arise? How is the chaos smoothed and straightened out?_

      *       *       *       *       *

Mainly by two operations: Some of the experiences are apprehended to exist out- and alongside of each other, and others are apprehended to interpenetrate each other, and to occupy the same room. In this way what was incoherent and irrelative ends by being coherent and definitely related; nor is it hard to trace the principles, by which the mind is guided in this arrangement of its perceptions, in detail.

In the first place, following the great intellectual law of economy, we simplify, unify, and identify as much as we possibly can. _Whatever sensible data can be attended to together we locate together. Their several extents seem one extent. The place at which each appears is held to be the same with the place at which the others appear. They become, in short, so many properties of_ ONE AND THE SAME REAL THING. This is the first and great commandment, the fundamental 'act' by which our world gets spatially arranged.

In this _coalescence in a 'thing_,' one of the coalescing sensations is held to _be_ the thing, the other sensations are taken for its more or less accidental _properties_, or modes of appearance.[182] The sensation chosen to be the thing essentially is the most constant and practically important of the lot; most often it is hardness or weight. But the hardness or weight is never without tactile bulk; and as we can always see something in our hand when we feel something there, we equate the bulk felt with the bulk seen, and thenceforward this common bulk is also apt to figure as of the essence of the 'thing.' Frequently a shape so figures, sometimes a temperature, a taste, etc.; but for the most part temperature, smell, sound, color, or whatever other phenomena may vividly impress us simultaneously with the bulk felt or seen, figure among the accidents. Smell and sound impress us, it is true, when we neither see nor touch the thing; but they are strongest when we see or touch, so we locate the _source_ of these properties within the touched or seen space, whilst the properties themselves we regard as overflowing in a weakened form into the spaces filled by other things. _In all this, it will be observed, the sense-data whose spaces coalesce into one are yielded by different sense-organs._ Such data have no tendency to displace each other from consciousness, but can be attended to together all at once. Often indeed they vary concomitantly and reach a maximum together. We may be sure, therefore, that the general rule of our mind is to locate IN _each other all_ sensations which are associated in simultaneous experience, and do not interfere with each other's perception.[183]

_Different impressions on the same sense-organ_ do interfere with each other's perception, and cannot well be attended to at once. Hence _we do not locate them in each other's spaces, but arrange them in a serial order of exteriority, each alongside of the rest, in a space larger than that which any one sensation brings._ This larger space, however, is an object of conception rather than of direct intuition, and bears all the marks of being constructed piecemeal by the mind. The blind man forms it out of tactile, locomotor, and auditory experiences, the seeing man out of visual ones almost exclusively. As the visual construction is the easiest to understand, let us consider that first.

      *       *       *       *       *

Every single visual sensation or 'field of view' is limited. To get a new field of view for our object the old one must disappear. But the disappearance may be only partial. Let the first field of view be A B C. If we carry our attention to the limit C, it ceases to be the limit, and becomes the centre of the field, and beyond it appear fresh parts where there were none before:[184] A B C changes, in short, to C D E. But although the parts A B are lost to sight, yet their image abides in the memory; and if we think of our first object A B C as having existed or as still existing at all, we must think of it as it was originally presented, namely, as spread out from C in one direction just as C D E is spread out in another. A B and D E can never coalesce in one place (as they could were they objects of different senses) because they can never be perceived at once: we must lose one to see the other. So (the letters standing now for 'things') we get to conceive of the successive fields of things after the analogy of the several things which we perceive in a single field. They must be out- and alongside of each other, and we conceive that their juxtaposed spaces must make a larger space. A B C + C D E must, in short, be imagined to exist in the form of A B C D E or not imagined at all.

We can usually recover anything lost from sight by moving our attention and our eyes back in its direction; and through these constant changes every field of seen things comes at last to be thought of as always having a fringe of _other things possible to be seen_ spreading in all directions round about it. Meanwhile the movements concomitantly with which the various fields alternate are also felt and remembered; and gradually (through association) this and that movement come in our thought to suggest this or that extent of fresh objects introduced. Gradually, too, since the objects vary indefinitely in kind, we abstract from their several natures and think separately of their mere extents, of which extents the various movements remain as the only constant introducers and associates. More and more, therefore, do we think of movement and seen extent as mutually involving each other, until at last (with Bain and J. S. Mill) we may get to regard them as synonymous, and say, "What is the _meaning of the word extent_, unless it be possible movement?"[185] We forget in this conclusion that (whatever intrinsic extensiveness the movements may appear endowed with), that seen spreadoutness which is the pattern of the abstract extensiveness which we imagine came to us originally from the retinal sensation.

The muscular sensations of the eyeball _signify_ this sort of visible spreadoutness, just as this visible spreadoutness may come in later experience to _signify_ the 'real' bulks, distances, lengths and breadths known to touch and locomotion.[186] To the very end, however, in us seeing men, the quality, the nature, the _sort of thing we mean_ by extensiveness, would seem to be the sort of feeling which our retinal stimulations bring.

      *       *       *       *       *

In one deprived of sight the principles by which the notion of real space is constructed are the same. Skin-feelings take in him the place of retinal feelings in giving the quality of lateral spreadoutness, as our attention passes from one extent of them to another, awakened by an object sliding along. Usually the moving object is our hand; and feelings of movement in our joints invariably accompany the feelings in the skin. But the feeling of the skin is what the blind man _means_ by his skin; so the size of the skin-feelings stands as the absolute or real size, and the size of the joint-feelings becomes a sign of these. Suppose, for example, a blind baby with (to make the description shorter) a blister on his toe, exploring his leg with his finger-tip and feeling a pain shoot up sharply the instant the blister is touched. The experiment gives him four different kinds of sensation--two of them protracted, two sudden. The first pair are the movement-feeling in the joints of the upper limb, and the movement-feeling on the skin of the leg and foot. These, attended to together, have their extents identified as one objective space--the hand moves through the same space in which the leg lies. The second pair of objects are the pain in the blister, and the peculiar feeling the blister gives to the finger. Their spaces also fuse; and as each marks the end of a peculiar movement-series (arm moved, leg stroked), the movement-spaces are _emphatically_ identified with each other at _that_ end. Were there other small blisters distributed down the leg, there would be a number of these emphatic points; the movement-spaces would be identified, not only as totals, but point for point.[187]

Just so with spaces beyond the body's limits. Continuing the joint-feeling beyond the toe, the baby hits another object, which he can still think of when he brings his hand back to its blister again. That object at the end of that joint-feeling means a new place for him, and the more such objects multiply in his experience the wider does the space of his conception grow. If, wandering through the woods to-day by a new path, I find myself suddenly in a glade which affects my senses exactly as did another I reached last week at the end of a different walk, I believe the two identical affections to present the same persisting glade, and infer that I have attained it by two differing roads. The spaces walked over grow congruent by their extremities; though apart from the common sensation which those extremities give me, I should be under no necessity of connecting one walk with another at all. The case in no whit differs when shorter movements are concerned. If, moving first one arm and then another, the blind child gets the same kind of sensation upon the hand, and gets it again as often as he repeats either process, he judges that he has touched the same object by both motions, and concludes that the motions terminate in a common place. From place to place marked in this way he moves, and adding the places moved through, one to another, he builds up his notion of the extent of the outer world. The seeing man's process is identical; only his units, which may be successive bird's-eye views, are much larger than in the case of the blind.


FEELINGS IN JOINTS AND FEELINGS IN MUSCLES.

1. _Feelings of Movement in Joints._


I have been led to speak of feelings which arise in joints. As these feelings have been too much neglected in Psychology hitherto, in entering now somewhat minutely into their study I shall probably at the same time freshen the interest of the reader, which under the rather dry abstractions of the previous pages may presumably have flagged.

When, by simply flexing my right forefinger on its metacarpal joint, I trace with its tip an inch on the palm of my left hand, is my feeling of the size of the inch purely and simply a feeling in the skin of the palm, or have the muscular contractions of the right hand and forearm anything to do with it? In the preceding pages I have constantly assumed spatial sensibility to be an affair of surfaces. At first starting, the consideration of the 'muscular sense' as a space-measurer was postponed to a later stage. Many writers, of whom the foremost was Thomas Brown, in his _Lectures on the Philosophy of the Human Mind_, and of whom the latest is no less a Psychologist than Prof. Delbœuf,[188] hold that the consciousness of active muscular motion, aware of its own amount, is the _fons et origo_ of all spatial measurement. It would seem to follow, if this theory were true, that two skin-feelings, one of a large patch, one of a small one, possess their difference of spatiality, not as an immediate element, but solely by virtue of the fact that the large one, to get its points _successively_ excited, demands more muscular contraction than the small one does. Fixed associations with the several amounts of muscular contraction required in this particular experience would thus explain the apparent sizes of the skin-patches, which sizes would consequently not be primitive data but derivative results.

_It seems to me that no evidence of the muscular measurements in question exists;_ but that all the facts may be explained by surface-sensibility, provided we take that of the joint-surfaces also into account.

The most striking argument, and the most obvious one, which an upholder of the muscular theory is likely to produce is undoubtedly this fact: if, with closed eyes, we trace figures in the air with the extended forefinger (the motions may occur from the metacarpal-, the wrist-, the elbow-, or the shoulder-joint indifferently), what we are _conscious of_ in each case, and indeed most acutely conscious of, is the geometric path described by the finger-tip. Its angles, its subdivisions, are all as distinctly felt as if seen by the eye; and yet the surface of the finger-tip receives no impression at all.[189] But with each variation of the figure, the muscular contractions vary, and so do the feelings which these yield. Are not these latter the sensible data that make us aware of the lengths and directions we discern in the traced line?

Should we be tempted to object to this supposition of the advocate of perception by muscular feelings, that we have _learned_ the spatial significance of these feelings by reiterated experiences of _seeing_ what figure is drawn when each special muscular grouping is felt, so that in the last resort the muscular space feelings would be derived from retinal-surface feelings, our opponent might immediately hush us by pointing to the fact that in persons born blind the phenomenon in question is even more perfect than in ourselves.

If we suggest that the blind may have originally traced the figures on the cutaneous surface of cheek, thigh, or palm, and may now remember the specific figure which each present movement formerly caused the skin-surface to perceive, he may reply that the delicacy of the motor perception far exceeds that of most of the cutaneous surfaces; that, in fact, we can feel a figure traced only in its differentials, so to speak,--a figure which we merely _start_ to trace by our finger-tip, a figure which, traced in the same way _on_ our finger-tip by the hand of another, is almost if not wholly unrecognizable.

      *       *       *       *       *

The champion of the muscular sense seems likely to be triumphant _until we invoke the articular cartilages_, as internal surfaces whose sensibility is called in play by every movement we make, however delicate the latter may be.

To establish the part they play in our geometrizing, it is necessary to review a few facts. It has long been known by medical practitioners that, in patients with cutaneous anæsthesia of a limb, whose muscles also are insensible to the thrill of the faradic current, a very accurate sense of the way in which the limb may be flexed or extended by the hand of another may be preserved.[190] On the other hand, we may have this sense of movement impaired when the tactile sensibility is well preserved. That the pretended feeling of outgoing innervation can play in these cases no part, is obvious from the fact that the movements by which the limb changes its position are passive ones, imprinted on it by the experimenting physician. The writers who have sought a _rationale_ of the matter have consequently been driven by way of exclusion to assume the articular surfaces to be the seat of the perception in question.[191]

_That the joint-surfaces are sensitive_ appears evident from the fact that in inflammation they become the seat of excruciating pains, and from the perception by everyone who lifts weights or presses against resistance, that every increase of the force opposing him betrays itself to his consciousness principally by the starting-out of new feelings or the increase of old ones, in or about the joints. If the structure and mode of mutual application of two articular surfaces be taken into account, it will appear that, granting the surfaces to _be_ sensitive, no more favorable mechanical conditions could be possible for the delicate calling of the sensibility into play than are realized in the minutely graduated rotations and firmly resisted variations of pressure involved in every act of extension or flexion. Nevertheless it is a great pity that we have as yet no direct testimony, no expressions from patients with healthy joints accidentally laid open, of the impressions they experience when the cartilage is pressed or rubbed.

The first approach to direct evidence, so far as I know, is contained in the paper of Lewinski,[192] published in 1879. This observer had a patient the inner half of whose leg was anæsthetic. When this patient stood up, he had a curious illusion about the position of his limb, which disappeared the moment he lay down again: he thought himself _knock-kneed_. If, as Lewinski says, we assume the inner half of the joint to share the insensibility of the corresponding part of the skin, then he _ought_ to feel, when the joint-surfaces pressed against each other in the act of standing, the outer half of the joint most strongly. But this is the feeling he would also get whenever it was by any chance sought to force his leg into a knock-kneed attitude. Lewinski was led by this case to examine the feet of certain ataxic patients with imperfect sense of position. He found in every instance that when the toes were flexed _and drawn upon_ at the same time (the joint-surfaces drawn asunder) all sense of the amount of flexion disappeared. On the contrary, when he pressed a toe _in_, whilst flexing it, the patient's appreciation of the amount of flexion was much improved, evidently because the artificial increase of articular pressure made up for the pathological insensibility of the parts.

Since Lewinski's paper an important experimental research by A. Goldscheider[193] has appeared, which completely establishes our point. This patient observer caused his fingers, arms, and legs to be passively rotated upon their various joints in a mechanical apparatus which registered both the velocity of movement impressed and the amount of angular rotation. No active muscular contraction took place. The minimal felt amounts of rotation were in all cases surprisingly small, being much less than a single angular degree in all the joints except those of the fingers. Such displacements as these, the author says (p. 490), can hardly be detected by the eye. The point of application of the force which rotated the limb made no difference in the result. Rotations round the hip-joint, for example, were as delicately felt when the leg was hung by the heel as when it was hung by the thigh whilst the movements were performed. Anæsthesia of the skin produced by induction-currents also had no disturbing effect on the perception, nor did the various degrees of pressure of the moving force upon the skin affect it. It became, in fact, all the more distinct in proportion as the concomitant pressure-feelings were eliminated by artificial anæsthesia. When the joints themselves, however, were made artificially anæsthetic the perception of the movement grew obtuse and the angular rotations had to be much increased before they were perceptible. All these facts prove according to Herr Goldscheider, that _the joint surfaces and these alone are the starting point of the impressions by which the movements of our members are immediately perceived._

Applying this result, which seems invulnerable, to the case of the tracing finger-tip, we see that our perception of the latter gives no countenance to the theory of the muscular sense. _We indubitably localize the finger-tip at the successive points of its path by means of the sensations which we receive from our joints._ But if this is so, it may be asked, why do we feel the figure to be traced, not within the joint itself, but in such an altogether different place? And why do we feel it so much larger than it really is?

I will answer these questions by asking another: Why do we move our joints at all? Surely to gain something more valuable than the insipid joint-feelings themselves. And these more interesting feelings are in the main produced upon the _skin_ of the moving part, or of some other part over which it passes, or upon the eye. With movements of the fingers we explore the configuration of all real objects with which we have to deal, our own body as well as foreign things. Nothing that interests us is located in the joint; everything that interests us either _is_ some part of our skin, or is something that we see as we handle it. The cutaneously felt and the seen extents come thus to figure as the important things for us to concern ourselves with. Every time the joint moves, even though we neither see, nor feel cutaneously, the reminiscence of skin-events and sights which formerly coincided with that extent of movement, ideally awaken as the movement's import, and the mind drops the present sign to attend to the import alone. The joint-sensation itself, as such, does not disappear in the process. A little attention easily detects it, with all its fine peculiarities, hidden beneath its vaster suggestions; so that really the mind has two space-perceptions before it, congruent in form but different in scale and place, either of which exclusively it may notice, or both at once,--the joint-space which it _feels_ and the real space which it _means_.

The joint-spaces serve so admirably as signs because of their capacity for _parallel variation_ to all the peculiarities of external motion. There is not a direction in the real world nor a ratio of distance which cannot be matched by some direction or extent of joint-rotation. Joint-feelings, like all feelings, are roomy. Specific ones are contrasted _inter se_ as different directions are contrasted within the same extent. If I extend my arm straight out at the shoulder, the rotation of the shoulder-joint will give me one feeling of movement; if then I sweep the arm forward, the same joint will give me another feeling of movement. Both these movements are felt to happen in space, and differ in specific quality. Why shall not the specificness of the quality just consist in the feeling of a peculiar _direction?_[194] Why may not the several joint-feelings _be_ so many perceptions of movement in so many different directions? That we cannot explain why they _should_ is no presumption that they _do_ not, for we never can explain why any sense-organ should awaken the sensation it does.

But if the joint-feelings are directions and extents, standing in relation to each other, the task of association in interpreting their import in eye- or skin-terms is a good deal simplified. Let the movement _bc_, of a certain joint, derive its absolute space-value from the cutaneous feeling it is always capable of engendering; then the longer movement _abcd_ of the same joint will be judged to have a greater space-value, even though it may never have wholly merged with a skin-experience. So of differences of direction: so much joint-difference = so much skin-difference; therefore, more joint-difference = more skin-difference. _In fact, the joint-feeling can excellently serve as a map on a reduced scale, of a reality which the imagination can identify at its pleasure with this or that sensible extension simultaneously known in some other way._

When the joint-feeling in itself acquires an emotional interest,--which happens whenever the joint is inflamed and painful,--the secondary suggestions fail to arise, and the movement is felt where it is, and in its intrinsic scale of magnitude.[195]

The localization of the joint-feeling in a space simultaneously known otherwise (i.e. to eye or skin), is what is commonly called the _extradition or eccentric projection of the feeling_. In the preceding chapter I said a good deal on this subject; but we must now see a little more closely just what happens in this instance of it. The content of the joint-feeling, to begin with, is an object, and _is_ in itself a place. For it to be _placed_, say _in the elbow_, the elbow as seen or handled must already have become another object for the mind, and with its place as thus known, the place which the joint-feeling fills must coalesce. That the latter should be felt 'in the elbow' is therefore a 'projection' of it into the place of another object as much as its being felt in the finger-tip or at the end of a cane can be. But when we say 'projection' we generally have in our mind the notion of a _there_ as contrasted with a _here_. What is the _here_ when we say that the joint-feeling is _there_? The 'here' seems to be the spot which the mind has chosen for its own post of observation, usually some place within the head, but sometimes within the throat or breast--not a rigorously fixed spot, but a region from any portion of which it may send forth its various acts of attention. Extradition from either of _these_ regions is the common law under which we perceive the whereabouts of the north star, of our own voice, of the contact of our teeth with each other, of the tip of our finger, of the point of our cane on the ground, or of a movement in our elbow-joint.

But _for the distance between the 'here' and the 'there' to be felt, the entire intervening space must be itself an object of perception._ The consciousness of this intervening space is the _sine quâ non_ of the joint-feeling's projection to the farther end of it. When it is filled by our own bodily tissues (as where the projection only goes as far as the elbow or finger-tip) we are sensible of its extent alike by our eye, by our exploring movements, and by the resident sensations which fill its length. When it reaches beyond the limits of our body, the resident sensations are lacking, but limbs and hand and eye suffice to make it known. Let me, for example, locate a feeling of motion coming from my elbow-joint in the point of my cane a yard beyond my hand. Either I see this yard as I flourish the cane, and the seen end of it then absorbs my sensation just as my seen elbow might absorb it, or I am blind and imagine the cane as an object continuing my arm, either because I have explored both arm and cane with the other hand, or because I have pressed them both along my body and leg. If I project my joint-feeling farther still, it is by a conception rather than a distinct imagination of the space. I _think_: 'farther,' 'thrice as far,' etc.; and thus get a symbolic image of a distant path at which I point.[196] But the 'absorption' of the joint-feeling by the distant spot, in whatever terms the latter may be apprehended, is never anything but that coalescence into one 'thing' already spoken of on page 184, of whatever different sensible objects interest our attention at once.


2. _Feelings of Muscular Contraction._


Readers versed in psychological literature will have missed, in our account thus far, the usual invocation of 'the muscular sense.' This word is used with extreme vagueness to cover all resident sensations, whether of motion or position, in our members, and even to designate the supposed feeling of efferent discharge from the brain. We shall later see good reason to deny the existence of the latter feeling. We have accounted for the better part at least of the resident feelings of motion in limbs by the sensibility of the articular surfaces. The skin and ligaments also must have feelings awakened as they are stretched or squeezed in flexion or extension. And I am inclined to think that _the sensations of our contracting muscles themselves probably play as small a part in building up our exact knowledge of space as any class of sensations which we possess._ The muscles, indeed, play an all-important part, but it is through the remote effect of their contractions on other sensitive parts, not through their own resident sensations being aroused. In other words, _muscular contraction is only indirectly instrumental, in giving us space-perceptions, by its effects on surfaces._ In skin and retina it produces a motion of the stimulus upon the surface; in joints it produces a motion of the surfaces upon each other--such motion being by far the most delicate manner of exciting the surfaces in question. One is tempted to doubt whether the muscular sensibility as such plays even a subordinate part as _sign_ of these more immediately geometrical perceptions which are so uniformly associated with it as effects of the contraction objectively viewed.

For this opinion many reasons can be assigned. First, it seems _a priori_ improbable that such organs as muscles should give us feelings whose variations bear any exact proportion to the spaces traversed when they contract. As G. E. Müller says,[197] their sensory nerves must be excited either chemically or by mechanical compression whilst the contractions last, and in neither case can the excitement be proportionate to the position into which the limb is thrown. The chemical state of the muscle depends on the _previous_ work more than on the actually present contraction; and the internal pressure of it depends on the resistance offered more than on the shortening attained. _The intrinsic muscular sensations are likely therefore to be merely those of massive strain or fatigue, and to carry no accurate discrimination with them of lengths of path moved through._

Empirically we find this probability confirmed by many facts. The judicious A. W. Volkmann observes[198] that:

"Muscular feeling gives tolerably fine evidence as to the _existence_
of movement, but hardly any direct information about its extent or
direction. We are not aware that the contractions of a _supinator
longus_ have a wider range than those of a _supinator brevis_;
and that the fibres of a bipenniform muscle contract in opposite
directions is a fact of which the muscular feeling itself gives not
the slightest intimation. Muscle-feeling belongs to that class of
general sensations which tell us of our inner states, but not of outer
relations; it does not belong among the space-perceiving senses."

E. H. Weber in his article Tastsinn called attention to the fact that muscular movements as large and strong as those of the diaphragm go on continually without our perceiving them as motion.

G. H. Lewes makes the same remark. When we think of our muscular sensations as movements in space, it is because we have ingrained with them in our imagination a movement on a surface simultaneously felt.

"Thus whenever we breathe there is a contraction of the muscles of
the ribs and the diaphragm. Since we _see_ the chest expanding, we
know it as a movement and can only think of it as such. But the
diaphragm itself is not seen, and consequently by no one who is not
physiologically enlightened on the point is this diaphragm thought of
in movement. Nay, even when told by a physiologist that the diaphragm
moves at each breathing, every one who has not seen it moving
downward pictures it as an upward movement, because the chest moves
upward."[199]

A personal experience of my own seems strongly to corroborate this view. For years I have been familiar, during the act of gaping, with a large, round, smooth sensation in the region of the throat, a sensation characteristic of gaping and nothing else, but which, although I had often wondered about it, never suggested to my mind the motion of anything. The reader probably knows from his own experience exactly what feeling I mean. It was not till one of my students told me, that I learned its objective cause. If we look into the mirror while gaping, we see that at the moment we have this feeling the hanging palate _rises_ by the contraction of its intrinsic muscles. The contraction of these muscles and the compression of the palatine mucous membrane are what occasion the feeling; and I was at first astonished that, coming from so small an organ, it could appear so voluminous. Now the curious point is this--that no sooner had I learned by the eye its objective space-significance, than I found myself enabled mentally to _feel_ it as a movement upwards of a body in the situation of the uvula. When I now have it, my fancy _injects_ it, so to speak, with the image of the rising uvula; and it _absorbs_ the image easily and naturally. In a word, a muscular contraction gave me a sensation whereof I was unable during forty years to interpret a motor meaning, of which two glances of the eye made me permanently the master. To my mind no further proof is needed of the fact that muscular contraction, merely as such, need not be perceived directly as so much motion through space.

Take again the contractions of the muscles which make the eyeball rotate. The feeling of these is supposed by many writers to play the chief part in our perceptions of extent. The space seen between two things _means_, according to these authors, nothing but the amount of contraction which is needed to carry the _fovea_ from the first thing to the second. But close the eyes and note the contractions in themselves (even when coupled as they still are with the delicate surface sensations of the eyeball rolling under the lids), and we are surprised at finding how vague their space-import appears. Shut the eyes and roll them, and you can with no approach to accuracy tell the outer object which shall first be seen when you open them again.[200] Moreover, if our eye-muscle-contractions had much to do with giving us our sense of seen extent, we ought to have a natural illusion of which we find no trace. Since the feeling in the muscles grows disproportionately intense as the eyeball is rolled into an extreme eccentric position, all places on the extreme _margin_ of the field of view ought to appear farther from the centre than they really are, for the fovea cannot get to them without an amount of this feeling altogether in excess of the amount of actual rotation.[201] When we turn to the muscles of the body at large we find the same vagueness. Goldscheider found that the minimal perceived rotation of a limb about a joint was no less when the movement was 'active' or produced by muscular contraction than when it was 'passively' impressed.[202] The consciousness of active movement became so blunt when the joint (alone!) was made anæsthetic by faradization, that it became evident that the feeling of contraction could never be used for _fine_ discrimination of extents. And that it was not used for coarse discriminations appeared clear to Goldscheider from certain other results which are too circumstantial for me to quote in detail.[203] His general conclusion is that we feel our movements exclusively in our articular surfaces, and that our muscular contractions in all probability hardly occasion this sort of perception at all.[204]

My conclusion is that the 'muscular sense' must fall back to the humble position from which Charles Bell raised it, and no longer figure in Psychology as the leading organ in space-perception which it has been so long 'cracked up' to be.

      *       *       *       *       *

Before making a minuter study of Space as apprehended by the eye, we must turn to see what we can discover of space as known to the blind. But as we do so, let us cast a glance upon the results of the last pages, and ask ourselves once more whether the building up of orderly space-perceptions out of primitive incoherency requires any mental powers beyond those displayed in ordinary intellectual operations. I think it is obvious--granting the spacial _quale_ to exist in the primitive sensations--that discrimination, association, addition, multiplication, and division, blending into generic images, substitution of similars, selective emphasis, and abstraction from uninteresting details, are quite capable of giving us all the space-perceptions we have so far studied, without the aid of any mysterious 'mental chemistry' or power of 'synthesis' to create elements absent from the original data of feeling. It cannot be too strongly urged in the face of mystical attempts, however learned, that there is not a landmark, not a length, not a point of the compass in real space which _is_ not some _one_ of our feelings, either experienced directly as a presentation or ideally suggested by another feeling which has come to serve as its sign. In degrading some sensations to the rank of signs and exalting others to that of realities signified, we smooth out the wrinkles of our first chaotic impressions and make a continuous order of what was a rather incoherent multiplicity. But the _content_ of the order remains identical with that of the multiplicity--sensational both, through and through.


HOW THE BLIND PERCEIVE SPACE.


The blind man's construction of real space differs from that of the seeing man most obviously in the larger part which synthesis plays in it, and the relative subordination of analysis. The seeing baby's eyes take in the whole room at once, and discriminative attention must arise in him before single objects are visually discerned. The blind child, on the contrary, must form his mental image of the room by the addition, piece to piece, of parts which he learns to know successively. With our eyes we may apprehend instantly, in an enormous bird's-eye view, a landscape which the blind man is condemned to build up bit by bit after weeks perhaps of exploration. We are exactly in his predicament, however, for spaces which exceed our visual range. We think the ocean as a whole by multiplying mentally the impression we get at any moment when at sea. The distance between New York and San Francisco is computed in days' journeys; that from earth to sun is so many times the earth's diameter, etc.; and of longer distances still we may be said to have no adequate mental image whatever, but only numerical verbal symbols.

But the symbol will often give us the emotional effect of the perception. Such expressions as the abysmal vault of heaven, the endless expanse of ocean, etc., summarize many computations to the imagination, and give the sense of an enormous horizon. So it seems with the blind. They multiply mentally the amount of a distinctly felt freedom to move, and gain the immediate sense of a vaster freedom still. Thus it is that blind men are never without the consciousness of their horizon. They all enjoy travelling, especially with a companion who can describe to them the objects they pass. On the prairies they feel the great openness; in valleys they feel closed in; and one has told me that he thought few seeing people could enjoy the view from a mountain-top more than he. A blind person on entering a house or room immediately receives, from the reverberations of his voice and steps, an impression of its dimensions, and to a certain extent of its arrangement. The tympanic sense noticed on p. 140, _supra_, comes in to help here, and possibly other forms of tactile sensibility not yet understood. Mr. W. Hanks Levy, the blind author of 'Blindness and the Blind' (London), gives the following account of his powers of perception:

"Whether within a house or in the open air, whether walking or
standing still, I can tell, although quite blind, when I am opposite
an object, and can perceive whether it be tall or short, slender
or bulky. I can also detect whether it be a solitary object or a
continuous fence; whether it be a close fence or composed of open
rails; and often whether it be a wooden fence, a brick or stone wall,
or a quick-set hedge. I cannot usually perceive objects if much lower
than my shoulder, but sometimes very low objects can be detected.
This may depend on the nature of the objects, or on some abnormal
state of the atmosphere. The currents of air can have nothing to do
with this power, as the state of the wind does not directly affect
it; the sense of hearing has nothing to do with it, as when snow
lies thickly on the ground objects are more distinct, although the
footfall cannot be heard. I seem to perceive objects through the skin
of my face, and to have the impressions immediately transmitted to
the brain. The only part of my body possessing this power is my face;
this I have ascertained by suitable experiments. Stopping my ears
does not interfere with it, but covering my face with a thick veil
destroys it altogether. None of the five senses have anything to do
with the existence of this power, and the circumstances above named
induce me to call this unrecognized sense by the name of 'facial
perception.'... When passing along a street I can distinguish shops
from private houses, and even point out the doors and windows, etc.,
and this whether the doors be shut or open. When a window consists
of one entire sheet of glass, it is more difficult to discover than
one composed of a number of small panes. From this it would appear
that glass is a bad conductor of sensation, or at any rate of the
sensation specially connected with this sense. When objects below the
face are perceived, the sensation seems to come in an oblique line
from the object to the upper part of the face. While walking with a
friend in Forest Lane, Stratford, I said, pointing to a fence which
separated the road from a field, 'Those rails are not quite as high
as my shoulder.' He looked at them, and said they were higher. We,
however, measured, and found them about three inches lower than my
shoulder. At the time of making this observation I was about four feet
from the rails. Certainly in this instance facial perception was more
accurate than sight. When the lower part of a fence is brickwork, and
the upper part rails, the fact can be detected, and the line where the
two meet easily perceived. Irregularities in height, and projections
and indentations in walls, can also be discovered."

According to Mr. Levy, this power of seeing with the face is diminished by a fog, but not by ordinary darkness. At one time he could tell when a cloud obscured the horizon, but he has now lost that power, which he has known several persons to possess who are totally blind. These effects of aqueous vapor suggest immediately that fluctuations in the heat radiated by the objects may be the source of the perception. One blind gentleman, Mr. Kilburne, an instructor in the Perkins Institution in South Boston, who has the power spoken of in an unusual degree, proved, however, to have no more delicate a sense of temperature in his face than ordinary persons. He himself supposed that his ears had nothing to do with the faculty until a complete stoppage of them, not only with cotton but with putty on top of it, by abolishing the perception entirely, proved his first impression to be erroneous. Many blind men say immediately that their ears are concerned in the matter.

Sounds certainly play a far more prominent part in the mental life of the blind than in our own. In taking a walk through the country, the mutations of sound, far and near, constitute their chief delight. And to a great extent their imagination of distance and of objects moving from one distant spot to another seems to consist in thinking how a certain sonority would be modified by the change of place. It is unquestionable that the semi-circular-canal feelings play a great part in defining the points of the compass and the direction of distant spots, in the blind as in us. We _start_ towards them by feelings of this sort; and so many directions, so many different-feeling starts.[205]

The only point that offers any theoretic difficulty is the prolongation into space of the direction, after the start. We saw, ten pages back, that for extradition to occur beyond the skin, the portion of skin in question _and_ the space beyond must form a common object for some other sensory surface. The eyes are for most of us this sensory surface; for the blind it can only be other parts of the skin, coupled or not with motion. But the mere gropings of the hands in every direction must end by surrounding the whole body with a sphere of felt space. And this sphere must become enlarged with every movement of locomotion, these movements gaining their space-values from the semi-circular-canal feelings which accompany them, and from the farther and farther parts of large fixed objects (such as the bed, the wainscoting, or a fence) which they bring within the grasp. It might be supposed that a knowledge of space acquired by so many successive discrete acts would always retain a somewhat jointed and so to speak, granulated character. When we who are gifted with sight think of a space too large to come into a single field of view, we are apt to imagine it as composite, and filled with more or less jerky stoppings and startings (think, for instance, of the space from here to San Francisco), or else we reduce the scale symbolically and imagine how much larger on a map the distance would look than others with whose totality we are familiar.

I am disposed to believe, after interrogating many blind persons, that the use of imaginary maps on a reduced scale is less frequent with them than with the rest of us. Possibly the extraordinary changeableness of the visual magnitudes of things makes this habit natural to us, while the fixity of tactile magnitudes keeps them from falling into it. (When the blind young man operated on by Dr. Franz was shown a portrait in a locket, he was vastly surprised that the face could be put into so small a compass: it would have seemed to him, he said, as impossible as to put a bushel into a pint.) Be this as it may, however, the space which each blind man feels to extend beyond his body is felt by him as one smooth continuum--all trace of those muscular startings and stoppings and reversals which presided over its formation having been eliminated from the memory. It seems, in other words, a generic image of the space-element common to all these experiences, with the unessential particularities of each left out. In truth, _where_ in this space a start or a stop may have occurred was quite accidental. It may never occur just there again, and so the attention lets it drops altogether. Even as long a space as that traversed in a several-mile walk will not necessarily appear to a blind man's thought in the guise of a series of locomotor acts. Only where there is some distinct locomotor difficulty, such as a step to ascend, a difficult crossing, or a disappearance of the path, will distinct locomotor images constitute the idea. Elsewhere the space seems continuous, and its parts may even all seem coexistent; though, as a very intelligent blind friend once remarked to me, 'To think of such distances involves probably more mental wear and tear and brain-waste in the blind than in the seeing.' This seems to point to a greater element of successive addition and construction in the blind man's idea.

Our own visual explorations go on by means of innumerable stoppings and startings of the eyeballs. Yet these are all effaced from the final space-sphere of our visual imagination. They have neutralized each other. We can even distribute our attention to the right and left sides simultaneously, and think of those two quarters of space as coexistent. Does the smoothing out of the locomotor interruptions from the blind man's tactile space-sphere offer any greater paradox? Surely not. And it is curious to note that both in him and in us there is one particular locomotor feeling that is apt to assert itself obstinately to the last. We and he alike spontaneously imagine space as lying _in front_ of us, for reasons too obvious to enumerate. If we think of the space behind us, we, as a rule, have to _turn round_ mentally, and in doing so the front space vanishes. But in this, as in the other things of which we have been talking, individuals differ widely. Some, in imagining a room, can think of all its six surfaces at once. Others mentally turn round, or, at least, imagine the room in several successive and mutually exclusive acts (cf. p. 54, above).

      *       *       *       *       *

Sir William Hamilton, and J. S. Mill after him, have quoted approvingly an opinion of Platner (an eighteenth-century philosopher) regarding the space-perceptions of the blind. Platner says:

"The attentive observation of a person born blind... has convinced
me that the sense of touch by itself is altogether incompetent to
afford us the representation of extension and space.... In fact, to
those born blind, time serves instead of space. Vicinity and distance
mean in their mouths nothing more than the shorter or longer time ...
necessary to attain from some one feeling to some other."

After my own observation of blind people, I should hardly have considered this as anything but an eccentric opinion, worthy to pair off with that other belief that color is primitively seen without extent, had it not been for the remarkable Essay on Tactile and Visual Space by M. Ch. Dunan, which appeared in the Revue Philosophique for 1888. This author quotes[206] three very competent witnesses, all officials in institutions for the blind [it does not appear from the text that more than one of them was blind himself], who say that blind people _only live in time_. M. Dunan himself does not share exactly this belief, but he insists that the blind man's and the seeing man's representation of space have _absolutely naught_ in common, and that we are deceived into believing that what they mean by space is analogous to what we mean, by the fact that so many of them are but semi-blind and still think in visual terms, and from the farther fact that they all _talk_ in visual terms just like ourselves. But on examining M. Dunan's reasons one finds that they all rest on the groundless logical assumption that the perception of a geometrical form which we get with our eyes, and that which a blind man gets with his fingers, must either be absolutely identical or absolutely unlike. They cannot be similar in diversity, "for they are simple notions, and it is of the essence of such to enter the mind or leave it all at once, so that one who has a simple notion at all, possesses it in all its completeness.... Therefore, since it is impossible that the blind should have of the forms in question ideas _completely identical_ with our seeing ones, it follows that their ideas must be _radically different from and wholly irreducible to our own_."[207] Hereupon M. Dunan has no difficulty in finding a blind man who still preserves a crude sensation of diffused light, and who says when questioned that _this light has no extent_. Having 'no extent' appears, however, on farther questioning, to signify merely not enveloping any particular tactile objects, nor being located within their outline; so that (allowing for latitude of expression) the result tallies perfectly with our own view. A relatively stagnant retinal sensation of diffused light, not varying when different objects are handled, would naturally remain an object quite apart. If the word 'extent' were habitually used to denote tactile extent, this sensation, having no tactile associates whatever, would naturally have 'extent' denied of it. And yet all the while it would be _analogous_ to the tactile sensations in having the quality of bigness. Of course it would have no _other_ tactile qualities, just as the tactile objects have no other optical qualities than bigness. All sorts of analogies obtain between the spheres of sensibility. Why are 'sweet' and 'soft' used so synonymously in most languages? and why are both these adjectives applied to objects of so many sensible kinds? Rough sounds, heavy smells, hard lights, cold colors, are other examples. Nor does it follow from such analogies as these that the sensations compared need be composite and have some of their parts identical. We saw in Chapter XIII that likeness and difference are an elementary relation, not to be resolved in every case into a mixture of absolute identity and absolute heterogeneity of content (cf. Vol. I, pp. 492-3).

I conclude, then, that although in its more superficial determinations the blind man's space is very different from our space, yet a deep analogy remains between the two. 'Big' and 'little,' 'far' and 'near,' are similar contents of consciousness in both of us. But the _measure_ of the bigness and the farness is very different in him and in ourselves. He, for example, can have no notion of what we mean by objects appearing smaller as they move away, because he must always conceive of them as of their constant tactile size. Nor, whatever analogy the two extensions involve, should we expect that a blind man receiving sight for the first time should recognize his new-given optical objects by their familiar tactile names. Molyneux wrote to Locke:

"Suppose a man born blind, and now adult, and taught by his touch to
distinguish between a cube and a sphere,... so as to tell, when he
felt one and the other, which is the cube, which the sphere. Suppose
then the cube and sphere placed on a table and the blind man to be
made to see; query, whether by his sight, before he touched them, he
could now distinguish and tell which is the globe, which the cube?"

This has remained in literature as 'Molyneux's query.' Molyneux answered 'No.' And Locke says:[208]

"I agree with this thinking gentleman whom I am proud to call my
friend, and am of opinion that the blind man at first sight would not
be able to say which was the globe, which the cube, whilst he only saw
them; though he could unerringly name them by his touch and certainly
distinguish them by the difference of their figures felt."

This opinion has not lacked experimental confirmation. From Chesselden's case downwards, patients operated for congenital cataract have been unable to name at first the things they saw. "So, Puss, I shall know you another time," said Chesselden's patient, after catching the cat, looking at her steadfastly, and setting her down. Some of this incapacity is unquestionably due to general mental confusion at the new experience, and to the excessively unfavorable conditions for perception which an eye with its lens just extirpated affords. That the analogy of inner nature between the retinal and tactile sensations goes beyond mere extensity is proved by the cases where the patients were the most intelligent, as in the young man operated on by Dr. Franz, who named circular, triangular, and quadrangular figures at first sight.[209]


VISUAL SPACE.


It is when we come to analyze minutely the conditions of _visual_ perception that difficulties arise which have made psychologists appeal to new and _quasi_-mythical mental powers. But I firmly believe that even here exact investigation will yield the same verdict as in the cases studied hitherto. This subject will close our survey of the facts; and if it give the result I foretell, we shall be in the best of positions for a few final pages of critically historical review.

If a common person is asked how he is enabled to see things as they are, he will simply reply, by opening his eyes and looking. This innocent answer has, however, long since been impossible for science. There are various paradoxes and irregularities about _what_ we appear to perceive under seemingly identical optical conditions, which immediately raise questions. To say nothing now of the time-honored conundrums of why we see upright with an inverted retinal picture, and why we do not see double; and to leave aside the whole field of color-contrasts and ambiguities, as not directly relevant to the space-problem,--it is certain that the same retinal image makes us see quite differently-sized and differently-shaped objects at different times, and it is equally certain that the same ocular movement varies in its perceptive import. It ought to be possible, were the act of perception completely and _simply_ intelligible, to assign for every distinct judgment of size, shape, and position a distinct optical modification of some kind as its occasion. And the connection between the two ought to be so constant that, given the same modification, we should always have the same judgment. But if we study the facts closely _we soon find no such constant connection between either judgment and retinal modification, or judgment and muscular modification, to exist._ The judgment seems to result from the combination of retinal, muscular and intellectual factors with each other; and any one of them may occasionally overpower the rest in a way which seems to leave the matter subject to no simple law.

The scientific study of the subject, if we omit Descartes, began with Berkeley, and the particular perception he analyzed in his New Theory of Vision was that of distance or depth. Starting with the physical assumption that a difference in the distance of a point can make no difference in the nature of its retinal image, since "distance being a line directed endwise to the eye, it projects only one point in the fund of the eye--which point remains invariably the same, whether the distance be longer or shorter," he concluded that distance could not possibly be a visual sensation, but must be an intellectual 'suggestion' from 'custom' of some non-visual experience. According to Berkeley this experience was tactile. His whole treatment of the subject was excessively vague,--no shame to him, as a breaker of fresh ground,--but as it has been adopted and enthusiastically hugged in all its vagueness by nearly the whole line of British psychologists who have succeeded him, it will be well for us to begin our study of vision by refuting his notion that depth cannot possibly be perceived in terms of purely visual feeling.


_The Third Dimension._


Berkeleyans unanimously assume that no retinal sensation can primitively be of volume; if it be of extension at all (which they are barely disposed to admit), it can be only of two-, not of three-, dimensional extension. At the beginning of the present chapter we denied this, and adduced facts to show that all objects of sensation are voluminous in three dimensions (cf. p. 136 ff.). It is impossible to lie on one's back on a hill, to let the empty abyss of blue fill one's whole visual field, and to sink deeper and deeper into the merely sensational mode of consciousness regarding it, without feeling that an indeterminate, palpitating, circling depth is as indefeasibly one of its attributes as its breadth. We may artificially exaggerate this sensation of depth. Rise and look from the hill-top at the distant view; represent to yourself as vividly as possible the distance of the uttermost horizon; and then _with inverted head_ look at the same. There will be a startling increase in the perspective, a most sensible recession of the maximum distance; and as you raise the head you can actually see the horizon-line again draw near.[210]

Mind, I say nothing as yet about our estimate of the 'real' amount of this depth or distance. I only want to confirm its existence as a natural and inevitable optical consort of the two other optical dimensions. The field of view is always a _volume-unit_. Whatever be supposed to be its absolute and 'real' size, the relative sizes of its dimensions are functions of each other. Indeed, it happens perhaps most often that the breadth- and height-feeling take their absolute measure from the depth-feeling. If we plunge our head into a wash-basin, the felt nearness of the bottom makes us feel the lateral expanse to be small. If, on the contrary, we are on a mountain-top, the distance of the horizon carries with it in our judgment a proportionate height and length in the mountain-chains that bound it to our view. But as aforesaid, let us not consider the question of absolute size now,--it must later be taken up in a thorough way. Let us confine ourselves to the way in which the three dimensions which are seen, get their values fixed _relatively to each other_.

Reid, in his Inquiry into the Human Mind, has a section 'Of the Geometry of Visibles,' in which he assumes to trace what the perceptions would be of a race of 'Idomenians' reduced to the sole sense of sight. Agreeing with Berkeley that sight alone can give no knowledge of the third dimension, he humorously deduces various ingenious absurdities in their interpretations of the material appearances before their eyes.

Now I firmly believe, on the contrary, that one of Reid's Idomenians would frame precisely the same conception of the external world that we do, if he had our intellectual powers.[211] Even were his very eyeballs fixed and not movable like ours, that would only retard, not frustrate, his education. For the _same object_, by alternately covering in its lateral movements different parts of his retina, would determine the mutual equivalencies of the first two dimensions of the field of view; and by exciting the physiological cause of his perception of depth in various degrees, it would establish a scale of equivalency between the first two and the third.

First of all, one of the sensations given by the object is chosen to represent its 'real' size and shape, in accordance with the principles laid down on pp. 178 and 179. _One sensation measures the 'thing' present, and the 'thing' then measures the other sensations._ The peripheral parts of the retina are equated with the central by receiving the image of the same object. This needs no elucidation in case the object does not change its distance or its front. But suppose, to take a more complicated case, that the object is a stick, seen first in its whole length, and then rotated round one of its ends; let this fixed end be the one near the eye. In this movement the stick's image will grow progressively shorter; its farther end will appear less and less separated laterally from its fixed near end; soon it will be screened by the latter, and then reappear on the opposite side, and finally on that side resume its original length. Suppose this movement to become a familiar experience; the mind will presumably react upon it after its usual fashion (which is that of unifying all data which it is in any way possible to unify), and consider it the movement of a constant object rather than the transformation of a fluctuating one. Now, the _sensation of depth_ which it receives during the experience is awakened more by the far than by the near end of the object. But how much depth? What shall measure its amount? Why, at the moment the far end is ready to be eclipsed, the difference of its distance from the near end's distance must be judged equal to the stick's whole length; but that length has already been judged equal to a certain optical sensation of breadth. _Thus we find that given amounts of the visual depth-feeling become signs of fixed amounts of the visual breadth-feeling. The measurement of distance is, as Berkeley truly said, a result of suggestion and experience. But visual experience alone is adequate to produce it, and this he erroneously denied._

Suppose a colonel in front of his regiment at dress-parade, and suppose he walks at right angles towards the midmost man of the line. As he advances, and surveys the line in either direction, he looks more and more _down_ it and less and less _at_ it, until, when abreast of the midmost man, he feels the end men to be _most_ distant; then when the line casts hardly any lateral image on his retina at all, what distance shall he judge to be that of the end men? Why, half the length of the regiment as it was originally seen, of course; but this length was a moment ago a retinal object spread out laterally before his sight. He has now merely equated a retinal depth-feeling with a retinal breadth-feeling. If the regiment moved, and the colonel stood still, the result would be the same. In such ways as these a creature endowed with eyes alone could hardly fail of measuring out all three dimensions of the space he inhabited. And we ourselves, I think, although we _may_ often 'realize' distance in locomotor terms (as Berkeley says we must always do), yet do so no less often in terms of our retinal map, and always in this way the more spontaneously. Were this not so, the three visual dimensions could not possibly feel to us as homogeneous as they do, nor as commensurable _inter se_.

_Let us then admit distance to be at least as genuinely optical a content of consciousness as either height or breadth. The question immediately returns, Can any of them be said in any strictness to be optical sensations?_ We have contended all along for the affirmative reply to this question, but must now cope with difficulties greater than any that have assailed us hitherto.


_Helmholtz and Reid on Sensations_.


A sensation is, as we have seen in Chapter XVII, the mental affection that follows most immediately upon the stimulation of the sense-tract. Its antecedent is directly physical, no psychic links, no acts of memory, inference, or association intervening. Accordingly, if we suppose the nexus between neural process in the sense-organ, on the one hand, and conscious affection, on the other, to be by nature uniform, _the same process ought always to give the same sensation;_ and conversely, _if what seems to be a sensation varies whilst the process in the sense-organ remains unchanged, the reason is presumably that it is really not a sensation but a higher mental product, whereof the variations depend on events occurring in the system of higher cerebral centres._

Now the _size_ of the field of view varies enormously in all three dimensions, without our being able to assign with any definiteness the process in the visual tract on which the variation depends. We just saw how impossible such assignment was in the case where turning down the head produces the enlargement. In general, the maximum feeling of depth or distance seems to take the lead in determining the apparent magnitude of the whole field, and the two other dimensions seem to follow. If, to use the former instance, I look close into a wash-basin, the lateral extent of the field shrinks proportionately to its nearness. If I look from a mountain, the things seen are vast in height and breadth, in proportion to the farness of the horizon. But _when we ask what changes in the eye determine how great this maximum feeling of depth or distance_ (which is undoubtedly felt as a unitary vastness) _shall be, we find ourselves unable to point to any one of them as being its absolutely regular concomitant._ Convergence, accommodation, double and disparate images, differences in the parallactic displacement when we move our head, faintness of tint, dimness of outline, and smallness of the retinal image of objects named and known, are all processes that have _something to do_ with the perception of 'far' and of 'near'; but the effect of each and any one of them in determining such a perception at one moment may at another moment be reversed by the presence of some other sensible quality in the object, that makes us, evidently by reminding us of past experience, judge it to be at a different distance and of another shape. If we paint the inside of a pasteboard-mask like the outside, and look at it with one eye, the accommodation- and parallax-feelings are there, but fail to make us see it hollow, as it is. Our mental knowledge of the fact that human faces are always convex overpowers them, and we directly perceive the nose to be nearer to us than the cheek instead of farther of.

The other organic tokens of farness and nearness are proved by similar experiments (of which we shall ere long speak more in detail) to have an equally fluctuating import. They lose all their value whenever the collateral circumstances favor a strong intellectual conviction that the object presented to the gaze is _improbable_--cannot be either _what_ or _where_ they would make us perceive it to be.

Now the query immediately arises: _Can the feelings of these processes in the eye, since they are so easily neutralized and reversed by intellectual suggestions, ever have been direct sensations of distance at all_? Ought we not rather to assume, since the distances which we see _in spite_ of them are conclusions from past experience, that the distances which we see _by means_ of them are equally such conclusions? Ought we not, in short, to say unhesitatingly that distance must be an intellectual and not a sensible content of consciousness? and that each of these eye-feelings serves as a mere signal to awaken this content, our intellect being so framed that sometimes it notices one signal more readily and sometimes another?

Reid long ago (Inquiry, c. vi. sec. 17) said:

"It may be taken for a general rule that things which are produced by
custom may be undone or changed by disuse or by contrary custom. On
the other hand, it is a strong argument that an effect is not owing to
custom, but to the constitution of nature, when a contrary custom is
found neither to change nor to weaken it."

More briefly, a way of seeing things that can be unlearned was presumably learned, and only what we cannot unlearn is instinctive.

This seems to be Helmholtz's view, for he confirms Reid's maxim by saying in emphatic print:

"No elements in our perception can be sensational which may be
overcome or reversed by factors of demonstrably experimental origin.
Whatever can be overcome by suggestions of experience must be regarded
as itself a product of experience and custom. If we follow this rule
it will appear that only _qualities_ are sensational, whilst almost
all _spatial_ attributes are results of habit and experience."[212]

This passage of Helmholtz's has obtained, it seems to me, an almost deplorable celebrity. The reader will please observe its very radical import. Not only would he, and does he, for the reasons we have just been ourselves considering, deny distance to be an optical sensation; but, extending the same method of criticism to judgments of size, shape, and direction, and finding no single retinal or muscular process in the eyes to be indissolubly linked with any one of these, he goes so far as to say that all optical space-perceptions whatsoever must have an intellectual origin, and a content that no items of visual sensibility can account for.[213]

As Wundt and others agree with Helmholtz here, and as their conclusions, if true, are irreconcilable with all the sensationalism which I have been teaching hitherto, it clearly devolves upon me to defend my position against this new attack. But as this chapter on Space is already so overgrown with episodes and details, I think it best to reserve the refutation of their general principle for the next chapter, and simply to assume at this point its untenability. This has of course an arrogant look; but if the reader will bear with me for not very many pages more, I shall hope to appease his mind. Meanwhile I affirm confidently that _the same outer objects actually_ FEEL _different to us according as our brain reacts on them in one way or another by making us perceive them as this or as that sort of thing._ So true is this that one may well, with Stumpf,[214] reverse Helmholtz's query, and ask: "What would become of our sense-perceptions in case experience were _not_ able so to transform them?" Stumpf adds: "All wrong perceptions that depend on peculiarities in the organs are more or less perfectly corrected by the influence of imagination following the guidance of experience."

If, therefore, among the facts of optical space-perception (which we must now proceed to consider in more detail) we find instances of an identical organic eye-process, giving us different perceptions at different times, in consequence of different collateral circumstances suggesting different objective facts to our imagination, we must not hastily conclude, with the school of Helmholtz and Wundt, that the organic eye-process pure and simple, without the collateral circumstances, is incapable of giving us any sensation of a spatial kind at all. We must rather seek to discover _by what means_ the circumstances can so have transformed a space-sensation, which, but for their presence, would probably have been felt in its natural purity. And I may as well say now in advance that we shall find the means to be nothing more or less than association--_the suggestion to the mind of optical objects not actually present,_ but more habitually associated with the 'collateral circumstances' than the sensation which they now displace and being imagined now with a quasi-hallucinatory strength. But before this conclusion emerges, it will be necessary to have reviewed the most important facts of optical space-perception, in relation to the organic conditions on which they depend. Readers acquainted with German optics will excuse what is already familiar to them in the following section.[215]

Let us begin the long and rather tedious inquiry by the most important case. Physiologists have long sought for a simple law by which to connect the seen direction and distance of objects with the retinal impressions they produce. Two principal theories have been held of this matter, the 'theory of identical points,' and the 'theory of projection,'--each incompatible with the other, and each beyond certain limits becoming inconsistent with the facts.


_The Theory of Identical Points_.


[Illustration: FIG. 54.]

This theory starts from the truth that on both retinæ an impression on the upper half makes us perceive an object as below, on the lower half as above, the horizon; and on the right half an object to the left, on the left half one to the right, of the median line. Thus each quadrant of one retina corresponds as a whole to the _similar_ quadrant of the other; and within two similar quadrants, _al_ and _ar_ for example, there should, if the correspondence were consistently carried out, be geometrically similar points which, if impressed at the same time by light emitted from the same object, should cause that object to appear in the same direction to either eye. Experiment verifies this surmise. If we look at the starry vault with parallel eyes, the stars all seem single; and the laws of perspective show that under the circumstances the parallel light-rays coming from each star must impinge on points within either retina which _are_ geometrically similar to each other. The same result may be more artificially obtained. If we take two exactly similar pictures, smaller, or at least no larger, than those on an ordinary stereoscopic slide, and if we look at them as stereoscopic slides are looked at, that is, at one with each eye (a median partition confining the view of either eye to the picture opposite it), we shall see but one flat picture, all of whose parts appear sharp and single.[216] Identical points being impressed, both eyes see their object in the same direction, and the two objects consequently coalesce into one.

The same thing may be shown in still another way. With fixed head converge the eyes upon some conspicuous objective point behind a pane of glass; then close either eye alternately and make a little ink-mark on the glass, 'covering' the object as seen by the eye which is momentarily open. On looking now with both eyes the ink-marks will seem single, and in the same direction as the objective point. Conversely, let the eyes converge on a single ink-spot on the glass, and then by alternate shutting of them let it be noted what objects behind the glass the spot covers to the right and left eye respectively. Now with both eyes open, both these objects and the spot will appear in the same place, one or other of the three becoming more distinct according to the fluctuations of retinal attention.[217]

Now what is the direction of this common place? The only way of defining the direction of an object is by _pointing to it_. Most people, if asked to look at an object over the horizontal edge of a sheet of paper which conceals their hand and arm, and then to point their finger at it (raising the hand gradually so that at last a finger-tip will appear above the sheet of paper), are found to place the finger not between either eye and the object, but between the latter and the root of the nose, and this whether both eyes or either alone be used. Hering and Helmholtz express this by saying that we judge of the direction of objects as they would appear to an imaginary cyclopean eye, situated between our two real eyes, and with its optical axis bisecting the angle of convergence of the latter. Our two retinæ act, according to Hering, as if they were superposed in the place of this imaginary double-eye; we see by the corresponding points of each, situated far asunder as they really are, just as we _should_ see if they were superposed and could both be excited together.

The judgment of objective singleness and that of identical direction seem to hang necessarily together. And that of identical direction seems to carry with it the necessity of a common origin, between the eyes or elsewhere, from which all the directions felt may seem to be estimated. This is why the cyclopean eye is really a fundamental part of the formulation of the theory of identical retinal points, and why Hering, the greatest champion of this theory, lays so much stress upon it.

_It is an immediate consequence of the law of identical_ _projection of images on geometrically similar points that images which fall upon geometrically_ DISPARATE _points of the two retinæ should be projected in_ DISPARATE _directions, and that their objects should consequently appear in_ TWO _places, or_ LOOK DOUBLE. Take the parallel rays from a star falling upon two eyes which converge upon a near object, O, instead of being parallel, as in the previously instanced case. If SL and SR in Fig. 55 be the parallel rays, each of them will fall upon the nasal half of the retina which it strikes.

[Illustration: FIG. 55.]

But the two nasal halves are disparate, geometrically _symmetrical_, not geometrically _similar_. The image on the left one will therefore appear as if lying in a direction leftward of the cyclopean eye's line of sight; the image of the right one will appear far to the right of the same direction. The star will, in short, be seen double,--'homonymously' double.

Conversely, if the star be looked at directly with parallel axes, O will be seen double, because its images will affect the outer or cheek halves of the two retinæ, instead of one outer and one nasal half. The position of the images will here be reversed from that of the previous case. The right eye's image will now appear to the left, the left eye's to the right--the double images will be 'heteronymous.'

The same reasoning and the same result ought to apply where the object's place with respect to the direction of the two optic axes is such as to make its images fall not on non-similar retinal halves, but on non-similar parts of similar halves. Here, of course, the directions of projection will be less widely disparate than in the other case, and the double images will appear to lie less widely apart.

Careful experiments made by many observers according to the so-called haploscopic method confirm this law, and show that _corresponding points, of single visual direction,_ exist upon the two retinæ. For the detail of these one must consult the special treatises.

Note now an important consequence. If we take a stationary object and allow the eyes to vary their direction and convergence, a purely geometrical study will show that there will be some positions in which its two images impress corresponding retinal points, but more in which they impress disparate points. The former constitute the so-called horopter, and their discovery has been attended with great mathematical difficulty. Objects or parts of objects which lie in the eyes' horopter at any given time cannot appear double. _Objects lying out of the horopter would seem, if the theory of identical points were strictly true, necessarily and always to appear double._

Here comes the first great conflict of the identity-theory with experience. Were the theory true, we ought all to have an intuitive knowledge of the horopter as the line of distinctest vision. Objects placed elsewhere ought to seem, if not actually double, at least blurred. And yet no living man makes any such distinction between the parts of his field of vision. To most of us the whole field appears single, and it is only by rare accident or by special education that we ever catch a glimpse of a double image. In 1838, Wheatstone, in his truly classical memoir on binocular vision and the stereoscope,[218] showed that the disparateness of the points on which the two images of an object fall does not within certain limits affect its seen singleness at all, but rather the _distance_ at which it shall appear. Wheatstone made an observation, moreover, which subsequently became the bone of much hot contention, in which he strove to show that not only might disparate images fuse, but images on corresponding or identical points might be seen double.[219]

I am unfortunately prevented by the weakness of my own eyes from experimenting enough to form a decided personal opinion on the matter. It seems to me, however, that the balance of evidence is against the Wheatstonian interpretation, and that disparate points may fuse, without identical points for that reason ever giving double images. The two questions, "Can we see single with disparate points?" and "Can we see double with identical points?" although at the first blush they may appear, as to Helmholtz they appear, to be but two modes of expressing the same inquiry, are in reality distinct. The first may quite well be answered affirmatively and the second negatively.

Add to this that the experiment quoted from Helmholtz above by no means always succeeds, but that many individuals place their finger between the object and _one_ of their eyes, oftenest the right;[220] finally, observe that the identity-theory, with its Cyclopean starting point for all lines of direction, gives by itself no ground for the _distance_ on any line at which an object shall appear, and has to be helped out in this respect by subsidiary hypotheses, which, in the hands of Hering and others, have become so complex as easily to fall a prey to critical attacks; and it will soon seem as if _the law of identical seen directions by corresponding points, although a simple formula for expressing concisely many fundamental phenomena, is by no means an adequate account of the whole matter of retinal perception._[221]


_The Projection-Theory_.


Does the theory of projection fare any better? This theory admits that each eye sees the object in a different direction from the other, along the line, namely, passing from the object through the middle of the pupil to the retina. A point directly fixated is thus seen on the optical axes of both eyes. There is only one point, however, which these two optical axes have in common, and that is the point to which they converge. Everything directly looked at is seen at this point, and is thus seen both single and at its proper distance. It is easy to show the incompatibility of this theory with the theory of identity. Take an objective point (like O in Fig. 50, when the star is looked at) casting its images R' and L' on geometrically dissimilar parts of the two retinæ and affecting the outer half of each eye. On the identity-theory it ought necessarily to appear double, whilst on the projection-theory there is no reason whatever why it should not appear single, provided only it be located by the judgment on each line of visible direction, neither nearer nor farther than its point of intersection with the other line.

_Every point in the field of view ought, in truth, if the projection-theory were uniformly valid, to appear single,_ entirely irrespective of the varying positions of the eyes, for from every point of space two lines of visible direction pass to the two retinæ; and at the intersection of these lines, or just where the point is, there, according to the theory, it should appear. _The objection to this theory is thus precisely the reverse of the objection to the identity-theory. If the latter ruled, we ought to see most things double all the time. If the projection-theory ruled, we ought never to see anything double. As a matter of fact we get too few double images for the identity-theory, and too many for the projection-theory._

The partisans of the projection-theory, beginning with Aguilonius, have always explained double images as the result of an erroneous judgment of the _distance_ of the object, the images of the latter being projected by the imagination along the two lines of visible direction either nearer or farther than the point of intersection of the latter. A diagram will make this clear.

[Illustration: FIG. 56.]

Let O be the point looked at, M an object farther, and N an object nearer, than it. Then M and N will send the lines of visible direction MM and NN to the two retinæ. If N be judged as far as O, it must necessarily lie where the two lines of visible direction NN intersect the plane of the arrow, or in two places, at N' and at N. If M be judged as near as O, it must for the same reason form two images at M' and M.

It is, as a matter of fact, true that we often misjudge the distance in the way alleged. If the reader will hold his forefingers, one beyond the other, in the median line, and fixate them alternately, he will see the one not looked at, double; and he will also notice that it appears nearer to the plane of the one looked at, whichever the latter may be, than it really is. Its changes of apparent size, as the convergence of the eyes alter, also prove the change of apparent distance. The distance at which the axes converge seems, in fact, to exert a sort of attraction upon objects situated elsewhere. Being the distance of which we are most acutely sensible, it invades, so to speak, the whole field of our perception. If two half-dollars be laid on the table an inch or two apart, and the eyes fixate steadily the point of a pen held in the median line at varying distances between the coins and the face, there will come a distance at which the pen stands between the left half-dollar and the right eye, and the right half-dollar and the left eye. The two half-dollars will then coalesce into one; and this one will show its apparent approach to the pen-point by seeming suddenly much reduced in size.[222]

Yet, in spite of this tendency to inaccuracy, we are never actually mistaken about the half-dollar being behind the pen-point. It may not seem far enough off, but still it is farther than the point. In general it may be said that where the objects are known to us, no such illusion of distance occurs in any one as the theory would require. And in some observers, Hering for example, it seems hardly to occur at all. If I look into infinite distance and get my finger in double images, they do not seem infinitely far off. To make objects at different distances seem equidistant, careful precautions must be taken to have them alike in appearance, and to exclude all outward reasons for ascribing to the one a different location from that ascribed to the other. Thus Donders tries to prove the law of projection by taking two similar electric sparks, one behind the other on a dark ground, one seen double; or an iron rod placed so near to the eyes that its double images seem as broad as that of a fixated stove-pipe, the top and bottom of the objects being cut off by screens, so as to prevent all suggestions of perspective, etc. The three objects in each experiment seem in the same plane.[223]

Add to this the impossibility, recognized by _all_ observers, of ever seeing double with the _fovea_, and the fact that authorities as able as those quoted in the note on Wheatstone's observation deny that they can see double then with identical points, and we are forced to conclude that _the projection-theory, like its predecessor, breaks down. Neither formulates exactly or exhaustively a law for all our perceptions._


_Ambiguity of Retinal Impressions_.


[Illustration: FIG. 57.]

_What does each theory try to do? To make of seen location a fixed function of retinal impression. Other facts may be brought forward to show how far from fixed are the perceptive functions of retinal impressions._ We alluded a while ago to the extraordinary ambiguity of the retinal image as a revealer of magnitude. Produce an after-image of the sun and look at your finger-tip: it will be smaller than your nail. Project it on the table, and it will be as big as a strawberry; on the wall, as large as a plate; on yonder mountain, bigger than a house. And yet it is an unchanged retinal impression. Prepare a sheet with the figures shown in Fig. 57 strongly marked upon it, and get by direct fixation a distinct after-image of each.

[Illustration: FIGS. 58 & 59.]

Project the after-image of the cross upon the upper left-hand part of the wall, it will appear as in Fig. 58; on the upper right-hand it will appear as in Fig. 59. The circle similarly projected will be distorted into two different ellipses. If the two parallel lines be projected upon the ceiling or floor far in front, the farther ends will diverge; and if the three parallel lines be thrown on the same surfaces, the upper pair will seem farther apart than the lower.

[Illustration: FIG. 60.]

[Illustration: FIG. 61.]

Adding certain lines to others has the same distorting effect. In what is known as Zöllner's pattern (Fig. 60), the long parallels tip towards each other the moment we draw the short slanting lines over them yet their retinal images are the same they always were. A similar distortion of parallels appears in Fig 61.

[Illustration: FIG. 62.]

[Illustration: FIG. 63.]

Drawing a square inside the circle (Fig. 62) gives to the outline of the latter an indented appearance where the square's corners touch it. Drawing the radii inside of one of the right angles in the same figure makes it seem larger than the other. In Fig. 63, the retinal image of the space between the extreme dots is in all three lines the same, yet it seems much larger the moment it is filled up with other dots.

In the stereoscope certain pairs of lines which look single under ordinary circumstances immediately seem double when we add certain other lines to them.[224]

_Ambiguous Import of Eye-movements_.


These facts show the indeterminateness of the space-import of various _retinal impressions_. Take now the _eye's movements_, and we find a similar vacillation. When we follow a moving object with our gaze, the motion is 'voluntary'; when our eyes oscillate to and fro after we have made ourselves dizzy by spinning around, it is 'reflex'; and when the eyeball is pushed with the finger, it is 'passive.' Now, in all three of these cases we get a feeling from the movement as it effects itself. But the objective perceptions to which the feeling assists us are by no means the same. In the first case we may see a stationary field of view with one moving object in it; in the second, the total field swimming more or less steadily in one direction; in the third, a sudden jump or twist of the same total field.

_The feelings of convergence_ of the eyeballs permit of the same ambiguous interpretation. When objects are near we converge strongly upon them in order to see them; when far, we set our optic axes parallel. But the exact degree of convergence fails to be felt; or rather, being felt, fails to tell us the absolute distance of the object we are regarding. Wheatstone arranged his stereoscope in such a way that the size of the retinal images might change without the convergence altering; or conversely, the convergence might change without the retinal image altering. Under these circumstances, he says,[225] the object seemed to approach or recede in the first case, without altering its size, in the second, to change its size without altering its distance--just the reverse of what might have been expected. Wheatstone adds, however, that 'fixing the attention' converted each of these perceptions into its opposite. The same perplexity occurs in looking through prismatic glasses, which alter the eyes' convergence. We cannot decide whether the object has come nearer, or grown larger, or both, or neither; and our judgment vacillates in the most surprising way. We may even make our eyes diverge, and the object will none the less appear at a finite distance. When we look through the stereoscope, the picture seems at no determinate distance. These and other facts have led Helmholtz to deny that the feeling of convergence has any very exact value as a distance-measurer.[226]

With _the feelings of accommodation_ it is very much the same. Donders has shown[227] that the apparent magnifying power of spectacles of moderate convexity hardly depends at all upon their enlargement of the retinal image, but rather on the relaxation they permit of the muscle of accommodation. This suggests an object farther off, and consequently a much larger one, since its retinal size rather increases than diminishes. But in this case the same vacillation of judgment as in the previously mentioned case of convergence takes place. The recession made the object seem larger, but the apparent growth in size of the object now makes it look as if it came nearer instead of receding. The effect thus contradicts its own cause. Everyone is conscious, on first putting on a pair of spectacles, of a doubt whether the field of view draws near or retreats.[228]

There is still _another deception, occurring in persons who have had one eye-muscle suddenly paralyzed._ This deception has led Wundt to affirm that the eyeball-feeling proper, the incoming sensation of effected rotation, tells us only of the direction of our eye-movements, but not of their whole extent.[229] For this reason, and because not only Wundt, but many other authors, think the phenomena in these partial paralyses demonstrate the existence of a feeling of innervation, a feeling of the outgoing nervous current, opposed to every afferent sensation whatever, it seems proper to note the facts with a certain degree of detail.

Suppose a man wakes up some morning with the external rectus muscle of his right eye half paralyzed, what will be the result? He will be enabled only with great effort to rotate the eye so as to look at objects lying far off to the right. Something in the effort he makes will make him feel as if the object lay much farther to the right than it really is. If the left and sound eye be closed, and he be asked to touch rapidly with his finger an object situated towards his right, he will point the finger to the right of it. The current explanation of the 'something' in the effort which causes this deception is that it is the sensation of the outgoing discharge from the nervous centres, the 'feeling of innervation,' to use Wundt's expression, requisite for bringing the open eye with its weakened muscle to bear upon the object to be touched. If that object be situated 20 degrees to the right, the patient has now to innervate as powerfully to turn the eye those 20 degrees as formerly he did to turn the eye 30 degrees. He consequently believes as before that he _has_ turned it 30 degrees; until, by a newly-acquired custom, he learns the altered spatial import of all the discharges his brain makes into his right abducens nerve. The 'feeling of innervation,' maintained to exist by this and other observations, plays an immense part in the space-theories of certain philosophers, especially Wundt. I shall elsewhere try to show that the observations by no means warrant the conclusions drawn from them, and that the feeling in question is probably a wholly fictitious entity.[230] Meanwhile it suffices to point out that even those who set most store by it are compelled, by the readiness with which the translocation of the field of view becomes corrected and further errors avoided, to admit that the precise space-import of _the supposed sensation of outgoing energy is as ambiguous and indeterminate as that of any other of the eye-feelings we have considered hitherto._

      *       *       *       *       *

I have now given what no one will call an understatement of the facts and arguments by which it is sought to banish the credit of directly revealing space from each and every kind of eye-sensation taken by itself. The reader will confess that they make a very plausible show, and most likely wonder whether my own theory of the matter can rally from their damaging evidence. But the case is far from being hopeless; and the introduction of a discrimination hitherto unmade will, if I mistake not, easily vindicate the view adopted in these pages, whilst at the same time it makes ungrudging allowance for all the ambiguity and illusion on which so much stress is laid by the advocates of the intellectualist-theory.


_The Choice of the Visual Reality._


We _have_ native and fixed optical space-sensations; _but experience leads us to select certain ones from among them to be the exclusive bearers of reality: the rest become mere signs and suggesters of these._ The factor of _selection_, on which we have already laid so much stress, here as elsewhere is the solving word of the enigma. If Helmholtz, Wundt, and the rest, with an ambiguous retinal sensation before them, meaning now one size and distance, and now another, had not contented themselves with merely saying:--The size and distance are not this sensation, they are something beyond it which it merely calls up, and whose own birthplace is afar--in 'synthesis' (Wundt) or in 'experience' (Helmholtz) as the case may be; if they had gone on definitely to ask and definitely to answer the question, What are the size and distance in their proper selves? they would not only have escaped the present deplorable vagueness of their space-theories, but they would have seen that the objective spatial attributes 'signified' are simply and solely _certain other optical sensations now absent_, but which the present sensations suggest.

What, for example, is the slant-legged cross which we think we see on the wall when we project the rectangular after-image high up towards our right or left (Figs. 58 and 59)? Is it not in very sooth a retinal sensation itself? An imagined sensation, not a felt one, it is true, but none the less essentially and originally sensational or retinal for that,--the sensation, namely, which we should receive if a 'real' slant-legged cross stood on the wall _in front of us_ and threw its image on our eye. That image is not the one our retina now holds. Our retina now holds the image which a cross of square shape throws when in front, but which a cross of the slant-legged pattern _would_ throw, provided it were actually on the wall in the distant place at which we look. Call this actual retinal image the 'square' image. The square image is then one of the innumerable images the slant-legged cross can throw. Why should another one, and that an absent one, of those innumerable images be picked out to represent exclusively the slant-legged cross's 'true' shape? Why should that absent and imagined slant-legged image displace the present and felt square image from our mind? Why, when the objective cross gives us so many shapes, as it varies its position, should we think we feel the true shape only when the cross is directly in front? And when that question is answered, how can the absent and represented feeling of a slant-legged figure so successfully intrude itself into the place of a presented square one?

Before answering either question, let us be doubly sure about our facts, and see how true it is that _in our dealings with objects we always do pick out one of the visual images they yield, to constitute the real form or size._

The matter of size has been already touched upon, so that no more need be said of it here. As regards shape, almost all the retinal shapes that objects throw are perspective 'distortions.' Square table-tops constantly present two acute and two obtuse angles; circles drawn on our wall-papers, our carpets, or on sheets of paper, usually show like ellipses; parallels approach as they recede; human bodies are foreshortened; and the transitions from one to another of these altering forms are infinite and continual. Out of the flux, however, one phase always stands prominent. It is the form the object has when we see it easiest and best: and that is when our eyes and the object both are in what may be called _the normal position_. In this position our head is upright and our optic axes either parallel or symmetrically convergent; the plane of the object is perpendicular to the visual plane; and if the object is one containing many lines it is turned so as to make them, as far as possible, either parallel or perpendicular to the visual plane. In this situation it is that we compare all shapes with each other; here every exact measurement and decision is made.[231]

_It is very easy to see why the normal situation should have this extraordinary pre-eminence._ First, it is the position in which we easiest hold anything we are examining in our hands; second, it is a turning-point between all right- and all left-hand perspective views of a given object; third, it is the only position in which symmetrical figures seem symmetrical and equal angles seem equal; fourth, it is often that starting-point of movements from which the eye is least troubled by axial rotations, by which _superposition_[232] of the retinal images of different lines and different parts of the same line is easiest produced, and consequently by which the eye can make the best comparative measurements in its sweeps. All these merits single the normal position out to be chosen. No other point of view offers so many æsthetic and practical advantages. Here we believe we see the object as it _is_; elsewhere, only as it seems. Experience and custom soon teach us, however, that the seeming appearance passes into the real one by continuous gradations. They teach us, moreover, that seeming and being may be strangely interchanged. Now a real circle may slide into a seeming ellipse; now an ellipse may, by sliding in the same direction, become a seeming circle; now a rectangular cross grows slant-legged; now a slant-legged one grows rectangular.

Almost any form in oblique vision may be thus a derivative of almost any other in 'primary' vision; and we must learn, when we get one of the former appearances, to translate it into the appropriate one of the latter class; we must learn of what optical 'reality' it is one of the optical signs. Having learned this, we do but obey that law of economy or simplification which dominates our whole psychic life, when we attend exclusively to the 'reality' and ignore as much as our consciousness will let us the 'sign' by which we came to apprehend it. The signs of each probable real thing being multiple and the thing itself one and fixed, we gain the same mental relief by abandoning the former for the latter that we do when we abandon mental images, with all their fluctuating characters, for the definite and unchangeable _names_ which they suggest. The selection of the several 'normal' appearances from out of the jungle of our optical experiences, to serve as the real sights of which we shall think, is psychologically a parallel phenomenon to the habit of thinking in words, and has a like use. Both are substitutions of terms few and fixed for terms manifold and vague.


_Sensations which we Ignore._


This service of sensations as mere signs, to be ignored when they have evoked the other sensations which are their significates, was noticed first by Berkeley and remarked in many passages, as the following:

"Signs, being little considered in themselves, or for their own sake,
but only in their relative capacity and for the sake of those things
whereof they are signs, it comes to pass that the mind overlooks them,
so as to carry its attention immediately on to the things signified ...
which in truth and strictness are not _seen_, but only _suggested_ and
_apprehended_ by means of the proper objects of sight which alone are
seen." (Divine Visual Language, § 12.)

Berkeley of course erred in supposing that the thing suggested was not even _originally_ an object of sight, as the sign now is which calls it up. Reid expressed Berkeley's principle in yet clearer language:

"The visible appearances of objects are intended by nature only as
signs or indications, and the mind passes instantly to the things
signified, without making the least reflection upon the sign, or even
perceiving that there is any such thing.... The mind has acquired a
confirmed and inveterate habit of inattention to them (the signs). For
they no sooner appear than, quick as lightning, the thing signified
succeeds and engrosses all our regard. They have no name in language;
and although we are conscious of them when they pass through the mind,
yet their passage is so quick and so familiar that it is absolutely
unheeded; nor do they leave any footsteps of themselves, either in the
memory or imagination." (Inquiry, chap. v. §§ 2, 3.)

If we review the facts we shall find every grade of non-attention between the extreme form of overlooking mentioned by Reid (or forms even more extreme still) and complete conscious perception of the sensation present. Sometimes it is literally impossible to become aware of the latter. Sometimes a little artifice or effort easily leads us to discern it together, or in alternation, with the 'object' it reveals. Sometimes the present sensation is held to _be_ the object or to reproduce its features in undistorted shape, and _then_, of course, it receives the mind's full glare.

The deepest inattention is to subjective optical sensations, strictly so called, or those which are not signs of outer objects at all. Helmholtz's treatment of these phenomena, _muscæ volitantes_, negative after-images, double images, etc., is very satisfactory. He says:

"We only attend with any ease and exactness to our sensations in
so far forth as they can be utilized for the knowledge of outward
things; and we are accustomed to neglect all those portions of them
which have no significance as regards the external world. So much is
this the case that for the most part special artifices and practice
are required for the observation of these latter more subjective
feelings. Although it might seem that nothing should be easier than
to be conscious of one's own sensations, experience nevertheless
shows that often enough either a special talent like that showed in
eminent degree by Purkinje, or accident or theoretic speculation,
are necessary conditions for the discovery of subjective phenomena.
Thus, for example, the blind spot on the retina was discovered by
Mariotte by the theoretic way; similarly by me the existence of
'summation'-tones in acoustics. In the majority of cases accident is
what first led observers whose attention was especially exercised
on subjective phenomena to discover this one or that; only where
the subjective appearances are so intense that they interfere with
the perception of objects are they noticed by all men alike. But
if they have once been discovered it is for the most part easy for
subsequent observers who place themselves in proper conditions and
bend their attention in the right direction to perceive them. But
in many cases--for example, in the phenomena of the blind spot,
in the discrimination of over-tones and combination-tones from the
ground-tone of musical sounds, etc.--such a strain of the attention
is required, even with appropriate instrumental aids, that most
persons fail. The very after-images of bright objects are by most
men perceived only under exceptionally favorable conditions, and it
takes steady practice to see the fainter images of this kind. It
is a commonly recurring experience that persons smitten with some
eye-disease which impairs vision suddenly remark for the first time
the _muscæ volitantes_ which all through life their vitreous humor
has contained, but which they now firmly believe to have arisen since
their malady; the truth being that the latter has only made them
more observant of all their visual sensations. There are also cases
where one eye has gradually grown blind, and the patient lived for
an indefinite time without knowing it, until, through the accidental
closure of the healthy eye alone, the blindness of the other was
brought to attention.
"Most people, when first made aware of binocular double images, are
uncommonly astonished that they should never have noticed them before,
although all through their life they had been in the habit of seeing
singly only those few objects which were about equally distant with
the point of fixation, and the rest, those nearer and farther, which
constitute the great majority, had always been double.
"We must then _learn_ to turn our attention to our particular
sensations, and we learn this commonly only for such sensations
as are means of cognition of the outer world. Only so far as they
serve this end have our sensations any importance for us in ordinary
life. Subjective feelings are mostly interesting only to scientific
investigators; were they remarked in the ordinary use of the
senses, they could only cause disturbance. Whilst, therefore, we
reach an extraordinary degree of firmness and security in objective
observation, we not only do not reach this where subjective phenomena
are concerned, but we actually attain in a high degree the faculty
of overlooking these altogether, and keeping ourselves independent
of their influence in judging of objects, even in cases where their
strength might lead them easily to attract our attention." (Physiol.
Optik, pp. 431-2.)

Even where the sensation is not merely subjective, as in the cases of which Helmholtz speaks, but is a sign of something outward, we are also liable, as Reid says, to overlook its intrinsic quality and attend exclusively to the image of the 'thing' it suggests. But here everyone _can_ easily notice the sensation itself if he will. Usually we see a sheet of paper as uniformly white, although a part of it may be in shadow. But we can in an instant, if we please, notice the shadow as local color. A man walking towards us does not usually seem to alter his size; but we can, by setting our attention in a peculiar way make him appear to do so. The whole education of the artist consists in his learning to see the presented signs as well as the represented things. No matter what the field of view _means_, he sees it also as it _feels_--that is, as a collection of patches of color bounded by lines--the whole forming an optical diagram of whose intrinsic proportions one who is not an artist has hardly a conscious inkling. The ordinary man's attention passes _over_ them to their import; the artist's turns back and dwells _upon_ them for their own sake. 'Don't draw the thing as it _is_, but as it _looks_!' is the endless advice of every teacher to his pupil; forgetting that what it 'is' is what it would also 'look,' provided it were placed in what we have called the 'normal' situation for vision. In this situation the sensation as 'sign' and the sensation as 'object' coalesce into one, and there is no contrast between them.


_Sensations which seem Suppressed._


But a great difficulty has been made of certain peculiar cases which we must now turn to consider. They are _cases in which a present sensation, whose existence is supposed to be proved by its outward conditions being there, seems absolutely suppressed or changed by the image of the 'thing' it suggests._

This matter carries us back to what was said on p. 218. The passage there quoted from Helmholtz refers to these cases. He thinks they conclusively disprove the original and intrinsic spatiality of any of our retinal sensations; for if such a one, actually present, had an immanent and essential space-determination of its own, that might well be added to and overlaid or even momentarily eclipsed by suggestions of its signification, but how could it possibly be altered or completely _suppressed_ thereby? Of actually present sensations, he says, being _suppressed_ by suggestions of experience--

"We have not a single well-attested example. In all those illusions
which are provoked by _sensations_ in the absence of their usually
exciting objects, the mistake never vanishes by the better
understanding of the object really present, and by insight into the
cause of deception. Phosphenes provoked by pressure on the eyeball,
by traction on the entrance of the optic nerve, after-images, etc.,
remain projected into their apparent place in the field of vision,
just as the image projected from a mirror's surface continues to
be seen _behind_ the mirror, although we _know_ that to all these
appearances no outward reality corresponds. True enough, we can remove
our attention, and keep it removed, from sensations that have no
reference to the outer world, those, e.g., of the weaker after-images,
and of entoptic objects, etc.... But what would become of our
perceptions at all if we had the power not only of ignoring, but of
_transforming into their opposites_, any part of them that differed
from that outward experience, the image of which, as that of a present
reality, accompanies them in the mind?"[233]

And again:

"On the analogy of all other experience, we should expect that the
conquered feelings would persist to our perception, even if only in
the shape of recognized illusions. But this is not the case. One
does not see how the assumption of originally spatial sensations can
explain our optical cognitions, when in the last resort those who
believe in these very sensations find themselves obliged to assume
that they are _overcome_ by our better judgment, based on experience."

These words, coming from such a quarter, necessarily carry great weight. But the authority even of a Helmholtz ought not to shake one's critical composure. And the moment one abandons abstract generalities and comes to close quarters with the particulars, I think one easily sees that no such conclusions as those we have quoted follow from the latter. But profitably to conduct the discussion _we must divide the alleged instances into groups._

      *       *       *       *       *

(a) With Helmholtz, _color-perception_ is equally with space-perception an intellectual affair. The so-called simultaneous color-contrast, by which one color modifies another alongside of which it is said, is explained by him as an unconscious inference. In Chapter XVII we discussed the color-contrast problem; the principles which applied to its solution will prove also applicable to part of the present problem. In my opinion, Hering has definitively proved that, when one color is laid beside another, it modifies the sensation of the latter, not by virtue of any mere mental suggestion, as Helmholtz would have it, but by actually exciting a new nerve-process, to which the modified feeling of color immediately corresponds. The explanation is physiological, not psychological. The transformation of the original color by the inducing color is due to the disappearance of the physiological conditions under which the first color was produced, and to the induction, under the new conditions, of a genuine new sensation, with which the 'suggestions of experience' have naught to do.

[Illustration: FIG. 64.]

That processes in the visual apparatus propagate themselves laterally, if one may so express it, is also shown by the _phenomena of contrast which occur after looking upon motions_ of various kinds. Here are a few examples. If, over the rail of a moving vessel, we look at the water rushing along the side, and then transfer our gaze to the deck, a band of planks will appear to us, moving in the opposite direction to that in which, a moment previously, we had been seeing the water move, whilst on either side of this band another band of planks will move as the water did. Looking at a waterfall, or at the road from out of a car-window in a moving tram, produces the same illusion, which may be easily verified in the laboratory by a simple piece of apparatus. A board with a window five or six inches wide and of any convenient length is supported upright on two feet. On the back side of the board, above and below the window, are two rollers, one of which is provided with a crank. An endless band of any figured stuff is passed over these rollers (one of which can be so adjusted on its bearings as to keep the stuff always taut and not liable to slip), and the surface of the front board is also covered with stuff or paper of a nature to catch the eye. Turning the crank now sets the central band in continuous motion, whilst the margins of the field remain really at rest, but after a while appear moving in the contrary way. Stopping the crank results in an illusory appearance of motion in reverse directions all over the field.

A disk with an Archimedean spiral drawn upon it, whirled round on an ordinary rotating machine, produces still more startling effects.

[Illustration: FIG. 65.]

"If the revolution is in the direction in which the spiral line
approaches the centre of the disk the entire surface of the latter
seems to expand during revolution and to contract after it has ceased;
and _vice versâ_ if the movement of revolution is in the opposite
direction. If in the former case the eyes of the observers are turned
from the rotating disk towards any familiar object--e.g. the face of a
friend--the latter seems to contract or recede in a somewhat striking
manner, and to expand or approach after the opposite motion of the
spiral."[234]

[Illustration: FIG. 66.]

An elementary form of these motor illusions seems to be the one described by Helmholtz on pp. 568-571 of his Optik. The motion of anything in the field of vision along an acute angle towards a straight line sensibly distorts that line. Thus in Fig. 66: Let AB be a line drawn on paper, CDE the tracing made over this line by the point of a compass steadily followed by the eye, as it moves. As the compass-point passes from C to D, the line appears to move downwards; as it passes from D to E, the line appears to move upwards; at the same time the whole line seems to incline itself in the direction FG during the first half of the compass's movement; and in the direction HI during its last half; the change from one inclination to another being quite distinct as the compass-point passes over D.

Any line across which we draw a pencil-point appears to be animated by a rapid movement of its own towards the pencil-point. This apparent movement of both of two things in relative motion to each other, even when one of them is absolutely still, reminds us of the instances quoted from Vierordt on page 188, and seems to take us back to a primitive stage of perception, in which the discriminations we now make when we feel a movement have not yet been made. If we draw the point of a pencil through 'Zöllner's pattern' (Fig. 60, p. 232), and follow it with the eye, the whole figure becomes the scene of the most singular apparent unrest, of which Helmholtz has very carefully noted the conditions. The illusion of Zöllner's figure vanishes entirely, or almost so, with most people, if they steadily look at one point of it with an unmoving eye; and the same is the case with many other illusions.

_Now all these facts taken together seem to show_--vaguely it is true, but certainly--_that present excitements and after-effects of former excitements may alter the result of processes occurring simultaneously at a distance from them in the retina_ or other portions of the apparatus for optical sensation. In the cases last considered, the moving eye, as it sweeps the fovea over certain parts of the figure, seems thereby to determine a modification in the feeling which the _other_ parts confer, which modification is the figure's 'distortion.' It is true that this statement explains nothing. It only keeps the cases to which it applies from being explained spuriously. _The spurious account of these illusions is that they are intellectual, not sensational, that they are secondary, not primary, mental facts._ The distorted figure is said to be one which the mind is led to _imagine_, by falsely drawing an unconscious inference from certain premises of which it is not distinctly aware. And the imagined figure is supposed to be strong enough to suppress the perception of whatever real sensations there may be. But Helmholtz, Wundt, Delbœuf, Zöllner, and all the advocates of unconscious inference are at variance with each other when it comes to the question what these unconscious premises and inferences may be.

[Illustration: FIG. 67.]

[Illustration: FIG. 68.]

That small angles look proportionally larger than larger ones is, in brief, the fundamental illusion to which almost all authors would reduce the peculiarity of Fig. 67, as of Figs. 60, 61, 62 (p. 232). This peculiarity of small angles is by Wundt treated as the case of a filled space seeming larger than an empty one, as in Fig. 68; and this, according to both Delbœuf and Wundt, is owing to the fact that more muscular innervation is needed for the eye to traverse a filled space than an empty one, because the points and lines in the filled space inevitably arrest and constrain the eye, and this makes us feel as if it were doing more work, i.e. traversing a longer distance.[235] When, however, we recollect that muscular movements are positively proved to have _no_ share in the waterfall and revolving-spiral illusions, and that it is hard to see how Wundt's and Delbœuf's particular form of muscle-explanation can possibly apply to the compass-point illusion considered a moment ago, we must conclude that these writers have probably exaggerated, to say the least, the reach of their muscle-explanation in the case of the subdivided angles and lines. Never do we get such strong muscular feelings as when, against the course of nature, we oblige our eyes to be still; but fixing the eyes on one point of the figure, so far from making that part of the latter seem larger, dispels, in most persons, the illusion of these diagrams altogether.

As for Helmholtz, he invokes, to explain the enlargement of small angles,[236] what he calls a '_law of contrast_' between directions and distances of lines, analogous to that between colors and intensities of light. Lines cutting another line make the latter seem more inclined away from them than it really is. Moreover, clearly recognizable magnitudes appear greater than equal magnitudes which we but vaguely apprehend. But this is surely a sensationalistic law, a native function of our seeing-apparatus. Quite as little as the negative after-image of the revolving spiral could such contrast be deduced from any association of ideas or recall of past objects. The principle of contrast is criticised by Wundt,[237] who says that by it small spaces ought to appear to us smaller, and not larger, than they really are. Helmholtz might have retorted (had not the retort been as fatal to the uniformity of his own principle as to Wundt's) that if the muscle-explanation were true, it ought not to give rise to just the opposite illusions in the skin. We saw on p. 141 that subdivided spaces appear shorter than empty ones upon the skin. To the instances there given add this: Divide a line on paper into equal halves, puncture the extremities, and make punctures all along one of the halves; then, with the finger-tip on the opposite side of the paper, follow the line of punctures; the empty half will seem much longer than the punctured half. This seems to bring things back to unanalyzable laws, by reason of which our feeling of size is determined differently in the skin and in the retina, even when the objective conditions are the same. Hering's explanation of Zöllner's figure is to be found in Hermann's Handb. d. Physiologie, iii. 1. p. 579. Lipps[238] gives another reason why lines cutting another line make the latter seem to bend away from them more than is really the case. If, he says, we draw (Fig. 69) the line _pm_ upon the line _ab_, and follow the latter with our eye, we shall, on reaching the point _m_, tend for a moment to slip off _ab_ and to follow _mp_, without distinctly realizing that we are not still on the main line. This makes us feel as if the remainder _mb_ of the main line were bent a little away from its original direction. The illusion is apparent in the shape of a seeming approach of the ends _b, b,_ of the two main lines. This to my mind would be a more satisfactory explanation of this class of illusions than any of those given by previous authors, were it not again for what happens in the skin.

[Illustration: FIG. 69.]

_Considering all the circumstances, I feel justified in discarding his entire batch of illusions as irrelevant to our present inquiry._ Whatever they may prove, they do not prove that our visual percepts of form and movement may not be sensations strictly so called. They much more probably fall into line with the phenomena of irradiation and of color-contrast, and with Vierordt's primitive illusions of movement. They show us, if anything, a realm of sensations in which our habitual experience has not yet made traces, and which persist in spite of our better knowledge, _un_suggestive of those other space-sensations which we all the time know from extrinsic evidence to constitute the real space-determinations of the diagram. Very likely, if these sensations were as frequent and as practically important as they now are insignificant and rare, we should end by substituting their significates--the real space-values of the diagrams--for them. These latter we should then seem to see directly, and the illusions would disappear like that of the size of a tooth-socket when the tooth has been out a week.

      *       *       *       *       *

_(b) Another batch of cases which we may discard is that of double images_. A thoroughgoing anti-sensationalist ought to deny all native tendency to see double images when disparate retinal points are stimulated, because, he should say, most people never get them, but _see_ all things single which experience has led them to believe to _be_ single. "Can a doubleness, so easily neutralized by our knowledge, ever be a datum of sensation at all?" such an anti-sensationalist might ask.

[Illustration: FIG. 70.]

To which the answer is that it _is_ a datum of sensation, but a datum which, like many other data, must first be _discriminated_. As a rule, no sensible qualities are discriminated without a motive.[239] And those that later we learn to discriminate were originally felt confused. As well pretend that a voice, or an odor, which we have learned to pick out, is no sensation now. One may easily acquire skill in discriminating double images, though, as Hering somewhere says, it is an art of which one cannot become master in one year or in two. For masters like Hering himself, or Le Conte, the ordinary stereoscopic diagrams are of little use. Instead of combining into one solid appearance, they simply cross each other with their doubled lines. Volkmann has shown a great variety of ways in which the addition of secondary lines, differing in the two fields, helps us to see the primary lines double. The effect is analogous to that shown in the cases which we despatched a moment ago, where given lines have their space-value changed by the addition of new lines, without our being able to say why, except that a certain mutual adhesion of the lines and modification of the resultant feeling takes place by psychophysiological laws. Thus, if in Fig. 70, _l_ and _r_ be crossed by an horizontal line at the same level, and viewed stereoscopically, they appear as a single pair of lines, _s_, in space. But if the horizontal be at different levels, as in _l', r',_ three lines appear, as in _s'_'.[240]

Let us then say no more about double images. All that the facts prove is what Volkmann says,[241] that, although there may be sets of retinal fibres so organized as to give an impression of two separate spots, yet the excitement of other retinal fibres may inhibit the effect of the first excitement, and prevent us from actually making the discrimination. Still farther retinal processes may, however, bring the doubleness to the eye of attention; and, once there, it is as genuine a sensation as any that our life affords.[242]

      *       *       *       *       *

_(c) These groups of illusions being eliminated,_ either as cases of defective discrimination, or as changes of one space-sensation into another when the total retinal process changes, _there remain but two other groups to puzzle us._ The first is that of the after-images distorted by projection on to oblique planes; the second relates to the instability of our judgments of relative distance and size by the eye, and includes especially what are known as pseudoscopic illusions.

The phenomena of the first group were described on page 232. A. W. Volkmann has studied them with his accustomed clearness and care.[243] Even an imaginarily inclined wall, in a picture, will, if an after-image be thrown upon it, distort the shape thereof, and make us _see_ a form of which our after-image would be the natural projection on the retina, were that form laid upon the wall. Thus a signboard is painted in perspective on a screen, and the eye, after steadily looking at a rectangular cross, is turned to the painted signboard. The after-image appears as an oblique-legged cross upon the signboard. It is the converse phenomenon of a perspective drawing like Fig. 71, in which really oblique-legged figures are seen as rectangular crosses.

[Illustration: FIG. 71.]

[Illustration: FIG. 72.]

[Illustration: FIG. 73.]

The unstable judgments of relative distance and size were also mentioned on pp. 231-2. Whatever the size may be of the retinal image which an object makes, the object is seen as of its own normal size. A man moving towards us is not sensibly perceived to _grow_, for example; and my finger, of which a single joint may more than conceal him from my view, is nevertheless seen as a much smaller object than the man. As for distances, it is often possible to make the farther part of an object seem near and the nearer part far. A human profile in intaglio, looked at steadily with one eye, or even both, soon appears irresistibly as a bas-relief. The inside of a common pasteboard mask, painted like the outside, and viewed with one eye in a direct light, also looks convex instead of hollow. So strong is the illusion, after long fixation, that a friend who painted such a mask for me told me it soon became difficult to see how to apply the brush. Bend a visiting-card across the middle, so that its halves form an angle of 90º more or less; set it upright on the table, as in Fig. 72, and view it with one eye. You can make it appear either as if it opened towards you or away from you. In the former case, the angle _ab_ lies upon the table, _b_ being nearer to you than _a_; in the latter case _ab_ seems vertical to the table--as indeed it really is--with _a_ nearer to you than _b_.[244] Again, look, with either one or two eyes, at the opening of a wine-glass or tumbler (Fig. 73), held either above or below the eye's level. The retinal image of the opening is an oval, but we can see the oval in either of two ways,--as if it were the perspective view of a circle whose edge _b_ were farther from us than its edge _a_ (in which case we should seem to be looking down on the circle), or as if its edge _a_ were the more distant edge (in which case we should be looking up at it through the _b_ side of the glass). As the manner of seeing the edge changes, the glass itself alters its form in space and looks straight or seems bent towards or from the eye,[245] according as the latter is placed beneath or above it.

[Illustration: FIG. 74.]

[Illustration: FIG. 75.]

[Illustration: FIG. 76.]

Plane diagrams also can be conceived as solids, and that in more than one way. Figs. 74, 75, 76, for example, are ambiguous perspective projections, and may each of them remind us of two different natural objects. Whichever of these objects we conceive clearly at the moment of looking at the figure, we seem to _see_ in all its solidity before us. A little practice will enable us to flap the figures, so to speak, backwards and forwards from one object to the other at will. We need only attend to one of the angles represented, and imagine it either solid or hollow--pulled towards us out of the plane of the paper, or pushed back behind the same--and the whole figure obeys the cue and is instantaneously transformed beneath our gaze.[246]

The peculiarity of all these cases is the ambiguity of the perception to which the fixed retinal impression gives rise. With our retina excited in exactly the same way, whether by after-image, mask or diagram, we _see_ now this object and now that, as if the retinal image _per se_ had no essential space-import. Surely if form and length were originally retinal sensations, retinal rectangles ought not to become acute or obtuse, and lines ought not to alter their relative lengths as they do. If _relief_ were an optical feeling, it ought not to flap to and fro, with every optical condition unchanged. Here, if anywhere, the deniers of space-sensation ought to be able to make their final stand.[247]

It must be confessed that their plea is plausible at first sight. But it is one thing to throw out retinal sensibility altogether as a space-yielding function the moment we find an ambiguity in its deliverances, and another thing to examine candidly the conditions which may have brought the ambiguity about. The former way is cheap, wholesale, shallow; the latter difficult and complicated, but full of instruction in the end. Let us try it for ourselves.

      *       *       *       *       *

In the case of the diagrams 72, 73, 74, 75, 76, the real object, lines meeting or crossing each other on a plane, is replaced by an _imagined solid which we describe as seen. Really it is not seen but only so vividly conceived as to approach a vision of reality._ We feel all the while, however, that the solid suggested is not solidly there. _The reason_ why one solid may seem more easily suggested than another, and _why it is easier in general to perceive the diagram solid than flat, seems due to probability._[248] Those lines have countless times in our past experience been drawn on our retina by solids for once that we have seen them flat on paper. And hundreds of times we have looked down upon the upper surface of parallelopipeds, stairs and glasses, for once that we have looked upwards at their bottom--hence we see the solids easiest as if from above.

Habit or probability seems also to govern the illusion of the intaglio profile, and of the hollow mask. We have _never_ seen a human face except in relief--hence the case with which the present sensation is overpowered. Hence, too, the obstinacy with which human faces and forms, and other extremely familiar convex objects, refuse to appear hollow when viewed through Wheatstone's pseudoscope. Our perception seems wedded to certain total ways of seeing certain objects. The moment the object is suggested at all, it takes possession of the mind in the fulness of its stereotyped habitual form. This explains the suddenness of the transformations when the perceptions change. The object shoots back and forth completely from this to that familiar thing, and doubtful, indeterminate, and composite things are excluded, apparently because we are _unused_ to their existence.

When we turn from the diagrams to the actual folded visiting-card and to the real glass, the imagined form seems fully as real as the correct one. The card flaps over; the glass rim tilts this way or that, as if some inward spring suddenly became released in our eye. In these changes the actual retinal image receives different _complements from the mind_. But the remarkable thing is that the complement and the image combine so completely that the twain are one flesh, as it were, and cannot be discriminated in the result. If the complement be, as we have called it (on pp. 237-8), a set of imaginary absent eye-sensations, they seem no whit less vividly there than the sensation which the eye now receives from without.

The case of the after-images distorted by projection upon an oblique plane is even more strange, for the imagined perspective figure, lying in the plane, seems less to combine with the one a moment previously seen by the eye than to suppress it and take its place.[249] The point needing explanation, then, in all this, is how it comes to pass that, when imagined sensations are usually so inferior in vivacity to real ones, they should in these few experiences prove to be almost or quite their match.

The mystery is solved when we note the class to which all these experiences belong. They are 'perceptions' of definite 'things,' definitely situated in tridimensional space. The mind uniformly uses its sensations to _identify things by_. The sensation is invariably apperceived by the idea, name, or 'normal' aspect (p. 238) of the _thing_. The peculiarity of the _optical_ signs of things is their extraordinary mutability. A 'thing' which we follow with the eye, never doubting of its physical identity, will change its retinal image incessantly. A cross, a ring, waved about in the air, will pass through every conceivable angular and elliptical form. All the while, however, as we look at them, we hold fast to the perception of their 'real' shape, by mentally combining the pictures momentarily received with the notion of peculiar positions in space. It is not the cross and ring pure and simple which we perceive, but the cross _so held_, the ring _so held_. From the day of our birth we have sought every hour of our lives to _correct_ the apparent form of things, and translate it into the real form by keeping note of the way they are placed or held. In no other class of sensations does this incessant correction occur. What wonder, then, that the notion 'so placed' should invincibly exert its habitual corrective effect, even when the object with which it combines is only an after-image, and make us perceive the latter under a changed but more 'real' form? The 'real' form is also a sensation conjured up by memory; but it is one so _probable_, so _habitually_ conjured up when we have just this combination of optical experiences, that it partakes of the invincible freshness of reality, and seems to break through that law which elsewhere condemns reproductive processes to being so much fainter than sensations.

Once more, _these cases form an extreme. Somewhere, in the list of our imaginations of absent feelings, there must be found the vividest of all. These optical reproductions of real form are the vividest of all._ It is foolish to reason from cases lower in the scale, to prove that the scale can contain no such extreme cases as these; and particularly foolish since we can definitely see why these imaginations ought to be more vivid than any others, whenever they recall the forms of habitual and probable things. These latter, by incessantly repeated presence and reproduction, will plough deep grooves in the nervous system. There will be developed, to correspond to them, paths of least resistance, of unstable equilibrium, liable to become active in their totality when any point is touched off. Even when the objective stimulus is imperfect, we shall still _see_ the full convexity of a human face, the correct inclination of an angle or sweep of a curve, or the distance of two lines. Our mind will be like a polyhedron, whose facets are the attitudes of perception in which it can most easily rest. These are worn upon it by _habitual_ objects, and from one of these it can pass only by tumbling over into another.[250]

Hering has well accounted for the sensationally vivid character of these habitually reproduced forms. He says, after reminding us that every visual sensation is correlated to a physical process in the nervous apparatus:

"If this psycho-physical process is aroused, as usually happens, by
light-rays impinging on the retina, its form depends not only on the
nature of these rays, but on the constitution of the entire nervous
apparatus which is connected with the organ of vision, and on the
_state_ in which it finds itself. The same stimulus may excite widely
different sensations according to this state.
"The constitution of the nervous apparatus depends naturally in part
upon innate predisposition; but the _ensemble_ of effects wrought by
stimuli upon it in the course of life, whether these come through the
eyes or from elsewhere, is a co-factor of its development. To express
it otherwise, involuntary and voluntary experience and exercise assist
in determining the material structure of the nervous organ of vision,
and hence the ways in which it may react on a retinal image as an
outward stimulus. That experience and exercise should be possible at
all in vision is a consequence of the reproductive power, or memory,
of its nerve-substance. Every particular activity of the organ makes
it more suited to a repetition of the _same_; ever slighter touches
are required to make the repetition occur. The organ habituates itself
to the repeated activity....
"Suppose now that, in the first experience of a complex sensation
produced by a particular retinal image, certain portions were made
the special objects of attention. In a repetition of the sensible
experience it will happen that notwithstanding the identity of the
outward stimulus these portions will be more easily and strongly
reproduced; and when this happens a hundred times the inequality with
which the various constituents of the complex sensation appeal to
consciousness grows ever greater.
"Now in the present state of our knowledge we cannot assert that
in both the first and the last occurrence of the retinal image
in question the same _pure sensation_ is provoked, but that the
mind _interprets_ it differently the last time in consequence of
experience; for the only _given_ things we know are on the one hand
the retinal image which is both times the same, and on the other the
mental percept which is both times different; of a third thing, such
as a pure sensation, interpolated between image and percept, we know
nothing. We ought, therefore, if we wish to avoid hypotheses, simply
to say that the nervous apparatus reacts the last time differently
from the first, and gives us in consequence a different group of
sensations.
"But not only by repetition of the same retinal image, but by that of
similar ones, will the law obtain. Portions of the image common to
the successive experiences will awaken, as it were, a stronger echo
in the nervous apparatus than other portions. Hence it results that
_reproduction is usually elective_: the more strongly reverberating
parts of the picture yield stronger feelings than the rest. This
may result in the latter being quite overlooked and, as it were,
eliminated from perception. It may even come to pass that instead of
these parts eliminated by election a feeling of entirely different
elements comes to consciousness-elements not objectively contained
in the stimulus. A group of sensations, namely, for which a strong
tendency to reproduction has become, by frequent repetition, ingrained
in the nervous system will easily revive as a _whole_ when, not its
whole retinal image, but only an essential part thereof, returns.
In this case we get some sensations to which no adequate stimulus
exists in the retinal image, and which owe their being solely to the
reproductive power of the nervous apparatus. This is _complementary
(ergänzende) reproduction_.
"Thus a few points and disconnected strokes are sufficient to make
us see a human face, and without specially directed attention we
fail to note that we see much that really is not drawn on the paper.
Attention will show that the outlines were deficient in spots where
we thought them complete.... The portions of the percept supplied by
complementary reproduction depend, however, just as much as its other
portions, on the reaction of the nervous apparatus upon the retinal
image, indirect though this reaction may, in the case of the supplied
portions, be. And so long as they are present, we have a perfect
right to call them sensations, for they differ in no wise from such
sensations as correspond to an actual stimulus in the retina. Often,
however, they are not persistent; many of them may be expelled by more
close observation, but this is not proved to be the case with all....
In vision with one eye ... the distribution of parts within the third
dimension is essentially the work of this complementary reproduction,
i.e. of former experience.... When a certain way of localizing a
particular group of sensations has become with us a second nature,
our better knowledge, our judgment, our logic, are of no avail....
Things actually diverse may give similar or almost identical retinal
images; e.g., an object extended in three dimensions, and its
flat perspective picture. In such cases it often depends on small
accidents, and especially on our will, whether the one or the other
group of sensations shall be excited.... We can see a relief hollow,
as a mould, or _vice versâ_; for a relief illuminated from the left
can look just like its mould illuminated from the right. Reflecting
upon this, one may infer from the direction of the shadows that one
has a relief before one, and the idea of the relief will guide the
nerve-processes into the right path, so that _the feeling_ of the
relief is suddenly aroused.... Whenever the retinal image is of such a
nature that two diverse modes of reaction on the part of the nervous
apparatus are, so to speak, equally, or nearly equally, imminent, it
must depend on small accidents whether the one or the other reaction
is realized. In these cases our previous knowledge often has a
decisive effect, and helps the correct perception to victory. The
bare idea of the right object is itself a feeble reproduction which
with the help of the proper retinal picture develops into clear and
lively sensation. But if there be not already in the nervous apparatus
a disposition to the production of that percept which our judgment
tells us is right, our knowledge strives in vain to conjure up the
feeling of it; we then know that we see something to which no reality
corresponds, but we see it all the same."[251]

[Illustration: FIG. 77.]

_Note that no object not probable, no object which we are not incessantly practised in reproducing, can acquire this vividness in imagination._ Objective corners are ever changing their angles to the eyes, spaces their apparent size, lines their distance. But by no transmutation of position in space does an objective straight line appear bent, and only in one position out of an infinity does a broken line look straight. Accordingly, it is impossible by projecting the after-image of a straight line upon two surfaces which make a solid angle with each other to give the line itself a sensible 'kink.' Look with it at the corner of your room: the after-image, which may overlap all three surfaces of the corner, still continues straight. Volkmann constructed a complicated surface of projection like that drawn in Fig. 77, but he found it impossible so to throw a straight after-image upon it as to alter its visible form.

One of the situations in which we oftenest see things is spread out on the ground before us. We are incessantly drilled in making allowance for _this_ perspective, and reducing things to their real form in spite of optical foreshortening. Hence if the preceding explanations are true, we ought to find this habit inveterate. The _lower_ half of the retina, which habitually sees the _farther_ half of things spread out on the ground, ought to have acquired a habit of enlarging its pictures by imagination, so as to make them more than equal to those which fall on the upper retinal surface; and this habit ought to be hard to escape from, even when both halves of the object are equidistant from the eye, as in a vertical line on paper. Delbœuf has found, accordingly, that if we try to bisect such a line we place the point of division about of its length too high.[252]

[Illustration: FIG. 78.]

Similarly, a square cross, or a square, drawn on paper, should look higher than it is broad. And that this is actually the case, the reader may verify by a glance at Fig. 78. For analogous reasons the upper and lower halves of the letter S, or of the figure 8, hardly seem to differ. But when turned upside down, the upper half looks much the larger.[253]

[Illustration: FIG. 79.]

Hering has tried to explain our exaggeration of small angles in the same way. We have more to do with right angles than with any others: right angles, in fact, have an altogether unique sort of interest for the human mind. Nature almost never begets them, but we think space by means of them and put them everywhere. Consequently obtuse and acute ones, liable always to be the images of right ones foreshortened, particularly easily revive right ones in memory. It is hard to look at such figures as _a, b, c,_ in Fig. 79, without seeing them in perspective, as approximations, at least, to foreshortened rectangular forms.[254]

At the same time the genuine sensational form of the lines before us can, in all the cases of distortion by suggested perspective, be felt correctly by a mind able to abstract from the notion of perspective altogether. Individuals differ in this abstracting power. Artistic training improves it, so that after a little while errors in vertical bisection, in estimating height relatively to breadth, etc., become impossible. In other words, we learn to take the optical sensation before us _pure_.[255]

_We may then sum up our study of illusions by saying that they in no wise undermine our view that every spatial determination of things is originally given in the shape of a sensation of the eyes._ They only show how very potent certain _imagined_ sensations of the eyes may become.

These sensations, so far as they bring definite forms to the mind, appear to be retinal exclusively. The movements of the eyeballs play a great part in educating our perception, it is true; but they have nothing to do with _constituting_ any one feeling of form. Their function is limited to _exciting_ the various feelings of form, by tracing retinal streaks; and to _comparing_ them, and _measuring_ them off against each other, by applying different parts of the retinal surface to the same objective thing. Helmholtz's analysis of the facts of our '_measurement of the field of view_' is, bating a lapse or two, masterly, and seems to prove that the movements of the eye have had some part in bringing our sense of retinal equivalencies about--_equivalencies_, mind, of different retinal forms and sizes, not forms and sizes themselves. _Superposition_ is the way in which the eye-movements accomplish this result. An object traces the line AB on a peripheral tract of the retina. Quickly we move the eye so that the same object traces the line _ab_ on a central tract. Forthwith, to our mind, AB and _ab_ are judged equivalent. But, as Helmholtz admits, the equivalence-judgment is independent of the way in which we may feel the form and length of the several retinal pictures themselves:

"The retina is like a pair of compasses, whose points we apply in
succession to the ends of several lines to see whether they agree
or not in length. All we need know meanwhile about the compasses
is that the distance of their points remains unchanged. What that
distance is, and what is the shape of the compasses, is a matter of no
account."[256]

_Measurement implies a stuff to measure. Retinal sensations give the stuff; objective things form the yardstick; motion does the measuring operation;_ which can, of course, be well performed only where it is possible to make the same object fall on many retinal tracts. This is practically impossible where the tracts make a wide angle with each other. But there are certain directions in the field of view, certain retinal lines, along which it is particularly easy to make the image of an object slide. The object then becomes a 'ruler' for these lines, as Helmholtz puts it,[257] making them seem straight throughout if the object looked straight to us in that part of them at which it was most distinctly seen.

But all this need of superposition shows how devoid of exact space-import the feelings of movement are _per se_. As we compare the space-value of two retinal tracts by superposing them successively upon the same objective line, so we also have to compare the space-value of objective angles and lines by superposing them on the same retinal tract. Neither procedure would be required if our eye-movements were apprehended immediately, by pure muscular feeling or innervation, for example, as distinct lengths and directions in space. To compare retinal tracts, it would then suffice simply to notice how it feels to move _any_ image over them. And two objective lines could be compared as well by moving different retinal tracts along them as by laying them along the same. It would be as easy to compare non-parallel figures as it now is to judge of those which are parallel.[258] Those which it took the same amount of movement to traverse would be equal, in whatever direction the movement occurred.


GENERAL SUMMARY.


With this we may end our long and, I fear to many readers, tediously minute survey. The facts of vision form a jungle of intricacy; and those who penetrate deeply into physiological optics will be more struck by our omissions than by our abundance of detail. But for students who may have lost sight of the forest for the trees, I will recapitulate briefly the points of our whole argument from the beginning, and then proceed to a short historical survey, which will set them in relief.

All our sensations are positively and inexplicably extensive wholes.

The sensations contributing to space-_perception_ seem exclusively to be the surface of skin, retina, and joints. 'Muscular' feelings play no appreciable part in the generation of our feelings of form, direction, etc.

The total bigness of a cutaneous or retinal feeling soon becomes subdivided by discriminative attention.

_Movements_ assist this discrimination by reason of the peculiarly exciting quality of the sensations which stimuli moving over surfaces arouse.

Subdivisions, once discriminated, acquire definite relations of position towards each other within the total space. These 'relations' are themselves feelings of the subdivisions that intervene. When these subdivisions are not the seat of stimuli, the relations are only reproduced in imaginary form.

The various sense-spaces are, in the first instance, incoherent with each other; and primitively both they and their subdivisions are but vaguely comparable in point of bulk and form.

The _education_ of our space-perception consists largely of two processes--reducing the various sense-feelings to a common _measure_, and _adding them together_ into the single all-including space of the real world.

Both the measuring and the adding are performed by the aid of _things_.

The imagined aggregate of positions occupied by all the actual or possible, moving or stationary, things which we know, is our notion of 'real' space--a very incomplete and vague conception in all minds.

The _measuring_ of our space-feelings against each other mainly comes about through the successive arousal of different ones by the same _thing_, by our selection of certain ones as feelings of its _real_ size and shape, and by the degradation of others to the status of being merely _signs_ of these.

For the successive application of the same thing to different space-giving surfaces motion is indispensable, and hence plays a great part in our space-education, especially in that of the eye. Abstractly considered, the motion of the object over the sensitive surface would educate us quite as well as that of the surface over the object. But the self-mobility of the organ carrying the surface _accelerates_ immensely the result.

In completely educated space-perception, the present sensation is usually just what Helmholtz (Physiol. Optik, p. 797) calls it, 'a sign, the interpretation of whose meaning is left to the understanding.' But the understanding is exclusively reproductive and never productive in the process; and its function is limited to the recall of previous space-sensations with which the present one has been associated and which may be judged more real than it.

Finally, this reproduction may in the case of certain visual forms be as vivid, or almost so, as actual sensation is.

The third dimension forms an original element of all our space-sensations. In the eye it is subdivided by various discriminations. The more distant subdivisions are often shut out altogether, and, in being suppressed, have the effect of diminishing the absolute space-value of the total field of view.[259]


HISTORICAL.


Let us now close with a brief historical survey. The first achievement of note in the study of space-perception was Berkeley's theory of vision. This undertook to establish two points, first that _distance_ was not a visual but a tactile form of consciousness, suggested by visual signs; secondly, that there is no one quality or 'idea' common to the sensations of touch and sight, such that prior to experience one might possibly anticipate from the look of an object anything about its felt size, shape, or position, or from the touch of it anything about its look.

In other words, that primitively chaotic or semi-chaotic condition of our various sense-spaces which we have demonstrated, was established for good by Berkeley; and he bequeathed to psychology the problem of describing the manner in which the deliverances are harmonized so as all to refer to one and the same extended world.

His disciples in Great Britain have solved this problem after Berkeley's own fashion, and to a great extent as we have done ourselves, by the ideas of the various senses suggesting each other in consequence of Association. But, either because they were intoxicated with the principle of association, or because in the number of details they lost their general bearings, they have forgotten, as a rule, to state _under what sensible form the primitive spatial experiences are found_ which later became associated with so many other sensible signs. Heedless of their master Locke's precept, that the mind can frame unto itself no one new simple idea, they seem for the most part to be trying to _explain the extensive quality itself_, account for it, and evolve it, by the mere association together of feelings which originally possessed it not. They first evaporate the nature of extension by making it tantamount to mere 'coexistence,' and then they explain coexistence as being the same thing as _succession_, provided it be an extremely rapid or a reversible succession. Space-perception thus emerges without being anywhere postulated. The only things postulated are unextended feelings and time. Says Thomas Brown (lecture xxiii.): "I am inclined to reverse exactly the process commonly supposed; and instead of deriving the measure of time from extension, to derive the knowledge and original measure of extension from time." Brown and both the Mills think that retinal sensations, colors, in their primitive condition, are felt with no extension and that the latter merely becomes inseparably associated with them. John Mill says: "Whatever may be the retinal impression conveyed by a line which bounds two colors, I see no ground for thinking that by the eye alone we could acquire the conception of what we now mean when we say that one of the colors is outside [beside] the other."[260]

Whence does the extension come which gets so inseparably associated with these non-extended colored sensations? From the 'sweep and movements' of the _eye_--from muscular feelings. But, as Prof. Bain says, if movement-feelings give us any property of things, "it would seem to be not space, but time."[261] And John Mill says that "the idea of space is, at bottom, one of time."[262] Space, then, is not to be found in any elementary sensation, but, in Bain's words, "as a quality, it has no other origin and no other meaning than the _association_ of these different [non-spatial] motor and sensitive effects."[263]

This phrase is mystical-sounding enough to one who understands association as _producing_ nothing, but only as knitting together things already produced in separate ways. The truth is that the English Associationist school, in trying to show how much their principle can accomplish, have altogether overshot the mark and espoused a kind of theory in respect to space-perception which the general tenor of their philosophy should lead them to abhor. Really there are but three possible kinds of theory concerning space. Either (1) there is no spatial _quality_ of sensation at all, and space is a mere symbol of succession; or (2) there is an _extensive quality given_ immediately in certain particular sensations; or, finally, (3) there is a _quality produced_ out of the inward resources of the mind, to envelop sensations which, as given originally, are not spatial, but which, on being cast into the spatial form, become united and orderly. This last is the Kantian view. Stumpf admirably designates it as the 'psychic stimulus' theory, the crude sensations being considered as goads to the mind to put forth its slumbering power.

Brown, the Mills, and Bain, amid these possibilities, seem to have gone astray like lost sheep. With the 'mental chemistry' of which the Mills speak--precisely the same thing as the 'psychical synthesis' of Wundt, which, as we shall soon see, is a principle expressly intended to do what Association can never perform--they hold the third view, but again in other places imply the first. And, between the impossibility of getting from mere association anything not contained in the sensations associated and the dislike to allow spontaneous mental productivity, they flounder in a dismal dilemma. Mr. Sully joins them there in what I must call a vague and vacillating way. Mr. Spencer of course is bound to pretend to 'evolve' all mental qualities out of antecedents different from themselves, so that we need perhaps not wonder at his refusal to accord the spatial quality to any of the several elementary sensations out of which our space-perception grows. Thus (Psychology, ii. 168, 172, 218):

"No idea of extension can arise from a _simultaneous_ excitation" of a
multitude of nerve-terminations like those of the skin or the retina,
since this would imply a "knowledge of their relative positions"--that
is, "a pre-existent idea of a special extension, which is absurd." "No
relation between _successive_ states of consciousness gives in itself
any idea of extension." "The muscular sensations accompanying motion
are quite distinct from the notions of space and time associated with
them."

Mr. Spencer none the less inveighs vociferously against the Kantian position that space is produced by the mind's own resources. And yet he nowhere denies space to be a specific affection of consciousness different from time!

Such incoherency is pitiful. The fact is that, at bottom, all these authors are really 'psychical stimulists,' or Kantists. The space they speak of is a super-sensational mental product. This position appears to me thoroughly mythological. But let us see how it is held by those who know more definitely what they mean. Schopenhauer expresses the Kantian view with more vigor and clearness than anyone else. He says:

"A man must be forsaken by all the gods to dream that the world we
see outside of us, filling space in its three dimensions, moving down
the inexorable stream of time, governed at each step by Causality's
invariable law,--but in all this only following rules which we may
prescribe for it in advance of all experience,--to dream, I say, that
such a world should stand there outside of us, quite objectively real
with no complicity of ours, and thereupon by a subsequent _act_,
through the instrumentality of mere sensation, that it should enter
our head and reconstruct a duplicate of itself as it was outside. For
what a poverty-stricken thing is this mere sensation! Even in the
noblest organs of sense it is nothing more than a local and specific
feeling, susceptible within its kind of a few variations, but always
strictly subjective and containing in itself nothing objective,
nothing resembling a perception. For sensation of every sort is and
remains a process in the organism itself. As such it is limited to
the territory inside the skin and can never, accordingly, _per se_
contain anything that lies outside the skin or outside ourselves....
Only when the Understanding ... is roused to activity and brings its
sole and only form, the _law of Causality_, into play, only then does
the mighty transformation take place which makes out of subjective
sensation objective intuition. The Understanding, namely, grasps by
means of its innate, _a priori_, ante-experiential form, the given
sensation of the body as an _effect_ which as such must necessarily
have a _cause_. At the same time the Understanding summons to its aid
the form of the outer sense which similarly lies already preformed in
the intellect (or brain), and which is Space, in order to locate that
cause outside of the organism.... In this process the Understanding,
as I shall soon show, takes note of the most minute peculiarities
of the given sensation in order to construct in the outer space a
cause which shall completely account for them. This operation of the
Understanding is, however, not one that takes place discursively,
reflectively, _in abstracto_, by means of words and concepts; but is
intuitive and immediate.... Thus the Understanding must first create
the objective world; never can the latter, already complete _in
se_, simply promenade into our heads through the senses and organic
apertures. For the senses yield us nothing further than the raw
material which must be first elaborated into the objective conception
of an orderly physical world-system by means of the aforesaid simple
forms of Space, Time, and Causality.... Let me show the great chasm
between sensation and perception by showing how raw the material is
out of which the fair structure is upreared. Only two senses serve
objective perception: touch and sight. They alone furnish the data
on the basis whereof the Understanding, by the process indicated,
erects the objective world.... These data in themselves are still
no perception; that is the Understanding's work. If I press with my
hand against the table, the sensation I receive has no analogy with
the idea of the firm cohesion of the parts of this mass: only when my
Understanding passes from the sensation to its cause does it create
for itself a body with the properties of solidity, impenetrability,
and hardness. When in the dark I lay my hand on a surface, or grasp a
ball of three inches diameter, in either case the same parts of the
hand receive the impression: but out of the different contraction of
the hand in the two cases my Understanding constructs the form of the
body whose contact caused the feeling, and confirms its construction
by leading me to move my hand over the body. If one born blind
handles a cubical body, the sensations of his hand are quite uniform
on all sides and in all directions,--only the corners press upon a
smaller part of his skin. In these sensations, as such, there is
nothing whatever analogous to a cube. But from the felt resistance
his Understanding infers immediately and intuitively a cause thereof,
which now presents itself as a solid body; and from the movements
of exploration which the arms made whilst the feelings of the hands
remained constant he constructs, in the space known to him _a priori_,
the body's cubical shape. Did he not bring with him ready-made the
idea of a cause and of a space, with the laws thereof, there never
could arise, out of those successive feelings in his hand, the
image of a cube. If we let a string run through our closed hand, we
immediately construct as the cause of the friction and its duration in
such an attitude of the hand, a long cylindrical body moving uniformly
in one direction. But never out of the pure sensation in the hand
could the idea of movement, that is, of change of position in space
by means of time, arise: such a content can never lie in sensation,
nor come out of it. Our Intellect, antecedently to all experience,
must bear in itself the intuitions of Space and Time, and therewithal
of the possibility of motion, and no less the idea of Causality, to
pass from the empirically given feeling to its cause, and to construct
the latter as a so moving body of the designated shape. For how great
is the abyss between the mere sensation in the hand and the ideas
of causality, materiality, and movement through Space, occurring
in Time! The feeling in the hand, even with different contacts and
positions, is something far too uniform and poor in content for it
to be possible to construct out of _it_ the idea of Space with its
three dimensions, of the action of bodies on each other, with the
properties of extension, impenetrability, cohesion, shape, hardness,
softness, rest, and motion--in short, the foundations of the objective
world. This is only possible through Space, Time, and Causality ...
being preformed in the Intellect itself,... from whence it again
follows that the perception of the external world is essentially an
intellectual process, a work of the Understanding, _to which sensation
furnishes merely the occasion,_ and the data to be interpreted in each
particular case."[264]

I call this view mythological, because I am conscious of no such Kantian machine-shop in my mind, and feel no call to disparage the powers of poor sensation in this merciless way. I have no introspective experience of mentally producing or creating space. My space-intuitions occur not in two times but in one. There is not one moment of passive inextensive sensation, succeeded by another of active extensive perception, but the form I see is as immediately felt as the color which fills it out. That the higher parts of the mind come in, who can deny? They add and subtract, they compare and measure, they reproduce and abstract. They inweave the space-sensations with intellectual relations; but _these_ relations are the same when they obtain between the elements of the space-system as when they obtain between any of the other elements of which the world is made.

The essence of the Kantian contention is that there are not _spaces_, but _Space_--one infinite continuous _Unit_--and that our knowledge of _this_ cannot be a piecemeal sensational affair, produced by summation and abstraction. To which the obvious reply is that, if any known thing bears on its front the _appearance_ of piecemeal construction and abstraction, it is this very notion of the infinite unitary space of the world. It is a _notion_, if ever there was one; and no intuition. Most of us apprehend it in the barest symbolic abridgment: and if perchance we ever do try to make it more adequate, we just add one image of sensible extension to another until we are tired. Most of us are obliged to turn round and drop the thought of the space in front of us when we think of that behind. And the space represented as near to us seems more minutely subdivisible than that we think of as lying far away.

      *       *       *       *       *

The other prominent German writers on space are also 'psychical stimulists.' Herbart, whose influence has been widest, says 'the resting eye sees no space,'[265] and ascribes visual extension to the influence of movements combining with the non-spatial retinal feelings so as to form gradated series of the latter. A given sensation of such a series reproduces the idea of its associates in regular order, and its idea is similarly reproduced by any one of them with the order reversed. Out of the fusion of these two contrasted reproductions comes the form of space[266]--Heaven knows how.

The obvious objection is that mere serial order is a _genus_, and space-order a very peculiar species of that _genus_; and that, if the terms of reversible series became by that fact coexistent terms in space, the musical scale, the degrees of warmth and cold, and all other ideally graded series ought to appear to us in the shape of extended corporeal aggregates,--which they notoriously do not, though we may of course _symbolize_ their order by a spatial scheme. W. Volkmann von Volkmar, the Herbartian, takes the bull here by the horns, and says the musical scale _is_ spatially extended, though he admits that its space does not belong to the real world.[267] I am unacquainted with any other Herbartian so bold.

      *       *       *       *       *

To Lotze we owe the much-used term 'local sign.' He insisted that space could not emigrate directly into the mind from without, but must be _reconstructed_ by the soul; and he seemed to think that the first reconstructions of it by the soul must be super-sensational. But why sensations themselves might not be the soul's _original_ spatial reconstructive acts Lotze fails to explain.

      *       *       *       *       *

Wundt has all his life devoted himself to the elaboration of a space-theory, of which the neatest and most final expression is to be found in his Logik (ii. 457-60). He says:

"In the eye, space-perception has certain constant peculiarities
which prove that no single optical sensation by itself possesses
the extensive form, but that everywhere in our perception of space
heterogeneous feelings combine. If we simply suppose that luminous
sensations _per se_ feel extensive, our supposition is shattered by
that influence of movement in vision which is so clearly to be traced
in many normal errors in the measurement of the field of view. If
we assume, on the other hand, that the movements and their feelings
are alone possessed of the extensive quality, we make an unjustified
hypothesis, for the phenomena compel us, it is true, to accord an
influence to movement, but give us no right to call the retinal
sensations indifferent, for there are no visual ideas without retinal
sensations. If then we wish rigorously to express the given facts, we
can ascribe a spatial constitution only to _combinations_ of retinal
sensations with those of movement."

Thus Wundt, dividing theories into 'nativistic' and 'genetic,' calls his own a genetic theory. To distinguish it from other theories of the same class, he names it a 'theory of complex local signs.'

"It supposes two systems of local signs, whose relations--taking the
eye as an example--we may think as ... the measuring of the manifold
local-sign system of the retina by the simple local-sign system of
the movements. In its psychological nature this is a process of
associative synthesis: it consists in the fusion of both groups of
sensations into a product, whose elementary components are no longer
separable from each other in idea. In melting wholly away into the
product which they create they become consciously undistinguishable,
and the mind apprehends only their resultant, the intuition of space.
Thus there obtains a certain analogy between this psychic synthesis
and that chemical synthesis which out of simple bodies generates a
compound that appears to our immediate perception as a homogeneous
whole with new properties."

Now let no modest reader think that if this sounds obscure to him it is because he does not know the full context; and that if a wise professor like Wundt can talk so fluently and plausibly about 'combination' and 'psychic synthesis,' it must surely be because those words convey a so much greater fulness of positive meaning to the scholarly than to the unlearned mind. Really it is quite the reverse; _all_ the virtue of the phrase lies in its mere sound and skin. Learning does but make one the more sensible of its inward unintelligibility. Wundt's 'theory' is the flimsiest thing in the world. It starts by an untrue assumption, and then corrects it by an unmeaning phrase. Retinal sensations _are_ spatial; and were they not, no amount of 'synthesis' with equally spaceless motor sensations could intelligibly make them so. Wundt's theory is, in short, but an avowal of impotence, and an appeal to the inscrutable powers of the soul.[268] It confesses that we cannot analyze the constitution or give the genesis of the spatial quality in consciousness. But at the same time it says the _antecedents_ thereof are psychical and not cerebral facts. In calling the quality in question a _sensational_ quality, our own account equally disclaimed ability to analyze it, but said its antecedents were cerebral, not psychical--in other words, that it was a _first_ psychical thing. This is merely a question of probable fact, which the reader may decide.

      *       *       *       *       *

And now what shall be said of Helmholtz? Can I find fault with a book which, on the whole, I imagine to be one of the four or five greatest monuments of human genius in the scientific line? If truth impels I must fain try, and take the risks. It seems to me that Helmholtz's genius moves most securely when it keeps close to particular facts. At any rate, it shows least strong in purely speculative passages, which in the Optics, in spite of many beauties, seem to me fundamentally vacillating and obscure. The 'empiristic' view which Helmholtz defends is that the space-determinations we perceive are in every case products of a process of unconscious inference.[269] The inference is similar to one from induction or analogy.[270] We always see that form before us which _habitually_ would have caused the sensation we now have.[271] But the latter sensation can never be intrinsically spatial, or its intrinsic space-determinations would never be overcome as they are so often by the 'illusory' space-determinations it so often suggests.[272] Since the illusory determination can be traced to a suggestion of Experience, the 'real' one must also be such a suggestion: so that _all_ space intuitions are due solely to Experience.[273] The only psychic activity required for this is the association of ideas.[274]

But how, it may be asked, can association produce a space-quality not in the things associated? How can we by induction or analogy infer what we do not already generically know? Can 'suggestions of experience' reproduce elements which no particular experience originally contained? This is the point by which Helmholtz's 'empiristic' theory, as a _theory_, must be judged. No theory is worthy of the name which leaves such a point obscure.

Well, Helmholtz does so leave it. At one time he seems to fall back on inscrutable powers of the soul, and to range himself with the 'psychical stimulists.' He speaks of Kant as having made the essential step in the matter in distinguishing the content of experience from that form--space, course--which is given it by the peculiar faculties of the mind.[275] But elsewhere, again,[276] speaking of sensationalistic theories which would connect spatially determinate feelings _directly_ with certain neural events, he says it is better to assume only such simple psychic activities as we _know_ to exist, and gives the association of ideas as an instance of what he means. Later,[277] he reinforces this remark by confessing that he does not see how any neural process _can_ give rise without antecedent experience to a ready-made (_fertige_) perception of space. And, finally, in a single momentous sentence, he speaks of sensations of _touch_ as if they might be the original material of our space-percepts--which thus, from the optical point of view, 'may be assumed as _given_.'[278]

Of course the eye-man has a right to fall back on the skin-man for help at a pinch. But doesn't this mean that he is a mere eye-man and not a complete psychologist? In other words, Helmholtz's Optics and the 'empiristic theory' therein professed must not be understood as attempts at answering the _general_ question of how space-consciousness enters the mind. They simply deny that it enters with the first optical sensations.[279] Our own account has affirmed stoutly that it enters _then_; but no more than Helmholtz have we pretended to show _why_. Who calls a thing a first sensation admits he has no theory of its production. Helmholtz, though all the while without an articulate theory, makes the world think he has one. He beautifully traces the immense part which reproductive processes play in our vision of space, and never--except in that one pitiful little sentence about touch--does he tell us just what it is they reproduce. He limits himself to denying that they reproduce originals of a visual sort. And so difficult is the subject, and so magically do catch-words work on the popular-scientist ear, that most likely, had he written 'physiological' instead of 'nativistic,' and 'spiritualistic' instead of 'empiristic' (which synonyms Hering suggests), numbers of his present empirical evolutionary followers would fail to find in his teaching anything worthy of praise. But since he wrote otherwise, they hurrah for him as a sort of second Locke, dealing another death-blow at the old bugaboo of 'innate ideas.' His 'nativistic' adversary Hering they probably imagine--Heaven save the mark!--to be a scholastic in modern disguise.

      *       *       *       *       *

After Wundt and Helmholtz, the most important anti-sensationalist space-philosopher in Germany is Professor Lipps, whose deduction of space from an order of non-spatial differences, continuous yet separate, is a wonderful piece of subtlety and logic. And yet he has to confess that continuous differences form in the first instance only a logical series, which _need_ not appear spatial, and that wherever it does so appear, this must be accounted a 'fact,' due merely 'to the nature of the soul.'[280]

Lipps, and almost all the anti-sensationalist theorists except Helmholtz, seem guilty of that confusion which Mr. Shadworth Hodgson has done so much to clear away, viz., the confounding the analysis of an idea with the means of its production. Lipps, for example, finds that every space we think of can be broken up into positions, and concludes that in some undefined way the several positions must have pre-existed in thought before the aggregate space could have appeared to perception. Similarly Mr. Spencer, defining extension as an 'aggregate of relations of coexistent position,' says "every cognition of magnitude is a cognition of relations of position,"[281] and "no idea of extension can arise from the simultaneous excitation" of many nerves "unless there is a knowledge of their relative positions."[282] Just so Prof. Bain insists that the very _meaning_ of space is scope for movement,[283] and that therefore distance and magnitude _can_ be no original attributes of the eye's sensibility. Similarly because movement is analyzable into positions occupied at successive moments by the mover, philosophers (e.g. Schopenhauer, as quoted above) have repeatedly denied the possibility of _its_ being an immediate sensation. We have, however, seen that it is the most immediate of all our space-sensations. Because it can only occur in a definite direction the impossibility of perceiving it without perceiving its direction has been decreed--a decree which the simplest experiment overthrows.[284] It is a case of what I have called the 'psychologist's fallacy': mere acquaintance with space is treated as tantamount to every sort of knowledge about it, the conditions of the latter are demanded of the former state of mind, and all sorts of mythological processes are brought in to help.[285] As well might one say that because the world consists of all its parts, therefore we can only apprehend it at all by having unconsciously summed these up in our head. It is the old idea of our actual knowledge being drawn out from a pre-existent potentiality, an idea which, whatever worth it may metaphysically possess, does no good in psychology.

My own sensationalistic account has derived most aid and comfort from the writings of Hering, A. W. Volkmann, Stumpf, Le Conte, and Schön. All these authors allow ample scope to that Experience which Berkeley's genius saw to be a present factor in all our visual acts. But they give Experience some grist to grind, which the _soi-distant_ 'empiristic' school forgets to do. Stumpf seems to me the most philosophical and profound of all these writers; and I owe him much. I should doubtless have owed almost as much to Mr. James Ward, had his article on Psychology in the Encyclopædia Britannica appeared before my own thoughts were written down. The literature of the question is in all languages very voluminous. I content myself with referring to the bibliography in Helmholtz's and Aubert's works on Physiological Optics for the visual part of the subject, and with naming in a note the ablest works in the English tongue which have treated of the subject in a _general_ way.[286]

      *       *       *       *       *

[140] Reprinted, with considerable revision, from 'Mind' for 1887.

[141] Prof. Jastrow has found that invariably we tend to _underestimate_ the amount of our skin which may be stimulated by contact with an object when we express it in terms of visual space; that is, when asked to mark on paper the extent of skin affected, we always draw it much too small. This shows that the eye gets as much space feeling from the smaller line as the skin gets from the larger one. Cf. Jastrow: Mind, xi. 546-7; American Journal of Psychology, iii. 53.

[142] Amongst sounds the graver ones seem the most extensive. Stumpf gives three reasons for this: 1) association with bigger causes; 2) wider reverberation of the hand and body when grave notes are sung; 3) audibility at a greater distance. He thinks that these three reasons dispense us from supposing an immanent extensity in the sensation of sound as such. See his remarks in the Tonpsychologie, i. 207-211.

[143] Encyclopædia Britannica, 9th Edition, article Psychology, pp. 46, 58.

[144] Philosophical Transactions (1841).

[145] Hermann's Handb. d. Physiol., Bd. iii. 1, §. 575.

[146] _Loc. cit._ §. 572.

[147] Elemente der Psychophysik, ii. 475-6.

[148] See Foster's Text-book of Physiology, bk. iii. c. vi. § 2.

[149] Fechner, who was ignorant of the but lately discovered function of the semi-circular canals, gives a different explanation of the organic seat of these feelings. They are probably highly composite. With me, actual movements in the eyes play a considerable part in them, though I am hardly conscious of the peculiar feelings in the scalp which Fechner goes on to describe thus: "The feeling of strained attention in the different sense-organs seems to be only a muscular one produced in using these various organs by setting in motion, by a sort of reflex action, the set of muscles which belong to them. One can ask, then, with what particular muscular contraction the sense of strained attention in the effort to recall something is associated? On this question my own feeling gives me a decided answer; it comes to me distinctly not as a sensation of tension in the inside of the head, but as a feeling of strain and contraction in the scalp, with a pressure from outwards in over the whole cranium, undoubtedly caused by a contraction of the muscles of the scalp. This harmonizes very well with the expressions, _sich den Kopf zerbrechen, den Kopf zusammennehmen_. In a former illness, when I could not endure the slightest effort after continuous thought, and had no theoretical bias on this question, the muscles of the scalp, especially those of the back-head, assumed a fairly morbid degree of sensibility whenever I tried to think." (Elem. der Psychophysik, ii, 490-91.)

[150] That the sensation in question is one of tactile rather than of acoustic sensibility would seem proved by the fact that a medical friend of the writer, both of whose _membranæ tympani_ are quite normal, but one of whose ears is almost totally deaf, feels the presence and withdrawal of objects as well at one ear as at the other.

[151] The skin seems to obey a different law from the eye here. If a given retinal tract be excited, first by a series of points, and next by the two extreme points, with the interval between them unexcited, this interval will seem considerably less in the second case than it seemed in the first. In the skin the unexcited interval feels the larger. The reader may easily verify the facts in this case by taking a visiting-card, cutting one edge of it into a saw-tooth pattern, and from the opposite edge cutting out all but the two corners, and then comparing the feelings aroused by the two edges when held against the skin.

[152] Classen, Physiologie des Gesichtssinnes, p. 114; see also A. Riehl, Der Philosophische Kriticismus, ii. p. 149.

[153] It is worth while at this point to call attention with some emphasis to the fact that, though the anatomical condition of the feeling _resembles_ the feeling itself, such resemblance cannot be taken by our understanding to explain _why_ the feeling should be just what it is. We hear it untiringly reiterated by materialists and spiritualists alike that we can see no possible inward reason why a certain brain-process should produce the feeling of redness and another of anger: the one process is no more red than the other is angry, and the coupling of process and feeling is, as far as our understanding goes, a juxtaposition pure and simple. But in the matter of _spatial_ feeling, where the retinal patch that produces a triangle in the mind is itself a triangle, etc., it looks at first sight as if the sensation might be a direct cognition of its own neural condition. Were this true, however, our sensation should be one of _multitude_ rather than of continuous extent; for the condition is _number_ of optical nerve-termini, and even this is only a remote condition and not an immediate condition. The immediate condition of the feeling is not the process in the retina, but the process in the brain; and the process in the brain may, for aught we know, be as unlike a triangle,--nay, it probably is so,--as it is unlike redness or rage. It is simply a _coincidence_ that in the case of space one of the organic conditions, viz., the triangle impressed on the skin or the retina, should lead to a representation in the mind of the subject observed similar to that which it produces in the psychological observer. In no other kind of case is the coincidence found. Even should we admit that we cognize triangles in space because of our immediate cognition of the triangular shape of our excited group of nerve-tips, the matter would hardly be more transparent, for the mystery would still remain, why are we so much better cognizant of triangles on our finger-tips than on the nerve-tips of our back, on our eye than on our ear, and on any of these parts than in our brain? Thos. Brown very rightly rejects the notion of explaining the shape of the space perceived by the shape of the 'nervous expansion affected.' "If this alone were necessary, we should have square inches and half inches, and various other forms, rectilinear and curvilinear, of fragrance and sound." (Lectures, XXII.)

[154] Musical tones, e.g., have an order of quality independent either of their space- or time-order. Music comes from the time-order of the notes upsetting their quality-order. In general, if _a b c d e f g h i j k_, etc., stand for an arrangement of feelings in the order of their quality, they may assume _any_ space-order or time-order, as _d e f a h g_, etc., and still the order of quality will remain fixed and unchanged.

[155] The whole science of geometry may be said to owe its being to the exorbitant interest which the human mind takes in _lines_. We cut space up in every direction in order to manufacture them.

[156] Kant was, I believe, the first to call attention to this last order of facts. After pointing out that two opposite spherical triangles, two gloves of a pair, two spirals wound in contrary directions, have identical inward determinations, that is, have their parts defined with relation _to each other_ by the same law, and so must be _conceived_ as identical, he showed that the impossibility of their mutual superposition obliges us to assign to each figure of a symmetrical pair a peculiar difference of its own which can only consist in an _outward_ determination or relation of its parts, no longer to each other, but to the whole of an objectively outlying space with its points of the compass given absolutely. This in_con_ceivable difference is perceived only "through the relation to right and left, which is a matter of immediate intuition." In these last words (_welches unmittelbar auf Anschauung geht_--Prolegomena, § 12) Kant expresses all that we have meant by speaking of up and down, right and left, as _sensations_. He is wrong, however, in invoking relation to extrinsic total space as essential to the existence of these contrasts in figures. Relation to our own body is enough.

[157] In the eyes of many it will have seemed strange to call a relation a mere line, and a line a mere sensation. We may easily learn a great deal _about_ any relation, say that between two points: we may divide the line which joins these, and distinguish it, and classify it, and find out _its_ relations by drawing or representing new lines, and so on. But all this further industry has naught to do with our _acquaintance_ with the relation itself, in its first intention. So cognized, the relation _is_ the line and nothing more. It would indeed be fair to call it something less; and in fact it is easy to understand how most of us come to feel as if the line were a much grosser thing than the relation. The line is broad or narrow, blue or red, made by this object or by that alternately, in the course of our experience; it is therefore independent of any one of these accidents; and so, from viewing it as no one of _such_ sensible qualities, we may end by thinking of it as something which cannot be defined except as the negation of all sensible quality whatever, and which needs to be put _into_ the sensations by a mysterious act of 'relating thought.'

Another reason why we get to feel as if a space-relation must be something other than the mere feeling of a line or angle is that between two positions we can potentially make any number of lines and angles, or find, to suit our purposes, endlessly numerous relations. The sense of this indefinite potentiality cleaves to our words when we speak in a general way of 'relations of place,' and misleads us into supposing that not even any single one of them can be exhaustively equated by a single angle or a single line.

[158] This often happens when the warm and cold points, or the round and pointed ones, are applied to the skin within the limits of a single 'Empfindungskreis.'

[159] Vierordt, Grundriss der Physiologie, 5te Auflage (1877), pp. 326, 436.

[160] Vorlesungen üb. Menschen- u. Thierseele (Leipzig, 1863), i. 214. See also Ladd's Physiological Psychology, pp. 396-8, and compare the account by G. Stanley Hall (Mind, x. 571) of the sensations produced by moving a blunt point lightly over the skin. Points of cutting pain, quivering, thrilling, whirling, tickling, scratching, and acceleration, alternated with each other along the surface.

[161] Of the anatomical and physiological conditions of these facts we know as yet but little, and that little need not here be discussed. Two principal hypotheses have been invoked in the case of the retina. Wundt (Menschen- u. Thierseele, i. 214) called attention to the changes of color-sensibility which the retina displays as the image of the colored object passes from the fovea to the periphery. The color alters and becomes darker, and the change is more rapid in certain directions than in others. This alteration in general, however, is one of which, _as such_, we are wholly unconscious. We see the sky as bright blue all over, the modifications of the blue sensation being interpreted by us, not as differences in the objective color, but as distinctions in its locality. Lotze (Medizinische Psychologie, 333, 355), on the other hand, has pointed out the peculiar tendency which each particular point of the retina has to call forth that movement of the eyeball which will carry the image of the exciting object from the point in question to the _fovea_. With each separate tendency to movement (as with each actual movement) we may suppose a peculiar modification of sensibility to be conjoined. This modification would constitute the peculiar local tingeing of the image by each point. See also Sully's Psychology, pp. 118-121. Prof. B. Erdman has quite lately (Vierteljahrsschrift f. wiss. Phil., x. 324-9) denied the existence of all evidence for such immanent _qualia_ of feeling characterizing each locality. Acute as his remarks are, they quite fail to convince me. On the skin the _qualia_ are evident, I should say. Where, as on the retina, they are less so (Kries and Auerbach), this may well be a mere difficulty of discrimination not yet educated to the analysis.

[162] 1852, p. 331.

[163] Maybe the localization of intracranial pain is itself due to such association as this of local signs with each other, rather than to their qualitative similarity in neighboring parts (_supra_, p. 19); though it is conceivable that association and similarity itself should here have one and the same neural basis. If we suppose the sensory nerves from those parts of the body beneath any patch of skin to terminate in the same sensorial brain-tract as those from the skin itself, and if the excitement of any one fibre tends to irradiate through the whole of that tract, the feelings of all fibres going to that tract would presumably both have a similar intrinsic quality, and at the same time tend each to arouse the other. Since the same nerve-trunk in most cases supplies the skin and the parts beneath, the anatomical hypothesis presents nothing improbable.

[164] Unless, indeed, the foot happen to be spontaneously tingling or something of the sort at the moment. The whole surface of the body is always in a state of semi-conscious irritation which needs only the emphasis of attention, or of some accidental inward irritation, to become strong at any point.

[165] It is true that the inside of the forearm, though its discriminative sensibility is often less than that of the outside, usually rises very prominently into consciousness when the latter is touched. Its _æsthetic_ sensibility to contact is a good deal finer. We enjoy stroking it from the extensor to the flexor surface around the ulnar side more than in the reverse direction. Pronating movements give rise to contacts in this order, and are frequently indulged in when the back of the forearm feels an object against it.

[166] These facts were first noticed by Wundt: see his Beiträge, p. 140, 202. See also Lamansky, Pflüger's Archiv, xi. 418.

[167] So far all has been plain sailing, but our course begins to be so tortuous when we descend into minuter detail that I will treat of the more precise determination of locality in a long note. When _P_ recalls an ideal line leading to the fovea the line is felt in its entirety and but vaguely; whilst _P_, which we supposed to be a single star of actual light, stands out in strong distinction from it. The ground of the distinction between _P_ and the ideal line which it terminates is manifest--_P_ being vivid while the line is faint; _but why should P hold the particular position it does, at the end of the line, rather than anywhere else--for example, in its middle?_ That seems something not at all manifest.

To clear up our thoughts about this latter mystery, let us take the case of an actual line of light, none of whose parts is ideal. The feeling of the line is produced, as we know, when a multitude of retinal points are excited together, each of which _when excited separately_ would give rise to _one_ of the feelings called local signs. Each of these signs is the feeling of a small space. From their simultaneous arousal we might well suppose a feeling of larger space to result. But why is it necessary that _in_ this larger spaciousness the sign _a_ should appear always at one end of the line, _z_ at the other, and _m_ in the middle? For though the line be a unitary streak of light, its several constituent points can nevertheless break out from it, and become alive, each for itself, under the selective eye of attention.

The uncritical reader, giving his first careless glance at the subject, will say that there is no mystery in this, and that 'of course' local signs must appear alongside of each other, each in its own place;--there is no other way possible. But the more philosophic student, whose business it is to discover difficulties quite as much as to get rid of them, will reflect that it is conceivable that the partial factors might fuse into a larger space, and yet not each be located within it any more than a voice is _located_ in a chorus. He will wonder how, after combining into the line, the points _can_ become severally alive again: the separate puffs of a 'sirene' no longer strike the ear after they have fused into a certain pitch of sound. He will recall the fact that when, after looking at things with one eye closed, we double, by opening the other eye, the number of retinal points affected, the new retinal sensations do not as a rule appear _alongside_ of the old ones and additional to them, but merely make the old ones seem larger and nearer. Why should the affection of new points on the _same_ retina have so different a result? In fact, he will see no sort of logical connection between (1) the original separate local signs, (2) the line as a unit, (3) the line with the points discriminated in it, and (4) the various nerve-processes which subserve all these different things. He will suspect our local sign of being a very slippery and ambiguous sort of creature. Positionless at first, it no sooner appears in the midst of a gang of companions than it is found maintaining the strictest position of its own, and assigning place to each of its associates. How is this possible? Must we accept what we rejected a while ago as absurd, and admit the points each to have position _in se_? Or must we suspect that our whole construction has been fallacious, and that we have tried to conjure up, out of association, qualities which the associates never contained?

There is no doubt a real difficulty here; and the shortest way of dealing with it would be to confess it insoluble and ultimate. Even if position be not an intrinsic character of any one of those sensations we have called local signs, we must still admit that there is _something about_ every one of them that stands for the potentiality of position, and is the _ground_ why the local sign, when it gets placed at all, gets placed _here_ rather than _there_. If this 'something' be interpreted as a physiological something, as a mere nerve-process, it is easy to say in a blank way that when it is excited alone, it is an 'ultimate fact' (1) that a positionless spot will appear; that when it is excited together with other similar processes, but _without_ the process of discriminative attention, it is another 'ultimate fact' (2) that a unitary line will come; and that the final 'ultimate fact' (3) is that, when the nerve-process is excited _in combination with_ that other process which subserves the feeling of attention, what results will be the line with the local sign inside of it determined to a particular place. Thus we should escape the responsibility of explaining, by falling back on the everlasting inscrutability of the psycho-neural nexus. The moment we call the ground of localization physiological, we need only point out _how_, in those cases in which localization occurs, the physiological process _differs_ from those in which it does not, to have done all we can possibly do in the matter. This would be unexceptionable logic, and with it we might let the matter drop, satisfied that there was no self-contradiction in it, but only the universal psychological puzzle of how a new mode of consciousness emerges whenever a fundamentally new mode of nervous action occurs.

But, blameless as such tactics would logically be on our part, let us see whether we cannot push our theoretic insight a little farther. It seems to me we can. We cannot, it is true, give a reason why the line we feel when process (2) awakens should have its own peculiar shape; nor can we explain the essence of the process of discriminative attention. But we can see why, if the brute facts be admitted that a line may have one of its parts singled out by attention at all, and that that part may appear in relation to other parts at all, the relation must be _in the line itself_,--for the line and the parts are the only things supposed to be in consciousness. And we can furthermore suggest a reason why parts appearing thus in relation to each other in a line should fall into an immutable order, and each within that order keep its characteristic place.

If a lot of such local signs all have any quality which evenly augments as we pass from one to the other, we can arrange them in an ideal serial order, in which any one local sign must lie below those with more, above those with less, of the quality in question. It must divide the series into two parts,--unless indeed it have a maximum or minimum of the quality, when it either begins or ends it.

Such an ideal series of local signs in the mind is, however, not yet identical with the feeling of a line in space. Touch a dozen points on the skin _successively_, and there seems no necessary reason why the notion of a definite line should emerge, even though we be strongly aware of a gradation of quality among the touches. We may of course symbolically arrange them in a line in our thought, but we can always distinguish between a line symbolically thought and a line directly felt.

But note now the peculiarity of the nerve-processes of all these local signs: though they may give no line when excited successively, when excited _together_ they do give the actual sensation of a line in space. The sum of them is the neural process of that line; the sum of their feelings is the feeling of that line; and if we begin to single out particular points from the line, and notice them by their rank, it is impossible to see how this rank can _appear_ except as an actual fixed space-position sensibly felt as a bit of the total line. The scale itself appearing as a line, rank in it must appear as a definite part of the line. If the seven notes of an octave, when heard together, appeared to the sense of hearing as an outspread _line_ of sound--which it is needless to say they do not--why then no one note could be discriminated without being localized, according to its pitch, _in_ the line, either as one of its extremities or as some part between.

But not alone the gradation of their quality arranges the local-sign feelings in a scale. Our _movements_ arrange them also in a time-scale. Whenever a stimulus passes from point _a_ of the skin or retina to point _f_, it awakens the local-sign feelings in the perfectly definite time-order _abcdef_. It cannot excite _f_ until _cde_ have been successively aroused. The feeling _c_ sometimes is preceded by _ab_, sometimes followed by _ba_, according to the movement's direction; the result of it all being that we never feel either _a, c,_ or _f_, without there clinging to it faint reverberations of the various time-orders of transition in which, throughout past experience, it has been aroused. To the local sign _a_ there clings the tinge or tone, the penumbra or fringe, of the transition _bcd_. To _f_, to _c_, there cling quite different tones. Once admit the principle that a feeling may be tinged by the reproductive consciousness of an habitual transition, even when the transition is not made, and it seems entirely natural to admit that, if the transition be habitually in the order _abcdef_, and if _a, c,_ and _f_ be felt separately at all, _a_ will be felt with an essential _earliness_, _f_ with an essential _lateness_, and that _c_ will fall between. Thus those psychologists who set little store by local signs and great store by movements in explaining space-perception, would have a perfectly definite time-order, due to motion, by which to account for the definite order of positions that appears when sensitive spots are excited all at once. Without, however, the preliminary admission of the 'ultimate fact' that this collective excitement shall feel like a _line_ and nothing else, it can never be explained why the new order should needs be an order of _positions_, and not of merely ideal serial rank. We shall hereafter have any amount of opportunity to observe how thoroughgoing is the participation of motion in all our spatial measurements. Whether the local signs have their respective qualities evenly graduated or not, the feelings of transition must be set down as among the _veræ causæ_ in localization. But the gradation of the local signs is hardly to be doubted; so we may believe ourselves really to possess two sets of reasons for localizing any point we may happen to distinguish from out the midst of any line or any larger space.

[168] M. Binet (Revue Philosophique, Sept. 1880, page 291) says we judge them locally different as soon as their sensations differ enough for us to distinguish them as qualitatively different when successively excited. This is not strictly true. Skin-sensations, different enough to be discriminated when _successive_, may still fuse locally if excited both at once.

[169] It may, however, be said that even in the tongue there is a determination of bitter flavors to the back and of acids to the front edge of the organ. Spices likewise affect its sides and front, and a taste like that of alum localizes itself, by its styptic effect on the portion of mucous membrane, which it immediately touches, more sharply than roast pork, for example, which stimulates all parts alike. The pork, therefore, tastes more spacious than the alum or the pepper. In the nose, too, certain smells, of which vinegar may be taken as the type, seem less spatially extended than heavy, suffocating odors, like musk. The reason of this appears to be that the former inhibit inspiration by their sharpness, whilst the latter are drawn into the lungs, and thus excite an objectively larger surface. The ascription of height and depth to certain notes seems due, not to any localization of the sounds, but to the fact that a feeling of vibration in the chest and tension in the gullet accompanies the singing of a bass note, whilst, when we sing high, the palatine mucous membrane is drawn upon by the muscles which move the larynx, and awakens a feeling in the roof of the mouth.

The only real objection to the law of partial stimulation laid down in the text is one that might be drawn from the organ of hearing; for, according to modern theories, the cochlea may have its separate nerve-termini exclusively excited by sounds of differing pitch, and yet the sounds seem all to fill a common space, and not necessarily to be arranged alongside of each other. At most the high note is felt as a thinner, brighter streak against a darker background. In an article on Space, published in the Journal of Speculative Philosophy for January, 1879, I ventured to suggest that possibly the auditory nerve termini might be "excited all at once by sounds of any pitch, as the whole retina would be by every luminous point if there were no dioptric apparatus affixed." And I added: "Notwithstanding the brilliant conjectures of the last few years which assign different acoustic end-organs to different rates of air-wave, we are still greatly in the dark about the subject; and I, for my part, would much more confidently reject a theory of hearing which violated the principles advanced in this article than give up those principles for the sake of any hypothesis hitherto published about either organs of Corti or basilar membrane." Professor Rutherford's theory of hearing, advanced at the meeting of the British Association for 1886, already furnishes an alternative view which would make hearing present no exception to the space-theory I defend and which, whether destined to be proved true or false, ought, at any rate to make us feel that the Helmholtzian theory is probably not the last word in the physiology of hearing. Stepano, ff. (Hermann und Schwalbe's Jahresbericht, xv. 404, Literature 1886) reports a case in which more than the upper half of one cochlea was lost without any such deafness to deep notes on that side as Helmholtz's theory would require.

[170] Donaldson, in Mind, x. 399, 577; Goldscheider, in Archiv f. (Anat. u.) Physiologie; Blix, in Zeitschrift für Biologie. A good résumé may be found in Ladd's Physiol. Psychology, part ii. chap. iv. §§ 21-23.

[171] I tried on nine or ten people, making numerous observations on each, what difference it made in the discrimination of two points to have them alike or unlike. The points chosen were (1) two large needle-heads, (2) two screw-heads, and (3) a needle-head and a screw-head. The distance of the screw-heads was measured from their centres. I found that when the points gave diverse qualities of feeling (as in 3), this facilitated the discrimination, but much less strongly than I expected. The difference, in fact, would often not be perceptible twenty times running. When, however, one of the points was endowed with a rotary movement, the other remaining still, the doubleness of the points became much more evident than before. To observe this I took an ordinary pair of compasses with one point blunt, and the movable leg replaced by a metallic rod which could, at any moment, be made to rotate _in situ_ by a dentist's drilling-machine, to which it was attached. The compass had then its points applied to the skin at such a distance apart as to be felt as one impression. Suddenly rotating the drill-apparatus then almost always made them seem as two.

[172] This is only another example of what I call 'the psychologist's fallacy'--thinking that the mind he is studying must necessarily be conscious of the object after the fashion in which the psychologist himself is conscious of it.

[173] Sitzb. der. k. Akad. Wien, Bd. lxxii., Abth. 8 (1875).

[174] Zeitschrift für Biologie, xii. 226 (1876).

[175] Vierteljahrsch. für wiss. Philos., ii. 377.

[176] Exner tries to show that the structure of the faceted eye of articulates adapts it for perceiving motions almost exclusively.

[177] Schneider tries to explain why a sensory surface is so much more excited when its impression moves. It has long since been noticed how much more acute is discrimination of successive than of simultaneous differences. But in the case of a moving impression, say on the retina, we have a summation of both sorts of difference; whereof the natural effect must be to produce the most perfect discrimination of all.

[Illustration: FIG. 53.]

In the left-hand figure let the dark spot B move, for example, from right to left. At the outset there is the simultaneous contrast of black and white in B and A. When the motion has occurred so that the right-hand figure is produced, the same contrast remains, the black and the white having changed places. But in addition to it there is a double successive contrast, first in A, which, a moment ago white, has now become black; and second in B, which, a moment ago black, has now become white. If we make each single feeling of contrast = 1 (a supposition far too favorable to the state of rest), the sum of contrasts in the case of motion will be 3, as against 1 in the state of rest. That is, our attention will be called by a treble force to the difference of color, provided the color begin to move.--(Cf. also Fleischl, Physiologische Optische Notizen, 2te Mittheilung, Wiener Sitzungsberichte, 1882.)

[178] Brown, Bain, J. S. Mill, and in a modified manner Wundt, Helmholtz, Sully, etc.

[179] M. Ch. Dunan, in his forcibly written essay 'l'Espace Visuel et l'Espace Tactile' in the Revue Philosophique for 1888, endeavors to prove that surfaces alone give no perception of extent, by citing the way in which the blind go to work to gain an idea of an object's shape. If surfaces were the percipient organ, he says, "both the seeing and the blind ought to gain an exact idea of the size (and shape) of an object by merely laying their hand flat upon it (provided of course that it were smaller than the hand), and this because of their direct appreciation of the amount of tactile surface affected, and with no recourse to the muscular sense.... But the fact is that a person born blind never proceeds in this way to measure objective surfaces. The only means which he has of getting at the size of a body is that of running his finger along the lines by which it is bounded. For instance, if you put into the hands of one born blind a book whose dimensions are unknown to him, he will begin by resting it against his chest so as to hold it horizontal; then, bringing his two hands together at the middle of the edge opposite to the one against his body, he will draw them asunder till they reach the ends of the edge in question; and then, and not till then, will he be able to say what the length of the object is" (vol. xxv. p. 148). I think that anyone who will try to appreciate the size and shape of an object by simply 'laying his hand flat upon it' will find that the great obstacle is that he _feels the contours_ so imperfectly. The moment, however, the hands move, the contours are emphatically and distinctly felt. All perception of shape and size is perception of contours, and first of all these must be made _sharp_. Motion does this; and the impulse to move our organs in perception is primarily due to the craving which we feel to get our surface-sensations sharp. When it comes to the naming and measuring of objects in terms of some common standard we shall see presently how movements help also; but no more in this case than the other do they help, because the quality of extension itself is contributed by the 'muscular sense.'

[180] Fechner describes (Psychophysik, i. 132) a 'method of equivalents' for measuring the sensibility of the skin. Two compasses are used, one on the part A, another on the part B, of the surface. The points on B must be adjusted so that their distance apart appears equal to that between the points on A. With the place A constant, the second pair of points must be varied a great deal for every change in the place B, though for the same A and B the relation of the two compasses is remarkably constant, and continues unaltered for months, provided but few experiments are made on each day. If, however, we practise daily their difference grows less, in accordance with the law given in the text.

[181] Prof. Jastrow gives as the result of his experiments this general conclusion (Am. Journal of Psychology, iii. 53): "The space-perceptions of disparate senses are themselves disparate, and whatever harmony there is amongst them we are warranted in regarding as the result of experience. The spacial notions of one deprived of the sense of sight and reduced to the use of the other space-senses must indeed be different from our own." But he continues: "The existence of the striking disparities between our visual and our other space-perceptions without confusing us, and, indeed, without usually being noticed, can only be explained by the tendency to interpret all dimensions _into their visual equivalents_." But this author gives no reasons for saying 'visual' rather than 'tactile;' and I must continue to think that probabilities point the other way so far as what we call real magnitudes are concerned.

[182] Cf. Lipps on 'Complication,' Grundtatsachen, etc., p. 579.

[183] Ventriloquism shows this very prettily. The ventriloquist talks without moving his lips, and at the same time draws our attention to a doll, a box, or some other object. We forthwith locate the voice within this object. On the stage an actor ignorant of music sometimes has to sing, or play on the guitar or violin. He goes through the _motions_ before our eyes, whilst in the orchestra or elsewhere the music is performed. But because as we listen we see the actor, it is almost impossible not to _hear_ the music as if coming from where he sits or stands.

[184] Cf. Shand, in Mind, xiii. 340.

[185] See, e.g., Bain's Senses and Intellect, pp. 366-7, 371.

[186] When, for example, a baby looks at its own moving hand, it sees one object at the same time that it feels another. Both interest its attention, and it locates them together. But the felt object's size is the more constant size, just as the felt object is, on the whole, the more interesting and important object; and so the retinal sensations become regarded as its signs and have their 'real space-values' interpreted in tangible terms.

[187] The incoherence of the different primordial sense-spaces _inter se_ is often made a pretext for denying to the primitive bodily feelings any spatial quality at all. Nothing is commoner than to hear it said: "Babies have originally no spatial perception; for when a baby's toe aches he does not place the pain in the toe. He makes no definite movements of defence, and may be vaccinated without being held." The facts are true enough; but the interpretation is all wrong. What really happens is that _the baby does not place his 'toe' in the pain_; for he knows nothing of his 'toe' as yet. He has not attended to it as a visual object; he has not handled it with his fingers; nor have its normal organic sensations or contacts yet become interesting enough to be discriminated from the whole massive feeling of the foot, or even of the leg to which it belongs. In short, the toe is neither a member of the babe's optical space, of his hand-movement space, nor an independent member of his leg-and-foot space. It has actually no mental existence yet save as this little pain-space. What wonder, then, if the pain seem a little space-world all by itself? But let the pain once associate itself with these other space-worlds, and its space will become part of their space. Let the baby feel the nurse stroking the limb and awakening the pain every time her finger passes towards the toe; let him look on and see her finger on the toe every time the pain shoots up; let him handle his foot himself and get the pain whenever the toe comes into his fingers or his mouth; let moving the leg exacerbate the pain,--and all is changed. The space of the pain becomes identified with that part of each of the other spaces which gets felt when it awakens; and by their identity with _it_ these parts are identified with each other, and grow systematically connected as members of a larger extensive whole.

[188] 'Pourquoi les Sensations visuelles sont elles étendues?' in Revue Philosophique, iv. 167.--As the proofs of this chapter are being corrected, I receive the third 'Heft' of Münsterberg's Beiträge zur Experimentellen Psychologie, in which that vigorous young psychologist reaffirms (if I understand him after so hasty a glance) more radically than ever the doctrine that muscular sensation proper is our one means of measuring extension. Unable to reopen the discussion here, I am in duty bound to call the attention of the reader to Herr M.'s work.

[189] Even if the figure be drawn on a board instead of in the air, the variations of contact on the finger's surface will be much simpler than the peculiarities of the traced figure itself.

[190] See for example Duchenne, Electrisation localisée, pp. 727, 770, Leyden; Virchow's Archiv, Bd. xlvii. (1869).

[191] E.g., Eulenburg, Lehrb. d. Nervenkrankheiten (Berlin), 1878, i. 3.

[192] 'Ueber den Kraftsinn,' Virchow's Archiv, Bd. lxxvii. 134.

[193] Archiv f. (Anat. u) Physiologie (1889), pp. 369, 540.

[194] Direction in its 'first intention,' of course; direction with which so far we merely become _acquainted_, and _about_ which we know nothing save perhaps its difference from another direction a moment ago experienced in the same way!

[195] I have said hardly anything about associations with visual space in the foregoing account, because I wished to represent a process which the blind and the seeing man might equally share. It is to be noticed that the space suggested to the imagination when the joint moves, and projected to the distance of the finger-tip, is not represented as any _specific_ skin-tract. What the seeing man imagines is a visible path; what the blind man imagines is rather a generic image, an abstraction from many skin-spaces whose local signs have neutralized each other, and left nothing but their common vastness behind. We shall see as we go on that this generic abstraction of space-magnitude from the various local peculiarities of feeling which accompanied it when it was for the first time felt, occurs on a considerable scale in the acquired perceptions of blind as well as of seeing men.

[196] The ideal enlargement of a system of sensations by the mind is nothing exceptional. Vision is full of it; and in the manual arts, where a workman gets a tool larger than the one he is accustomed to and has suddenly to adapt all his movements to its scale, or where he has to execute a familiar set of movements in an unnatural position of body; where a piano-player meets an instrument with unusually broad or narrow keys; where a man has to alter the size of his handwriting--we see how promptly the mind multiplies once for all, as it were, the whole series of its operations by a constant factor, and has not to trouble itself after that with further adjustment of the details.

[197] Pflüger's Archiv, xlv. 65.

[198] Untersuchungen im Gebiete der Optik, Leipzig (1863), p. 188.

[199] Problems of Life and Mind, prob. vi. chap. iv. § 45.

[200] Volkmann, _op. cit._ p. 189. Compare also what Hering says of the inability in his own case to make after-images seem to move when he rolls his closed eyes in their sockets; and of the insignificance of his feelings of convergence for the sense of distance (Beiträge zur Physiologie, 1881-2, pp. 31, 141). Helmholtz also allows to the muscles of convergence a very feeble share in producing our sense of the third dimension (Physiologische Optik, 649-59).

[201] Compare Lipps, Psychologische Studien (1885), p. 18, and the other arguments given on pp. 12 to 27. The most plausible reasons _for_ contractions of the eyeball-muscles being admitted as original contributors to the perception of extent, are those of Wundt, Physiologische Psychologie, ii. 96-100. They are drawn from certain constant errors in our estimate of lines and angles; which, however, are susceptible, all of them, of different interpretations (see some of them further on).--Just as my MS. goes to the printer, Herr Münsterberg's Beiträge zur experimentellen Psychologie, Heft 2, comes into my hands with experiments on the measurement of space recorded in it, which, in the author's view, prove the feeling of muscular strain to be a principal factor in our vision of extent. As Münsterberg worked three hours a day for a year and a half at comparing the length of lines, seen with his eyes in different positions; and as he carefully averaged and 'percented' 20,000 observations, his conclusion must be listened to with great respect. Briefly it is this, that "our judgments of size depend on a comparison of the intensity of the feelings of movement which arise in our eyeball-muscles as we glance over the distance, and which fuse with the sensations of light" (p. 142). The facts upon which the conclusion is based are certain constant errors which Münsterberg found according as the standard or given interval was to the right or the left of the interval to be marked off as equal to it, or as it was above or below it, or stood in some more complicated relation still. He admits that he cannot explain all the errors in detail, and that we "stand before results which seem surprising and not to be unravelled, because we cannot analyze the elements which enter into the complex sensation which we receive." But he has no doubt whatever of the general fact "that the movements of the eyes and the sense of their position when fixed exert so decisive an influence on our estimate of the spaces seen, that the errors cannot possibly be explained by anything else than the movement-feelings and their reproductions in the memory" (pp. 166, 167). It is presumptuous to doubt a man's opinion when you haven't had his experience; and yet there are a number of points which make me feel like suspending judgment in regard to Herr M.'s _dictum_. He found, for example, a constant tendency to underestimate intervals lying to the right, and to overestimate intervals lying to the left. He ingeniously explains this as a result of the habit of _reading_, which trains us to move our eyes easily along straight lines from left to right, whereas in looking from right to left we move them in curved lines across the page. As we _measure intervals as straight lines_, it costs more muscular effort to measure from right to left than the other way, and an interval lying to the left seems to us consequently longer than it really is. Now I have been a reader for more years than Herr Münsterberg; and yet with me there is a strongly pronounced error the other way. It is the rightward-lying interval which to me seems longer than it really is. Moreover, Herr M. wears concave spectacles, and looked through them with his _head fixed_. May it not be that some of the errors were due to distortion of the retinal image, as the eye looked no longer through the centre but through the margin of the glass? In short, with all the presumptions which we have seen against muscular contraction being definitely felt as length, I think that there may be explanations of Herr M.'s results which have escaped even his sagacity; and I call for a suspension of judgment until they shall have been confirmed by other observers. I do not myself doubt that our feeling of seen extent may be _altered_ by concomitant muscular feelings. In Chapter XVII (pp. 28-30) we saw many examples of similar alterations, interferences with, or exaltations of, the sensory effect of one nerve-process by another. I do not see why currents from the muscles or eyelids, coming in at the same time with a retinal impression, might not make the latter seem bigger, in the same way that a greater _intensity_ in the retinal stimulation makes it seem bigger; or in the way that a greater extent of surface excited makes the color of the surface seem stronger, or if it be a skin-surface, makes its heat seem greater; or in the way that the coldness of the dollar on the forehead (in Weber's old experiments) made the dollar seem heavier. But this is a _physiological_ way; and the bigness gained is that of the retinal image after all. If I understand Münsterberg's meaning, it is quite different from this: the bigness belongs to the muscular feelings, as such, and is merely _associated_ with those of the retina. _This_ is what I deny.

[202] Archiv f. (Anat. u.) Physiol. (1889), p. 543.

[203] _Ibid._ p. 496.

[204] _Ibid._ p. 497. Goldscheider thinks that our muscles do not even give us the feeling of _resistance_, that being also due to the articular surfaces; whilst _weight_ is due to the tendons. _Ibid._ p. 541.

[205] "Whilst the memories which we seeing folks preserve of a man all centre round a certain exterior form composed of his image, his height, his gait, in the blind all these memories are referred to something quite different, namely, _the sound of his voice_." (Dunan, Rev. Phil., xxv. 357.)

[206] Vol. xxv. pp. 357-8.

[207] P. 135.

[208] Essay conc. Hum. Und., bk. ii. chap. ix. § 8.

[209] Philosophical Transactions, 1841. In T. K. Abbot's Sight and Touch there is a good discussion of these cases. Obviously, positive cases are of more importance than negative. An under-witted peasant, Noé M., whose case is described by Dr. Dufour of Lausanne (Guerison d'un Aveugle né; 1876) is much made of by MM. Naville and Dunan; but it seems to me only to show how little _some_ people can deal with new experiences in which others find themselves quickly at home. This man could not even tell whether one of his first objects of sight moved or stood still (p. 9).

[210] What may be the physiological process connected with this increased sensation of depth is hard to discover. It seems to have nothing to do with the parts of the retina affected, since the mere inversion of the picture (by mirrors, reflecting prisms, etc.), without inverting the head, does not seem to bring it about; nothing with sympathetic axial rotation of the eyes, which might enhance the perspective through exaggerated disparity of the two retinal images (see J. J. Müller, 'Raddrehung u. Tiefendimension,' Leipzig Acad. Berichte, 1875, page 124), for one-eyed persons get it as strongly as those with two eyes. I cannot find it to be connected with any alteration in the pupil or with any ascertainable strain in the muscles of the eye, sympathizing with those of the body. The exaggeration of distance is even greater when we throw the head over backwards and contract our superior recti in getting the view, than when we bend forward and contract the inferior recti. Making the eyes diverge slightly by weak prismatic glasses has no such effect. To me, and to all whom I have asked to repeat the observation, the result is so marked that I do not well understand how such an observer as Helmholtz, who has carefully examined vision with inverted head, can have overlooked it. (See his Phys. Optik, pp. 488, 723, 728, 772.) I cannot help thinking that anyone who can explain the exaggeration of the depth-sensation in this case will at the same time throw much light on its normal constitution.

[211] "In Froriep's Notizen (1838, July), No. 133, is to be found a detailed account, with a picture, of an Esthonian girl, Eva Lauk, then fourteen years old, born with neither arms nor legs, which concludes with the following words: 'According to the mother, her intellect developed quite as fast as that of her brother and sisters; in particular, she came as quickly to a right judgment of the size and distance of visible objects, although, of course, she had no use of hands.'" (Schopenhauer, Welt als Wille, ii. 44.)

[212] Physiol. Optik, p. 438. Helmholtz's reservation of 'qualities' is inconsistent. Our judgments of light and color vary as much as our judgments of size, shape, and place, and ought by parity of reasoning to be called intellectual products and not sensations. In other places he does treat color as if it were an intellectual product.

[213] It is needless at this point to consider what Helmholtz's views of the nature of the intellectual space-yielding process may be. He vacillates--we shall later see how.

[214] _Op. cit._ p. 214.

[215] Before embarking on this new topic it will be well to shelve, once for all, the problem of what is the physiological process that underlies the distance-feeling. Since one-eyed people have it, and are inferior to the two-eyed only in measuring its gradations, it can have no exclusive connection with the double and disparate images produced by binocular parallax. Since people with closed eyes, looking at an after-image, do not usually see it draw near or recede with varying convergence, it cannot be simply constituted by the convergence-feeling. For the same reason it would appear non-identical with the feeling of accommodation. The differences of apparent parallactic movement between far and near objects as we move our head cannot constitute the distance-sensation, for such differences may be easily reproduced experimentally (in the movements of visible spots against a background) without engendering any illusion of perspective. Finally, it is obvious that visible faintness, dimness, and smallness _are_ not _per se_ the feeling of visible distance, however much in the case of well-known objects they _may_ serve as signs to suggest it.

A certain maximum distance-value, however, being given to the field of view of the moment, whatever it be, the feelings that accompany the processes just enumerated become so many _local signs_ of the gradation of distances within this maximum depth. They help us to subdivide and measure it. Itself, however, is felt as a unit, a total distance-value, determining the vastness of the whole field of view, which accordingly appears as an abyss of a certain volume. And the question still persists, what neural process is it that underlies the sense of this distance-value?

Hering, who has tried to explain the gradations within it by the interaction of certain native distance-values belonging to each point of the two retinæ, seems willing to admit that the _absolute_ scale of the space-volume within which the natively fixed relative distances shall appear is _not_ fixed, but determined each time by 'experience in the widest sense of the word' (_Beiträge_, p. 344). What he calls the _Kernpunkt_ of this space-volume is the point we are momentarily fixating. The absolute scale of the whole volume depends on the absolute distance at which this _Kernpunkt_ is judged to lie from the person of the looker. "By an alteration of the localization of the _Kernpunkt_, the _inner_ relations of the seen space are nowise altered; this space in its totality is as a fixed unit, so to speak, displaced with respect to the self of the looker" (p. 345). But what constitutes the localization of the _Kernpunkt_ itself at any given time, except 'Experience,' i.e., higher cerebral and intellectual processes, involving memory, Hering does not seek to define.

Stumpf, the other sensationalist writer who has best realized the difficulties of the problem, thinks that the primitive sensation of distance must have an immediate physical antecedent, either in the shape of "an organic alteration accompanying the process of accommodation, or else given directly in the specific energy of the optic nerve." In contrast with Hering, however, he thinks that it is the _absolute_ distance of the spot fixated which is thus primitively, immediately, and physiologically given, and not the relative distances of other things about this spot. These, he thinks, are originally seen in what, broadly speaking, may be termed one plane with it. Whether the distance of this plane, considered as a phenomenon of our primitive sensibility, be an invariable datum, or susceptible of fluctuation, he does not, if I understand him rightly, undertake dogmatically to decide, but inclines to the former view. For him then, as for Hering, higher cerebral processes of association, under the name of 'Experience,' are the authors of fully one-half part of the distance-perceptions which we at any given time may have.

Hering's and Stumpf's theories are reported for the English reader by Mr. Sully (in Mind, iii. pp. 172-6). Mr. Abbott, in his Sight and Touch (pp. 96-8), gives a theory which is to me so obscure that I only refer the reader to its place, adding that it seems to make of distance a fixed function of retinal sensation as modified by focal adjustment. Besides these three authors I am ignorant of any, except Panum, who may have attempted to define distance as in any degree an immediate sensation. And with them the direct sensational share is reduced to a very small proportional part, in our completed distance-judgments.

Professor Lipps, in his singularly acute Psychologische Studien (p. 69 ff.), argues, as Ferrier, in his review of Berkeley (Philosophical Remains, ii. 330 ff.), had argued before him, that it is _logically impossible_ we should perceive the distance of anything from the eye by sight; for a _seen_ distance can only be between _seen_ termini; and one of the termini, in the case of distance from the eye, is the eye itself, which is not seen. Similarly of the distance of two points behind each other: the near one _hides_ the far one, no space is seen between them. For the space between two objects to be _seen_, both must appear _beside_ each other, then the space in question will be _visible_. On no other condition is its visibility possible. The conclusion is that things can properly be seen only in what Lipps calls a surface, and that our knowledge of the third dimension must needs be conceptual, not sensational or visually intuitive.

But no arguments in the world can prove a feeling which actually exists to be impossible. The feeling of depth or distance, of farness or awayness, does actually exist as a fact of our visual sensibility. All that Professor Lipps's reasonings prove concerning it is that it is not linear in its character, or in its immediacy fully homogeneous and consubstantial with the feeling of literal distance between two seen termini; in short, that there are _two_ sorts of optical sensation, each inexplicably due to a peculiar neural process. The neural process is easily discovered, in the case of lateral extension or spreadoutness, to be the number of retinal nerve-ends affected by the light; in the case of protension or mere farness it is more complicated and, as we have concluded, is still to seek. The two sensible qualities unite in the primitive visual bigness. The measurement of their various amounts against each other obeys the general laws of all such measurements. We discover their equivalencies by means of objects, apply the same units to both, and translate them into each other so habitually that at last they get to seem to us even quite similar in kind. This final appearance of homogeneity may perhaps be facilitated by the fact that in binocular vision two points situated on the prolongation of the optical axis of _one_ of the eyes, so that the near one hides the far one, are by the _other_ eye seen laterally apart. Each eye has in fact a foreshortened lateral view of the other's line of sight. In The London Times for Feb. 8, 1884, is an interesting letter by J. D. Dougal, who tries to explain by this reason why two-eyed rifle-shooting has such advantages over shooting with one eye closed.

[216] Just so, a pair of spectacles held an inch or so from the eyes seem like one large median glass. The faculty of seeing stereoscopic slides single without an instrument is of the utmost utility to the student of physiological optics, and persons with strong eyes can easily acquire it. The only difficulty lies in dissociating the degree of accommodation from the degree of convergence which it usually accompanies. If the right picture is focussed by the right eye, the left by the left eye, the optic axes must either be parallel or converge upon an imaginary point some distance behind the plane of the pictures, according to the size and distance apart of the pictures. The accommodation, however, has to be made for the plane of the pictures itself, and a near accommodation with a far-off convergence is something which the ordinary use of our eyes never teaches us to effect.

[217] These two observations prove the law of identical direction only for objects which excite the foveæ or lie in the line of direct looking. Observers skilled in indirect vision can, however, more or less easily verify the law for outlying retinal points.

[218] This essay, published in the Philosophical Transactions, contains the germ of almost all the methods applied since to the study of optical perception. It seems a pity that England, leading off so brilliantly the modern epoch of this study, should so quickly have dropped out of the field. Almost all subsequent progress has been made in Germany, Holland, and, _longo intervallo_, America.

[219] This is no place to report this controversy, but a few bibliographic references may not be inappropriate. Wheatstone's own experiment is in section 12 of his memoir. In favor of his interpretation see Helmholtz, Phys. Opt., pp. 737-9; Wundt, Physiol. Psychol., 2te Aufl. p. 144; Nagel, Sehen mit zwei Augen, pp. 78-82. Against Wheatstone see Volkmann, Arch. f. Ophth., v. 2-74, and Untersuchungen, p. 266; Hering, Beiträge zur Physiologie, 29-45, also in Hermann's Hdbch. d. Physiol., Bd. iii. 1 Th. p. 435; Aubert, Physiologie d. Netzhaut, p. 322; Schön, Archiv f. Ophthal., xxiv. 1. pp. 56-65; and Donders, _ibid._ xiii. 1. p. 15 and note.

[220] When we see the finger the whole time, we usually put it in the line joining object and left eye if it be the left finger, joining object and right eye if it be the right finger. Microscopists, marksmen, or persons one of whose eyes is much better than the other, almost always refer directions to a single eye, as may be seen by the position of the shadow on their face when they point at a candle-flame.

[221] Professor Joseph Le Conte, who believes strongly in the identity-theory, has embodied the latter in a pair of laws of the relation between positions seen single and double, near or far, on the one hand, and convergences and retinal impressions, on the other, which, though complicated, seems to me by far the best descriptive formulation yet made of the normal facts of vision. His account is easily accessible to the reader in his volume 'Sight' in the International Scientific Series, bk. ii. c. 8, so I say no more about it now, except that it does not solve any of the difficulties we are noting in the identity-theory, nor account for the other fluctuating perceptions of which we go on to treat.

[222] Naturally it takes a smaller object at a less distance to cover by its image a constant amount of retinal surface.

[223] Archiv f. Ophthal., Bd. xvii. Abth. 2, pp. 44-6 (1871).

[224] A. W. Volkmann, Untersuchungen, p. 253.

[225] Philosophical Transactions, 1852, p. 4.

[226] Physiol. Optik, 649-664. Later this author is led to value convergence more highly. Arch. f. (Anat. u.) Physiol. (1878), p. 322.

[227] Anomalies of Accommodation and Refraction (New Sydenham Soc. Transl., London, 1864), p. 155.

[228] These strange contradictions have been called by Aubert 'secondary' deceptions of judgment. See Grundzüge d. Physiologischen Optik (Leipzig, 1876), pp. 601, 615, 627. One of the best examples of them is the small size of the moon as first seen through a telescope. It is larger and brighter, so we see its details more distinctly and judge it nearer. But because we judge it so much nearer we think it must have grown smaller. Cf. Charpentier in Jahresbericht, x. 430.

[229] Revue Philosophique, iii. 9, p. 220.

[230] See Chapter XXIV.

[231] The only exception seems to be when we expressly wish to abstract from particulars, and to judge of the general 'effect.' Witness ladies trying on new dresses with their heads inclined and their eyes askance; or painters in the same attitude judging of the 'values' in their pictures.

[232] The importance of Superposition will appear later on.

[233] Physiol. Optik, p. 817.

[234] Bowditch and Hall, in Journal of Physiology, vol. iii. p. 299. Helmholtz tries to explain this phenomenon by unconscious rotations of the eyeball. But movements of the eyeball can only explain such appearances of movements as are the same over the whole field. In the windowed board one part of the field seems to move in one way, another part in another. The same is true when we turn from the spiral to look at the wall--the _centre_ of the field alone swells out or contracts, the margin does the reverse or remains at rest. Mach and Dvorak have beautifully proved the impossibility of eye-rotations in this case (Sitzungsber. d. Wiener Akad., Bd. lxi.). See also Bowditch and Hall's paper as above, p. 300.

[235] Bulletins de l'Acad. de Belgique, xxi. 2; Revue Philosophique, vi. pp. 223-5; Physiologische Psychologie, 2te Aufl. p. 103. Compare Münsterberg's views, Beiträge, Heft 2, p. 174.

[236] Physiol. Optik, pp. 562-71.

[237] Physiol. Psych., pp. 107-8.

[238] Grundtatsachen des Seelenlebens, pp. 526-30.

[239] Cf. _supra_, vol. I. p. 515 ff.

[240] See Archiv f. Ophthalm., v. 2, 1 (1859), where many more examples are given.

[241] Untersuchungen, p. 250; see also p. 242.

[242] I pass over certain difficulties about double images, drawn from the perceptions of a few squinters (e.g. by Schweigger, Klin. Untersuch über das Schielen, Berlin, 1881; by Javal, Annales d'Oculistique, lxxxv. p. 217), because the facts are exceptional at best and very difficult of interpretation. In favor of the sensationalistic or nativistic view of one such case, see the important paper by Von Kries, Archiv f. Ophthalm., xxiv. 4, p. 117.

[243] Physiologische Untersuchungen im Gebiete der Optik, v.

[244] Cf. E. Mach, Beiträge zur Analyse der Empfindungen, p. 87.

[245] Cf. V. Egger, Revue Philos., xx. 488.

[246] Loeb (Pflüger's Archiv, xl. 274) has proved that muscular changes of adaptation in the eye for near and far distance are what determine the form of the relief.

[247] The strongest passage in Helmholtz's argument against sensations of space is relative to these fluctuations of seen relief: "Ought one not to conclude that if sensations of relief exist at all, they must be so faint and vague as to have no influence compared with that of past experience? Ought we not to believe that the perception of the third dimension may have arisen _without_ them, since we now see it taking place as well _against_ them as _with_ them?" (Physiol. Optik, p. 817.)

[248] Cf. E. Mach, Beiträge, etc., p. 90, and the preceding chapter of the present work, p. 86 ff.

[249] I ought to say that I seem always able to see the cross rectangular at will. But this appears to come from an imperfect absorption of the rectangular after-image by the inclined plane at which the eyes look. The cross, with me, is apt to detach itself from this and then look square. I get the illusion better from the circle, whose after-image becomes in various ways elliptical on being projected upon the different surfaces of the room, and cannot then be easily made to look circular again.

[250] In Chapter XVIII, p. 74, I gave a reason why imaginations _ought_ not to be as vivid as sensations. It should be borne in mind that that reason does not apply to these complemental imaginings of the real shape of things actually before our eyes.

[251] Hermann's Handb. der Physiologie, iii. 1. p. 565-71.

[252] Bulletin de l'Académie de Belgique, 2me Série, xix. 2.

[253] Wundt seeks to explain all these illusions by the relatively stronger 'feeling of innervation' needed to move the eyeballs upwards,--a careful study of the muscles concerned is taken to prove this,--and a consequently greater estimate of the distance traversed. It suffices to remark, however, with Lipps, that were the innervation all, a column of S's placed on top of each other should look each larger than the one below it, and a weathercock on a steeple gigantic, neither of which is the case. Only the halves of _the same object_ look different in size, because the customary correction for foreshortening bears only on the relations of the parts of special _things_ spread out before us. Cf. Wundt, Physiol. Psych., 2te Aufl. ii. 96-8; Th. Lipps, Grundtatsachen, etc., p. 535.

[254] Hering would partly solve in this way the mystery of Figs. 60, 61, and 67. No doubt the explanation partly applies; but the strange cessation of the illusion when we fix the gaze fails to be accounted for thereby.

[255] Helmholtz has sought (Physiol. Optik, p. 715) to explain the divergence of the apparent vertical meridians of the two retinæ, by the manner in which an identical line drawn on the ground before us in the median plane will throw its images on the two eyes respectively. The matter is too technical for description here; the unlearned reader may be referred for it to J. Le Conte's Sight in the Internat. Scient. Series, p. 198 ff. But, for the benefit of those to whom _verbum sat_, I cannot help saying that it seems to me that the _exactness_ of the relation of the two meridians--whether divergent or not, for their divergence differs in individuals and often in one individual at diverse times--precludes its being due to the mere habitual falling-off of the image of one objective line on both. Le Conte, e.g., measures their position down to a sixth of a degree, others to tenths. This indicates an organic identity in the sensations of the two retinæ, which the experience of median perspective horizontals may roughly have agreed with, but hardly can have engendered. Wundt explains the divergence as usual, by the _Innervationsgefühl_ (_op. cit._. ii. 99 ff.).

[256] Physiol. Optik, p. 547.

[257] "We can with a short ruler draw a line as long as we please on a plane surface by first drawing one as long as the ruler permits, and then sliding the ruler somewhat along the drawn line and drawing again, etc. If the ruler is exactly straight, we get in this way a straight line. If it is somewhat curved we get a circle. Now, instead of the sliding ruler we use in the field of sight the central spot of distinctest vision impressed with a linear sensation of sight, which at times may be intensified till it becomes an after-image. We follow, in looking, the direction of this line, and in so doing we slide the line along itself and get a prolongation of its length. On a plane surface we can carry on this procedure on any sort of a straight or curved ruler, but in the field of vision there is for each direction and movement of the eye only one sort of line which it is possible for us to slide along in its own direction continually." These are what Helmholtz calls the 'circles of direction' of the visual field--lines which he has studied with his usual care. Cf. Physiol. Optik, p. 548 ff.

[258] Cf. Hering in Hermann's Handb. der Physiol., iii. 1, pp. 558-4.

[259] This shrinkage and expansion of the absolute space-value of the total optical sensation remains to my mind the most obscure part of the whole subject. It is a real optical sensation, seeming introspectively to have nothing to do with locomotor or other suggestions. It is easy to say that 'the Intellect produces it,' but what does that mean? The investigator who will throw light on this one point will probably clear up other difficulties as well.

[260] Examination of Hamilton, 3d ed. p. 283.

[261] Senses and Intellect, 3d ed. p. 183.

[262] Exam. of Hamilton, 3d ed. p. 283.

[263] Senses and Intellect, p. 372.

[264] Vierfache Wurzel des Satzes vom zureichenden Grunde, pp. 52-7.

[265] Psychol. als Wissenschaft, § 111.

[266] Psychol. als Wissenschaft, § 113.

[267] Lehrbuch d. Psychol., 2te Auflage, Bd. ii. p. 66. Volkmann's fifth chapter contains a really precious collection of historical notices concerning space-perception theories.

[268] Why talk of 'genetic theories'? when we have in the next breath to write as Wundt does: "If then we must regard the intuition of space as a product that simply emerges from the conditions of our mental and physical organization, nothing need stand in the way of our designating it as one of the _a priori_ functions with which consciousness is endowed." (Logik, ii. 460.)

[269] P. 430.

[270] Pp. 430, 449.

[271] P. 428.

[272] P. 442.

[273] Pp. 442, 818.

[274] P. 798. Cf. also Popular Scientific Lectures, pp. 301-3.

[275] P. 456; see also 428, 441.

[276] P. 797.

[277] P. 812.

[278] Bottom of page 797.

[279] In fact, to borrow a simile from Prof. G. E. Müller (Theorie der sinnl. Aufmerksamkeit, p. 38), the various senses bear in the Helmholtzian philosophy of perception the same relation to the 'object' perceived by their means that a troop of jolly drinkers bear to the landlord's bill, when no one has any money, but each hopes that one of the rest will pay.

[280] Grundtatsachen des Seelenlebens (1883), pp. 480, 591-2. Psychologische Studien (1885), p. 14.

[281] Psychology, ii. p. 174.

[282] _Ibid._ p. 168.

[283] Senses and Intellect, 3d ed. pp. 366-75.

[284] Cf. Hall and Donaldson in Mind, x. 559.

[285] As other examples of the confusion, take Mr. Sully: "The _fallacious assumption_ that there can be an idea of distance in general, apart from particular distances" (Mind, iii. p. 177); and Wundt: "An indefinite localization, which waits for experience to give it its reference to real space, stands in contradiction with the very idea of localization, which means the reference to a determinate point of space" (Physiol. Psych., 1te Aufl. p. 480).

[286] G. Berkeley: Essay towards a new Theory of Vision; Samuel Bailey: A Review of Berkeley's Theory of Vision (1842); J. S. Mill's Review of Bailey, in his Dissertations and Disquisitions, vol. ii; Jas. Ferrier: Review of Bailey, in 'Philosophical Remains,' vol. ii; A. Bain: Senses and Intellect, 'Intellect,' chap. i; H. Spencer: Principles of Psychology, pt. vi. chaps. xiv, xvi; J. S. Mill: Examination of Hamilton, chap. xiii (the best statement of the so-called English empiricist position); T. K. Abbott: Sight and Touch, 1861 (the first English book to go at all minutely into _facts_; Mr. Abbott maintaining retinal sensations to be originally of space in three dimensions); A. C. Fraser: Review of Abbott, in North British Review for Aug. 1864; another review in Macmillan's Magazine, Aug. 1866; J. Sully: Outlines of Psychology, chap. vi; J. Ward: Encyclop. Britannica, 9th Ed., article 'Psychology,' pp. 53-5; J. E. Walter: The Perception of Space and Matter (1879)--I may also refer to a discussion between Prof. G. Groom Robertson, Mr. J. Ward, and the present writer, in Mind, vol. xiii.--The present chapter is only the filling out with detail of an article entitled 'The Spatial Quale,' which appeared in the Journal of Speculative Philosophy for January 1879 (xiii. 64).



CHAPTER XXI.[287]

THE PERCEPTION OF REALITY.

BELIEF.


Everyone knows the difference between imagining a thing and believing in its existence, between supposing a proposition and acquiescing in its truth. In the case of acquiescence or belief, the object is not only apprehended by the mind, but is held to have reality. Belief is thus the mental state or function of cognizing reality. As used in the following pages, 'Belief' will mean every degree of assurance, including the highest possible certainty and conviction.

There are, as we know, two ways of studying every psychic state. First, the way of analysis: What does it consist in? What is its inner nature? Of what sort of mind-stuff is it composed? Second, the way of history: What are its conditions of production, and its connection with other facts?

Into the first way we cannot go very far. _In its inner nature, belief, or the sense of reality, is a sort of feeling more allied to the emotions than to anything else._ Mr. Bagehot distinctly calls it the 'emotion' of conviction. I just now spoke of it as acquiescence. It resembles more than anything what in the psychology of volition we know as consent. Consent is recognized by all to be a manifestation of our active nature. It would naturally be described by such terms as 'willingness' or the 'turning of our disposition.' What characterizes both consent and belief is the cessation of theoretic agitation, through the advent of an idea which is inwardly stable, and fills the mind solidly to the exclusion of contradictory ideas. When this is the case, motor effects are apt to follow. Hence the states of consent and belief, characterized by repose on the purely intellectual side, are both intimately connected with subsequent practical activity. This inward stability of the mind's content is as characteristic of disbelief as of belief. But we shall presently see that we never disbelieve anything except for the reason that we believe something else which contradicts the first thing.[288] Disbelief is thus an incidental complication to belief, and need not be considered by itself.

      *       *       *       *       *

_The true opposites of belief,_ psychologically considered, _are doubt and inquiry, not disbelief._ In both these states the content of our mind is in unrest, and the emotion engendered thereby is, like the emotion of belief itself, perfectly distinct, but perfectly indescribable in words. Both sorts of emotion may be pathologically exalted. One of the charms of drunkenness unquestionably lies in the deepening of the sense of reality and truth which is gained therein. In whatever light things may then appear to us, they seem more utterly what they are, more 'utterly utter' than when we are sober. This goes to a fully unutterable extreme in the nitrous oxide intoxication, in which a man's very soul will sweat with conviction, and he be all the while unable to tell what he is convinced of at all.[289] The pathological state opposed to this solidity and deepening has been called the questioning mania (_Grübelsucht_ by the Germans). It is sometimes found as a substantive affection, paroxysmal or chronic, and consists in the inability to rest in any conception, and the need of having it confirmed and explained. 'Why do I stand here where I stand?' 'Why is a glass a glass, a chair a chair?' 'How is it that men are only of the size they are? Why not as big as houses,' etc., etc.[290] There is, it is true, another pathological state which is as far removed from doubt as from belief, and which some may prefer to consider the proper contrary of the latter state of mind. I refer to the feeling that everything is hollow, unreal, dead. I shall speak of this state again upon a later page. The point I wish to notice here is simply that belief and disbelief are but two aspects of one psychic state.

      *       *       *       *       *

John Mill, reviewing various opinions about belief, comes to the conclusion that no account of it can be given:

"What," he says, "is the difference _to our minds_ between thinking
of a reality and representing to ourselves an imaginary picture? I
confess I can see no escape from the opinion that the distinction is
ultimate and primordial. There is no more difficulty in holding it
to be so than in holding the difference between a sensation and an
idea to be primordial. It seems almost another aspect of the same
difference.... I cannot help thinking, therefore, that there is in the
remembrance of a real fact, as distinguished from that of a thought,
an element which does not consist... in a difference between the mere
ideas which are present to the mind in the two cases. This element,
howsoever we define it, constitutes belief, and is the difference
between Memory and Imagination. From whatever direction we approach,
this difference seems to close our path. When we arrive at it, we seem
to have reached, as it were, the central point of our intellectual
nature, presupposed and built upon in every attempt we make to explain
the more recondite phenomena of our mental being."[291]

If the words of Mill be taken to apply to the mere subjective analysis of belief--to the question, What does it feel like when we have it?--they must be held, on the whole, to be correct. Belief, the sense of reality, feels like itself--that is about as much as we can say.

Prof. Brentano, in an admirable chapter of his _Psychologie_, expresses this by saying that conception and belief (which he names _judgment_) are two different fundamental psychic phenomena. What I myself have called (Vol. I, p. 275) the 'object' of thought may be comparatively simple, like "Ha! what a pain," or "It-thunders"; or it may be complex, like "Columbus-discovered-America-in-1492," or "There-exists-an-all-wise-Creator-of-the-world." In either case, however, the mere thought of the object may exist as something quite distinct from the belief in its reality. The belief, as Brentano says, presupposes the mere thought:

"Every object comes into consciousness in a twofold way, as simply
thought of [_vorgestellt_] and as admitted [_anerkannt_] or
denied. The relation is analogous to that which is assumed by most
philosophers (by Kant no less than by Aristotle) to obtain between
mere thought and desire. Nothing is ever desired without being thought
of; but the desiring is nevertheless a second quite new and peculiar
form of relation to the object, a second quite new way of receiving
it into consciousness. No more is anything judged [i.e., believed or
disbelieved] which is not thought of too. But we must insist that, so
soon as the object of a thought becomes the object of an assenting
or rejecting judgment, our consciousness steps into an entirely new
relation towards it. It is then twice present in consciousness, as
thought of, and as held for real or denied; just as when desire
awakens for it, it is both thought and simultaneously desired." (P.
266.)

The commonplace doctrine of 'judgment' is that it consists in the combination of 'ideas' by a 'copula' into a 'proposition,' which may be of various sorts, as affirmative, negative, hypothetical, etc. But who does not see that in a disbelieved or doubted or interrogative or conditional proposition, the ideas are combined in the same identical way in which they are in a proposition which is solidly believed? _The way in which the ideas are combined is a part of the inner constitution of the thought's object or content._ That object is sometimes an articulated whole with relations between its parts, amongst which relations, that of predicate to subject may be one. But when we have got our object with its inner constitution thus defined in a proposition, then the question comes up regarding the object as a whole: 'Is it a real object? is this proposition a true proposition or not?' And in the answer _Yes_ to _this_ question lies that new psychic act which Brentano calls 'judgment,' but which I prefer to call 'belief.'

In every proposition, then, so far as it is believed, questioned, or disbelieved, four elements are to be distinguished, the subject, the predicate, and their relation (of whatever sort it be)--these form the _object_ of belief--and finally the psychic attitude in which our mind stands towards the proposition taken as a whole--and this is the belief itself.[292]

Admitting, then, that this attitude is a state of consciousness _sui generis_, about which nothing more can be said in the way of internal analysis, let us proceed to the second way of studying the subject of belief: _Under what circumstances do we think things real?_ We shall soon see how much matter this gives us to discuss.


THE VARIOUS ORDERS OF REALITY.


Suppose a new-born mind, entirely blank and waiting for experience to begin. Suppose that it begins in the form of a visual impression (whether faint or vivid is immaterial) of a lighted candle against a dark background, and nothing else, so that whilst this image lasts it constitutes the entire universe known to the mind in question. Suppose, moreover (to simplify the hypothesis), that the candle is only imaginary, and that no 'original' of it is recognized by us psychologists outside. Will this hallucinatory candle be believed in, will it have a real existence for the mind?

What possible sense (for that mind) would a suspicion have that the candle was not real? What would doubt or disbelief of it imply? When _we_, the onlooking psychologists, say the candle is unreal, we mean something quite definite, viz., that there is a world known to _us_ which _is_ real, and to which we perceive that the candle does not belong; it belongs exclusively to that individual mind, has no _status_ anywhere else, etc. It exists, to be sure, in a fashion, for it forms the content of that mind's hallucination; but the hallucination itself, though unquestionably it is a sort of existing fact, has no knowledge of _other_ facts; and since those _other_ facts are the realities par _excellence_ for us, and the only things we believe in, the candle is simply outside of our reality and belief altogether.

By the hypothesis, however, the _mind which sees the candle_ can spin no such considerations as these about it, for of other facts, actual or possible, it has no inkling whatever. That candle is its all, its absolute. Its entire faculty of attention is absorbed by it. It _is_, it is _that_; it is _there_; no other possible candle, or quality of this candle, no other possible place, or possible object in the place, no alternative, in short, suggests itself as even conceivable; so how can the mind help believing the candle real? The supposition that it might possibly not do so is, under the supposed conditions, unintelligible.[293]

This is what Spinoza long ago announced:

"Let us conceive a boy," he said, "imagining to himself a horse,
and taking note of nothing else. As this imagination involves the
existence of the horse, _and the boy has no perception which annuls
its existence,_ he will necessarily contemplate the horse as present,
nor will he be able to doubt of its existence, however little
certain of it he may be. I deny that a man in so far as he imagines
[_percipit_] affirms nothing. For what is it to imagine a winged
horse but to affirm that, the horse [that horse, namely] has wings?
For if the mind had nothing before it but the winged horse it would
contemplate the same as present, would have no cause to doubt of its
existence, nor any power of dissenting from its existence, unless
the imagination of the winged horse were joined to an idea which
contradicted [_tollit_] its existence." (Ethics, ii. 49, Scholium.)

The sense that anything we think of is unreal can only come, then, when that thing is contradicted by some other thing of which we think. _Any object which remains uncontradicted is ipso facto believed and posited as absolute reality._

Now, how comes it that one thing thought of can be contradicted by another? It cannot unless it begins the quarrel by saying something inadmissible about that other. Take the mind with the candle, or the boy with the horse. If either of them say, 'That candle or that horse, even when I don't see it, exists in _the outer world_,' he pushes into 'the outer world' an object which may be incompatible with everything which he otherwise knows of that world. If so, he must take his choice of which to hold by, the present perceptions or the other knowledge of the world. If he holds to the other knowledge, the present perceptions are contradicted, _so far as their relation to that world goes._ Candle and horse, whatever they may be, are not existents in outward space. They are existents, of course; they are mental objects; mental objects have existence as mental objects. But they are situated in their own spaces, the space in which they severally appear, and neither of those spaces is the space in which the realities called 'the outer world' exist.

Take again the horse with wings. If I merely dream of a horse with wings, my horse interferes with nothing else and has not to be contradicted. That horse, its wings, and its place, are all equally real. That horse exists no otherwise than as winged, and is moreover really there, for that place exists no otherwise than as the place of that horse, and claims as yet no connection with the other places of the world. But if with this horse I make an inroad into the _world otherwise known_, and say, for example, 'That is my old mare Maggie, having grown a pair of wings where she stands in her stall,' the whole case is altered; for now the horse and place are identified with a horse and place otherwise known, and _what_ is known of the latter objects is incompatible with what is perceived with the former. 'Maggie in her stall with wings! Never!' The wings are unreal, then, visionary. I have dreamed a lie about Maggie in her stall.

The reader will recognize in these two cases the two sorts of judgment called in the logic-books existential and attributive respectively. The candle exists as an outer reality' is an existential, 'My Maggie has got a pair of wings' is an attributive, proposition;[294] and it follows from what was first said that _all propositions, whether attributive or existential, are believed through the very fact of being conceived, unless they clash with other propositions believed, at the same time, by affirming that their terms are the same with the terms of these other propositions._ A dream-candle has existence, true enough; but not the same existence (existence for itself, namely, or _extra mentem meam_) which the candles of waking perception have. A dream-horse has wings; but then neither horse nor wings are the same with any horses or wings known to memory. That we can at any moment think of the same thing which at any former moment we thought of is the ultimate law of our intellectual constitution. But when we now think of it incompatibly with our other ways of thinking it, then we must choose which way to stand by, for we cannot continue to think in two contradictory ways at once. _The whole distinction of real and unreal, the whole psychology of belief, disbelief, and doubt, is thus grounded on two mental facts--first, that we are liable to think differently of the same; and second, that when we have done so, we can choose which way of thinking to adhere to and which to disregard._

The subjects adhered to become real subjects, the attributes adhered to real attributes, the existence adhered to real existence; whilst the subjects disregarded become imaginary subjects, the attributes disregarded erroneous attributes, and the existence disregarded an existence in no man's land, in the limbo 'where footless fancies dwell.' The real things are, in M. Taine's terminology, the _reductives_ of the things judged unreal.


THE MANY WORLDS.


Habitually and practically we do not _count_ these disregarded things as existents at all. For them _Væ victis_ is the law in the popular philosophy; they are not even treated as appearances; they are treated as if they were mere waste, equivalent to nothing at all. To the genuinely philosophic mind, however, they still have existence, though not the same existence, as the real things. _As_ objects of fancy, _as_ errors, _as_ occupants of dreamland, etc., they are in their way as indefeasible parts of life, as undeniable features of the Universe, as the realities are in their way. The total world of which the philosophers must take account is thus composed of the realities _plus_ the fancies and illusions.

Two sub-universes, at least, connected by relations which philosophy tries to ascertain! Really there are more than two sub-universes of which we take account, some of us of this one, and others of that. For there are various categories both of illusion and of reality, and alongside of the world of absolute error (i.e., error confined to single individuals) but still within the world of absolute reality (i.e., reality believed by the complete philosopher) there is the world of collective error, there are the worlds of abstract reality, of relative or practical reality, of ideal relations, and there is the supernatural world. The popular mind conceives of all these sub-worlds more or less disconnectedly; and when dealing with one of them, forgets for the time being its relations to the rest. The complete philosopher is he who seeks not only to assign to every given object of his thought its right place in one or other of these sub-worlds, but he also seeks to determine the relation of each sub-world to the others in the total world which _is_.

The most important sub-universes commonly discriminated from each other and recognized by most of us as existing, each with its own special and separate style of existence, are the following:

(1) The world of sense, or of physical 'things' as we instinctively apprehend them, with such qualities as heat, color, and sound, and such 'forces' as life, chemical affinity, gravity, electricity, all existing as such within or on the surface of the things.

(2) The world of science, or of physical things as the learned conceive them, with secondary qualities and 'forces' (in the popular sense) excluded, and nothing real but solids and fluids and their 'laws' (i.e., customs) of motion.[295]

(3) The world of ideal relations, or abstract truths believed or believable by all, and expressed in logical, mathematical, metaphysical, ethical, or æsthetic propositions.

(4) The world of 'idols of the tribe,' illusions or prejudices common to the race. All educated people recognize these as forming one sub-universe. The motion of the sky round the earth, for example, belongs to this world. That motion is not a recognized item of any of the other worlds; but as an 'idol of the tribe' it really exists. For certain philosophers 'matter' exists only as an idol of the tribe. For science, the 'secondary qualities' of matter are but 'idols of the tribe.'

(5) The various supernatural worlds, the Christian heaven and hell, the world of the Hindoo mythology, the world of Swedenborg's _visa et audita_, etc. Each of these is a consistent system, with definite relations among its own parts. Neptune's trident, e.g., has no status of reality whatever in the Christian heaven; but within the classic Olympus certain definite things are true of it, whether one believe in the reality of the classic mythology as a whole or not. The various worlds of deliberate fable may be ranked with these worlds of faith--the world of the _Iliad_, that of _King Lear_, of the _Pickwick Papers_, etc.[296]

(6) The various worlds of individual opinion, as numerous as men are.

(7) The worlds of sheer madness and vagary, also indefinitely numerous.

_Every object we think of gets at last referred to one world or another of this or of some similar list._ It settles into our belief as a common-sense object, a scientific object, an abstract object, a mythological object, an object of some one's mistaken conception, or a madman's object; and it reaches this state sometimes immediately, but often only after being hustled and bandied about amongst other objects until it finds some which will tolerate its presence and stand in relations to it which nothing contradicts. The molecules and ether-waves of the scientific world, for example, simply kick the object's warmth and color out, they refuse to have any relations with them. But the world of 'idols of the tribe' stands ready to take them in. Just so the world of classic myth takes up the winged horse; the world of individual hallucination, the vision of the candle; the world of abstract truth, the proposition that justice is kingly, though no actual king be just. The various worlds themselves, however, appear (as aforesaid) to most men's minds in no very definitely conceived relation to each other, and our attention, when it turns to one, is apt to drop the others for the time being out of its account. Propositions concerning the different worlds are made from 'different points of view'; and in this more or less chaotic state the consciousness of most thinkers remains to the end. Each world _whilst it is attended to_ is real after its own fashion; only the reality lapses with the attention.


THE WORLD OF 'PRACTICAL REALITIES.'


Each thinker, however, has dominant habits of attention; and these _practically elect from among the various worlds some one to be for him the world of ultimate realities_. From this world's objects he does not appeal. Whatever positively contradicts them must get into another world or die. The horse, e.g., may have wings to its heart's content, so long as it does not pretend to be the real world's horse--_that_ horse is absolutely wingless. For most men, as we shall immediately see, the 'things of sense' hold this prerogative position, and are the absolutely real world's nucleus. Other things, to be sure, may be real for this man or for that--things of science, abstract moral relations, things of the Christian theology, or what not. But even for the special man, these things are usually real with a less real reality than that of the things of sense. They are taken less seriously; and the very utmost that can be said for anyone's belief in them is that it is as strong as his 'belief in his own senses.'[297]

In all this the everlasting partiality of our nature shows itself, our inveterate propensity to choice. For, in the strict and ultimate sense of the word existence, everything which can be thought of at all exists as _some_ sort of object, whether mythical object, individual thinker's object, or object in outer space and for intelligence at large. Errors, fictions, tribal beliefs, are parts of the whole great Universe which God has made, and He must have meant all these things to be in it, each in its respective place. But for us finite creatures, "'tis to consider too curiously to consider so." The mere fact of appearing as an object at all is not enough to constitute reality. That may be metaphysical reality, reality for God; but what we need is practical reality, reality for ourselves; and, to have that, an object must not only appear, but it must appear both _interesting_ and _important_. The worlds whose objects are neither interesting nor important we treat simply negatively, we brand them as _un_real.

_In the relative sense,_ then, the sense in which we contrast reality with simple _un_reality, and in which one thing is said to have _more_ reality than another, and to be more believed, _reality means simply relation to our emotional and active life._ This is the only sense which the word ever has in the mouths of practical men. _In this sense, whatever excites and stimulates our interest is real;_ whenever an object so appeals to us that we turn to it, accept it, fill our mind with it, or practically take account of it, so far it is real for us, and we believe it. Whenever, on the contrary, we ignore it, fail to consider it or act upon it, despise it, reject it, forget it, so far it is unreal for us and disbelieved. Hume's account of the matter was then essentially correct, when he said that belief in anything was simply the having the idea of it in a lively and active manner:

"I say, then, that belief is nothing but a more vivid, lively,
forcible, firm, steady conception of an object than the imagination
alone is ever able to attain.... It consists not in the peculiar
nature or order of the ideas, but in the _manner_ of their conception
and in their _feeling_ to the mind. I confess that it is impossible
perfectly to explain this feeling or manner of conception.... Its
true and proper name... is _belief_, which is a term that everyone
sufficiently understands in common life. And in philosophy we can go
no farther than assert that belief is something felt by the mind,
which distinguishes the idea of the judgment from the fictions of the
imagination.[298] It gives them more weight and influence; makes them
appear of greater importance; enforces them in the mind; gives them
a superior influence on the passions, and renders them the governing
principle in our actions."[299]

Or as Prof. Bain puts it: "In its essential character, belief is a phase of our active nature--otherwise called the Will."[300]

      *       *       *       *       *

The object of belief, then, reality or real existence, is something quite different from all the other predicates which a subject may possess. Those are properties intellectually or sensibly intuited. When we add any one of them to the subject, we increase the intrinsic content of the latter, we enrich its picture in our mind. But adding reality does not enrich the picture in any such inward way; it leaves it inwardly as it finds it, and only fixes it and stamps it in to _us_.

"The real," as Kant says, "contains no more than the possible. A
hundred real dollars do not contain a penny more than a hundred
possible dollars.... By whatever, and by however many, predicates I
may think a thing, nothing is added to it if I add that the thing
exists.... Whatever, therefore, our concept of an object may contain,
we must always step outside of it in order to attribute to it
existence."[301]

The 'stepping outside' of it is the establishment either of immediate practical relations between it and ourselves, or of relations between it and other objects with which we have immediate practical relations. Relations of this sort, which are as yet not transcended or superseded by others, are _ipso facto_ real relations, and confer reality upon their objective term. _The fons et origo of all reality, whether from_ _the absolute or the practical point of view, is thus subjective, is ourselves._ As bare logical thinkers, without emotional reaction, we give reality to whatever objects we think of, for they are really phenomena, or objects of our passing thought, if nothing more. But, _as thinkers with emotional reaction, we give what seems to us a still higher degree of reality to whatever things we select and emphasize and turn to_ WITH A WILL. These are our _living_ realities; and not only these, but all the other things which are intimately connected with these. Reality, starting from our Ego, thus sheds itself from point to point--first, upon all objects which have an immediate sting of interest for our Ego in them, and next, upon the objects most continuously related with these. It only fails when the connecting thread is lost. A whole system may be real, if it only hang to our Ego by one immediately _stinging_ term. But what contradicts any such stinging term, even though it be another stinging term itself, is either not believed, or only believed after settlement of the dispute.

      *       *       *       *       *

We reach thus the important conclusion that _our own reality, that sense of our own life which we at every moment possess, is the ultimate of ultimates for our belief._ 'As sure as I exist!'--this is our uttermost warrant for the being of all other things. As Descartes made the indubitable reality of the _cogito_ go bail for the reality of all that the _cogito_ involved, so we all of us, feeling our own present reality with absolutely coercive force, ascribe an all but equal degree of reality, first to whatever things we lay hold on with a sense of personal need, and second, to whatever farther things continuously belong with these. "Mein Jetzt und Hier," as Prof. Lipps says, "ist der letzte Angelpunkt für alle Wirklichkeit, also alle Erkenntniss."

The world of living realities as contrasted with unrealities is thus anchored in the Ego, considered as an active and emotional term.[302] That is the hook from which the rest dangles, the absolute support. And as from a painted hook it has been said that one can only hang a painted chain, so conversely, from a real hook only a real chain can properly be hung. _Whatever things have intimate and continuous connection with my life are things of whose reality I cannot doubt._ Whatever things fail to establish this connection are things which are practically no better for me than if they existed not at all.

In certain forms of melancholic perversion of the sensibilities and reactive powers, nothing touches us intimately, rouses us, or wakens natural feeling. The consequence is the complaint so often heard from melancholic patients, that nothing is believed in by them as it used to be, and that all sense of reality is fled from life. They are sheathed in india-rubber; nothing penetrates to the quick or draws blood, as it were. According to Griesinger, "I see, I hear!" such patients say, "but the objects do not reach me, it is as if there were a wall between me and the outer world!"

"In such patients there often is an alteration of the cutaneous
sensibility, such that things feel indistinct or sometimes rough
and woolly. But even were this change always present, it would not
completely explain the psychic phenomenon... which reminds us more
of the alteration in our psychic relations to the outer world which
advancing age on the one hand, and on the other emotions and passions,
may bring about. In childhood we feel ourselves to be closer to the
world of sensible phenomena, we live immediately with them and in
them; an intimately vital tie binds us and them together. But with
the ripening of reflection this tie is loosened, the warmth of our
interest cools, things look differently to us, and we act more as
foreigners to the outer world, even though we know it a great deal
better. Joy and expansive emotions in general draw it nearer to us
again. Everything makes a more lively impression, and with the quick
immediate return of this warm receptivity for sense impressions, joy
makes us feel young again. In depressing emotions it is the other
way. Outer things, whether living or inorganic, suddenly grow cold
and foreign to us, and even our favorite objects of interest feel as
if they belonged to us no more. Under these circumstances, receiving
no longer from anything a lively impression, we cease to turn
towards outer things, and the sense of inward loneliness grows upon
us.... Where there is no strong intelligence to control this _blasé_
condition, this psychic coldness and lack of interest, the issue of
these states in which all seems so cold and hollow, the heart dried
up, the world grown dead and empty, is often suicide or the deeper
forms of insanity."[303]


THE PARAMOUNT REALITY OF SENSATIONS.


But now we are met by questions of detail. What does this stirring, this exciting power, this interest, consist in, which some objects have? which _are_ those 'intimate relations' with our life which give reality? And what things stand in these relations immediately, and what others are so closely connected with the former that (in Hume's language) we 'carry our disposition' also on to them?

In a simple and direct way these questions cannot be answered at all. The whole history of human thought is but an unfinished attempt to answer them. For what have men been trying to find out, since men were men, but just those things: "Where do our true interests lie--which relations shall we call the intimate and real ones--which things shall we call living realities and which not?" A few psychological points can, however, be made clear.

_Any relation to our mind at all, in the absence of a stronger relation, suffices to make an object real._ The barest appeal to our attention is enough for that. Revert to the beginning of the chapter, and take the candle entering the vacant mind. The mind was waiting for just some such object to make its spring upon. It makes its spring and the candle is believed. But when the candle appears at the same time with other objects, it must run the gauntlet of their rivalry, and then it becomes a question which of the various candidates for attention shall compel belief. As a rule we believe as much as we can. We would believe everything if we only could. When objects are represented by us quite unsystematically they conflict but little with each other, and the number of them which in this chaotic manner we can believe is limitless. The primitive savage's mind is a jungle in which hallucinations, dreams, superstitions, conceptions, and sensible objects all flourish alongside of each other, unregulated except by the attention turning in this way or in that. The child's mind is the same. It is only as objects become permanent and their relations fixed that discrepancies and contradictions are felt and must be settled in some stable way. As a rule, the success with which a contradicted object maintains itself in our belief is proportional to several qualities which it must possess. Of these the one which would be put first by most people, because it characterizes objects of sensation, is its--

(1) Coerciveness over attention, or the mere power to possess consciousness: then follow--

(2) Liveliness, or sensible pungency, especially in the way of exciting pleasure or pain;

(3) Stimulating effect upon the will, i.e., capacity to arouse active impulses, the more instinctive the better;

(4) Emotional interest, as object of love, dread, admiration, desire, etc.;

(5) Congruity with certain favorite forms of contemplation--unity, simplicity, permanence, and the like;

(6) Independence of other causes, and its own causal importance.

These characters run into each other. Coerciveness is the result of liveliness or emotional interest. What is lively and interesting stimulates _eo ipso_ the will; congruity holds of active impulses as well as of contemplative forms; causal independence and importance suit a certain contemplative demand, etc. I will therefore abandon all attempt at a formal treatment, and simply proceed to make remarks in the most convenient order of exposition.

      *       *       *       *       *

As a whole, sensations are more lively and are judged more real than conceptions; things met with every hour more real than things seen once; attributes perceived when awake, more real than attributes perceived in a dream. But, owing to the _diverse relations contracted by the various objects with each other,_ the simple rule that the lively and permanent is the real is often enough disguised. A conceived thing may be deemed more real than a certain sensible thing, if it only be intimately related to other sensible things more vivid, permanent, or interesting than the first one. Conceived molecular vibrations, e.g., are by the physicist judged more real than felt warmth, because so intimately related to all those other facts of motion in the world which he has made his special study. Similarly, a rare thing may be deemed more real than a permanent thing if it be more widely related to other permanent things. All the occasional crucial observations of science are examples of this. A rare experience, too, is likely to be judged more real than a permanent one, if it be more interesting and exciting. Such is the sight of Saturn through a telescope; such are the occasional insights and illuminations which upset our habitual ways of thought.

But no mere floating conception, no mere disconnected rarity, ever displaces vivid things or permanent things from our belief. A conception, to prevail, must _terminate_ in the world of orderly sensible experience. A rare phenomenon, to displace frequent ones, must belong with others more frequent still. The history of science is strewn with wrecks and ruins of theory--essences and principles, fluids and forces--once fondly clung to, but found to hang together with no facts of sense. And exceptional phenomena solicit our belief in vain until such time as we chance to conceive them as of kinds already admitted to exist. What science means by 'verification' is no more than this, that no object of conception shall be believed which sooner or later has not some permanent and vivid object of sensation for its _term_. Compare what was said on pages 3-7, above.

_Sensible objects are thus either our realities or the tests of our realities. Conceived objects must show sensible effects or else be disbelieved._ And the effects, even though reduced to relative unreality when their causes come to view (as heat, which molecular vibrations make unreal), are yet the things on which our knowledge of the causes rests. Strange mutual dependence this, in which the appearance needs the reality in order to exist, but the reality needs the appearance in order to be known!

_Sensible vividness or pungency is then the vital factor in reality when once the conflict between objects, and the connecting of them together in the mind, has begun._ No object which neither possesses this vividness in its own right nor is able to borrow it from anything else has a chance of making headway against vivid rivals, or of rousing in us that reaction in which belief consists. On the vivid objects we _pin_, as the saying is, our faith in all the rest; and out belief returns instinctively even to those of them from which reflection has led it away. Witness the obduracy with which the popular world of colors, sounds, and smells holds its own against that of molecules and vibrations. Let the physicist himself but nod, like Homer, and the world of sense becomes his absolute reality again.[304]

That things originally devoid of this stimulating power should be enabled, by association with other things which have it, to compel our belief as if they had it themselves, is a remarkable psychological fact, which since Hume's time it has been impossible to overlook.

"The vividness of the first conception," he writes, "diffuses itself
along the relations and is conveyed, as by so many pipes or channels,
to every idea that has any communication with the primary one....
Superstitious people are fond of the relics of saints and holy men,
for the same reason that they seek after types and images, in order
to enliven their devotion and give them a more intimate and strong
conception of those exemplary lives.... Now, 'tis evident one of
the best relics a devotee could procure would be the handiwork of a
saint, and if his clothes and furniture are ever to be considered in
this light, 'tis because they were once at his disposal, and were
moved and affected by him; in which respect they are... connected
with him by a shorter train of consequences than any of those from
which we learn the reality of his existence. This phenomenon clearly
proves that a present impression, with a relation of causation,
may enliven any idea, and consequently produce belief or assent,
according to the precedent definition of it.... It has been remarked
among the Mahometans as well as Christians that those pilgrims who
have seen Mecca or the Holy Land are ever after more faithful and
zealous believers than those who have not had that advantage. A man
whose memory presents him with a lively image of the Red Sea and the
Desert and Jerusalem and Galilee can never doubt of any miraculous
events which are related either by Moses or the Evangelists. The
lively idea of the places passes by an easy transition to the facts
which are supposed to have been related to them by contiguity, and
increases the belief by increasing the vivacity of the conception. The
remembrance of those fields and rivers has the same influence as a new
argument.... The ceremonies of the Catholic religion may be considered
as instances of the same nature. The devotees of that strange
superstition usually plead in excuse for the mummeries with which they
are upbraided that they feel the good effect of external motions and
postures and actions in enlivening their devotion and quickening their
fervor, which otherwise would decay, if directed entirely to distant
and immaterial objects. We shadow out the objects of our faith, say
they, in sensible types and images, and render them more present to us
by the immediate presence of these types than it is possible for us to
do merely by an intellectual view and contemplation."[305]

Hume's cases are rather trivial; and the things which associated sensible objects make us believe in are supposed by him to be unreal. But all the more manifest for that is the fact of their psychological influence. Who does not 'realize' more the fact of a dead or distant friend's existence, at the moment when a portrait, letter, garment or other material reminder of him is found? The whole notion of him then grows pungent and speaks to us and shakes us, in a manner unknown at other times. In children's minds, fancies and realities live side by side. But however lively their fancies may be, they still gain help from association with reality. The imaginative child identifies its _dramatis personæ_ with some doll or other material object, and this evidently solidifies belief, little as it may resemble what it is held to stand for. A thing not too interesting by its own real qualities generally does the best service here. The most useful doll I ever saw was a large cucumber in the hands of a little Amazonian-Indian girl; she nursed it and washed it and rocked it to sleep in a hammock, and talked to it all day long--there was no part in life which the cucumber did not play. Says Mr. Tylor:

"An imaginative child will make a dog do duty for a horse, or a
soldier for a shepherd, till at last the objective resemblance almost
disappears, and a bit of wood may be dragged about, resembling a ship
on the sea or a coach on the road. Here the likeness of the bit of
wood to a ship or coach is very slight indeed; but it is a thing, and
can be moved about,... and is an evident assistance to the child in
enabling it to arrange and develop its ideas.... Of how much use...
may be seen by taking it away, and leaving the child nothing to play
with.... In later years and among highly educated people the mental
process which goes on in a child's playing with wooden soldiers and
horses, though it never disappears, must be sought for in more complex
phenomena. Perhaps nothing in after-life more closely resembles the
effect of a doll upon a child than the effect of the illustrations
of a tale upon a grown reader. Here the objective resemblance is
very indefinite... yet what reality is given to the scene by a good
picture.... Mr. Backhouse one day noticed in Van Diemen's Land a woman
arranging several stones that were flat, oval, and about two inches
wide, and marked in various directions with black and red lines.
These, he learned, represented absent friends, and one larger than the
rest stood for a fat native woman on Flinder's Island, known by the
name of Mother Brown. Similar practices are found among far higher
races than the ill-fated Tasmanians. Among some North American tribes
a mother who has lost a child keeps its memory ever present to her by
filling its cradle with black feathers and quills, and carrying it
about with her for a year or more. When she stops anywhere, she sets
up the cradle and talks to it as she goes about her work, just as she
would have done if the dead body had been still alive within it. Here
we have an image; but in Africa we find a rude doll representing the
child, kept as a memorial.... Bastian saw Indian women in Peru who
had lost an infant carrying about on their backs a wooden doll to
represent it."[306]

To many persons among us, photographs of lost ones seem to be fetishes. They, it is true, resemble; but the fact that the mere materiality of the reminder is almost as important as its resemblance is shown by the popularity a hundred years ago of the black taffeta 'silhouettes' which are still found among family relics, and of one of which Fichte could write to his affianced: '_Die Farbe fehlt, das Auge fehlt, es fehlt der himmlische Ausdruck deiner lieblichen Züge_'--and yet go on worshipping it all the same. The opinion so stoutly professed by many, that language is essential to thought, seems to have this much of truth in it, that all our inward images tend invincibly to attach themselves to something sensible, so as to gain in corporeity and life. Words serve this purpose, gestures serve it, stones, straws, chalk-marks, anything will do. As soon as anyone of these things stands for the idea, the latter seems to be more real. Some persons, the present writer among the number, can hardly lecture without a blackboard: the abstract conceptions must be symbolized by letters, squares or circles, and the relations between them by lines. All this symbolism, linguistic, graphic, and dramatic, has other uses too, for it abridges thought and fixes terms. But one of its uses is surely to rouse the believing reaction and give to the ideas a more living reality. As, when we are told a story, and shown the very knife that did the murder, the very ring whose hiding-place the clairvoyant revealed, the whole thing passes from fairy-land to mother-earth, so here we believe all the more, if only we see that 'the bricks are alive to tell the tale.'

      *       *       *       *       *

So much for the prerogative position of sensations in regard to our belief. But among the sensations themselves all are not deemed equally real. The more practically important ones, the more permanent ones, and the more æsthetically apprehensible ones are selected from the mass, to be believed in most of all; the others are degraded to the position of mere signs and suggestions of these. This fact has already been adverted to in former chapters.[307] The real color of a thing is that one color-sensation which it gives us when most favorably lighted for vision. So of its real size, its real shape, etc.--these are but optical sensations selected out of thousands of others, because they have æsthetic characteristics which appeal to our convenience or delight. But I will not repeat what I have already written about this matter, but pass on to our treatment of tactile and muscular sensations, as 'primary qualities,' more real than those 'secondary' qualities which eye and ear and nose reveal. Why do we thus so markedly select the _tangible_ to be the real? Our motives are not far to seek. The tangible qualities are the least fluctuating. When we get them at all we get them the same. The other qualities fluctuate enormously as our relative position to the object changes. Then, more decisive still, the tactile properties are those most intimately connected with our weal or woe. A dagger hurts us only when in contact with our skin, a poison only when we take it into our mouths, and we can only use an object for our advantage when we have it in our muscular control. It is as tangibles, then, that things concern us most; and the other senses, so far as their practical use goes, do but warn us of what tangible things to expect. They are but organs of anticipatory touch, as Berkeley has with perfect clearness explained.[308]

Among all sensations, the _most_ belief-compelling are those productive of pleasure or of pain. Locke expressly makes the _pleasure_- or _pain_-giving quality to be the ultimate human criterion of anything's reality. Discussing (with a supposed Berkeleyan before Berkeley) the notion that all our perceptions may be but a dream, he says:

"He may please to dream that I make him this answer... that I believe
he will allow a very manifest difference between dreaming of being in
the fire and being actually in it. But yet if he be resolved to appear
so sceptical as to maintain that what I call being actually in the
fire is nothing but a dream, and that we cannot thereby certainly know
that any such thing as fire actually exists without us, I answer that
we, certainly finding that pleasure or pain [or emotion of any sort]
follows upon the application of certain objects to us, whose existence
we perceive, or dream that we perceive by our senses, _this certainly
is as great as our happiness or misery,_ beyond which we have no
concernment to know or to be."[309]


THE INFLUENCE OF EMOTION AND ACTIVE IMPULSE ON BELIEF.


The quality of arousing emotion, of shaking, moving us or inciting us to action, has as much to do with our belief in an object's reality as the quality of giving pleasure or pain. In Chapter XXIV I shall seek to show that our emotions probably owe their pungent quality to the bodily sensations which they involve. Our tendency to believe in emotionally exciting objects (objects of fear, desire, etc.) is thus explained without resorting to any fundamentally new principle of choice. Speaking generally, the more a conceived object _excites_ us, the more reality it has. The same object excites us differently at different times. Moral and religious truths come 'home' to us far more on some occasions than on others. As Emerson says, "There is a difference between one and another hour of life in their authority and subsequent effect. Our faith comes in moments,... yet there is a depth in those brief moments which constrains us to ascribe more reality to them than to all other experiences." The 'depth' is partly, no doubt, the insight into wider systems of unified relation, but far more often than that it is the emotional thrill. Thus, to descend to more trivial examples, a man who has no belief in ghosts by daylight will temporarily believe in them when, alone at midnight, he feels his blood curdle at a mysterious sound or vision, his heart thumping, and his legs impelled to flee. The thought of falling when we walk along a curbstone awakens no emotion of dread; so no sense of reality attaches to it, and we are sure we shall not fall. On a precipice's edge, however, the sickening emotion which the notion of a possible fall engenders makes us believe in the latter's imminent reality, and quite unfits us to proceed.

The greatest proof that a man is _sui compos_ is his ability to suspend belief in presence of an emotionally exciting idea. To give this power is the highest result of education. In untutored minds the power does not exist. _Every exciting thought in the natural man carries credence with it. To conceive with passion is eo ipso to affirm._ As Bagehot says:

"The Caliph Omar burnt the Alexandrian Library, saying: 'All books
which contain what is not in the Koran are dangerous. All which
contain what is in it are useless!' Probably no one ever had an
intenser belief in anything than Omar had in this. Yet it is
impossible to imagine it preceded by an argument. His belief in
Mahomet, in the Koran, and in the sufficiency of the Koran, probably
came to him in spontaneous rushes of emotion; there may have been
little vestiges of argument floating here and there, but they did
not justify the strength of the emotion, still less did they create
it, and they hardly even excused it.... Probably, when the subject
is thoroughly examined, conviction will be found to be one of the
intensest of human emotions, and one most closely connected with the
bodily state,... accompanied or preceded by the sensation that Scott
makes his seer describe as the prelude of a prophecy:
   'At length the fatal answer came,
   In characters of living flame--
   Not spoke in words, nor blazed in scroll,
   But borne and branded on my soul.'
A hot flash seems to burn across the brain. Men in these intense
states of mind have altered all history, changed for better or worse
the creed of myriads, and desolated or redeemed provinces or ages. Nor
is this intensity a sign of truth, for it is precisely strongest in
those points in which men differ most from each other. John Knox felt
it in his anti-Catholicism; Ignatius Loyola in his anti-Protestantism;
and both, I suppose, felt it as much as it is possible to feel
it."[310]

The reason of the belief is undoubtedly the bodily commotion which the exciting idea sets up. 'Nothing which I can feel like _that_ can be false.' All our religious and supernatural beliefs are of this order. The surest warrant for immortality is the yearning of our bowels for our dear ones; for God, the sinking sense it gives us to imagine no such Providence or help. So of our political or pecuniary hopes and fears, and things and persons dreaded and desired. "A grocer has a full creed as to foreign policy, a young lady a complete theory of the sacraments, as to which neither has any doubt.... A girl in a country parsonage will be sure that Paris never can be taken, or that Bismarck is a wretch"--all because they have either conceived these things at some moment with passion, or associated them with other things which they have conceived with passion.

M. Renouvier calls this belief of a thing for no other reason than that we conceive it with passion, by the name of _mental vertigo_.[311] Other objects whisper doubt or disbelief; but the object of passion makes us deaf to all but itself, and we affirm it unhesitatingly. Such objects are the delusions of insanity, which the insane person can at odd moments steady himself against, but which again return to sweep him off his feet. Such are the revelations of mysticism. Such, particularly, are the sudden beliefs which animate mobs of men when frenzied impulse to action is involved. Whatever be the action in point--whether the stoning of a prophet, the hailing of a conqueror, the burning of a witch, the baiting of a heretic or Jew, the starting of a forlorn hope, or the flying from a foe--the fact that to believe a certain object will _cause that action to explode_ is a sufficient reason for that belief to come. The motor impulse sweeps it unresisting in its train.

The whole history of witchcraft and early medicine is a commentary on the facility with which anything which chances to be conceived is believed the moment the belief chimes in with an emotional mood. 'The cause of sickness?' When a savage asks the cause of anything he means to ask exclusively 'What is to blame?' The theoretic curiosity starts from the practical life's demands. Let some one then accuse a necromancer, suggest a charm or spell which has been cast, and no more 'evidence' is asked for. What evidence is required beyond this intimate sense of the culprit's responsibility, to which our very viscera and limbs reply?[312]

Human credulity in the way of therapeutics has similar psychological roots. If there is anything intolerable (especially to the heart of a woman), it is to do nothing when a loved one is sick or in pain. To do anything is a relief. Accordingly, whatever remedy may be suggested is a spark on inflammable soil. The mind makes its spring towards action on that cue, sends for that remedy, and for a day at least believes the danger past. Blame, dread, and hope are thus the great belief-inspiring passions, and cover among them the future, the present, and the past.

These remarks illustrate the earlier heads of the list on page 292. Whichever represented objects give us sensations, especially interesting ones, or incite our motor impulses, or arouse our hate, desire, or fear, are real enough for us. Our requirements in the way of reality terminate in our own acts and emotions, our own pleasures and pains. These are the ultimate fixities from which, as we formerly observed, the whole chain of our beliefs depends, object hanging to object, as the bees, in swarming, hang to each other until, _de proche en proche,_ the supporting branch, the Self, is reached and held.


BELIEF IN OBJECTS OF THEORY.


Now the merely conceived or imagined objects which our mind represents as hanging to the sensations (causing them, etc.), filling the gaps between them, and weaving their interrupted chaos into order are innumerable. Whole systems of them conflict with other systems, and our choice of which system shall carry our belief is governed by principles which are simple enough, however subtle and difficult may be their application to details. _The conceived system, to pass for true, must at least include the reality of the sensible objects in it, by explaining them as effects on us, if nothing more. The system which includes the most of them, and definitely explains or pretends to explain the most of them, will, ceteris paribus, prevail._ It is needless to say how far mankind still is from having excogitated such a system. But the various materialisms, idealisms, and hylozoisms show with what industry the attempt is forever made. It is conceivable that several rival theories should equally well include the actual order of our sensations in their scheme, much as the one-fluid and two-fluid theories of electricity formulated all the common electrical phenomena equally well. The sciences are full of these alternatives. Which theory is then to be believed? _That theory will be most generally believed which, besides offering us objects able to account satisfactorily for our sensible experience_, _also offers those which are most interesting, those which appeal most urgently to our æsthetic, emotional, and active needs._ So here, in the higher intellectual life, the same selection among general conceptions goes on which went on among the sensations themselves. First, a word of their relation to our emotional and active needs--and here I can do no better than quote from an article published some years ago:[313]

"A philosophy may be unimpeachable in other respects, but either
of two defects will be fatal to its universal acceptance. First,
its ultimate principle must not be one that essentially baffles
and disappoints our dearest desires and most cherished powers.
A pessimistic principle like Schopenhauer's incurably vicious
Will-substance, or Hartmann's wicked jack-at-all-trades, the
Unconscious, will perpetually call forth essays at other philosophies.
Incompatibility of the future with their desires and active tendencies
is, in fact, to most men a source of more fixed disquietude than
uncertainty itself. Witness the attempts to overcome the 'problem of
evil,' the 'mystery of pain.' There is no problem of 'good.'
"But a second and worse defect in a philosophy than that of
contradicting our active propensities is to give them no Object
whatever to press against. A philosophy whose principle is so
incommensurate with our most intimate powers as to deny them all
relevancy in universal affairs, as to annihilate their motives at
one blow, will be even more unpopular than pessimism. Better face
the enemy than the eternal Void! This is why materialism will always
fail of universal adoption, however well it may fuse things into an
atomistic unity, however clearly it may prophesy the future eternity.
For materialism denies reality to the objects of almost all the
impulses which we most cherish. The real _meaning_ of the impulses, it
says, is something which has no emotional interest for us whatever.
But what is called extradition is quite as characteristic of our
emotions as of our sense. Both point to an Object as the cause of the
present feeling. What an intensely objective reference lies in fear!
In like manner an enraptured man, a dreary-feeling man, are not simply
aware of their subjective states; if they were, the force of their
feelings would evaporate. Both believe there is outward cause _why_
they should feel as they do: either 'It is a glad world! how good
is life!' or 'What a loathsome tedium is existence!' Any philosophy
which annihilates the validity of the reference by explaining away
its objects or translating them into terms of no emotional pertinency
leaves the mind with little to care or act for. This is the opposite
condition from that of nightmare, but when acutely brought home to
consciousness it produces a kindred horror. In nightmare we have
motives to act, but no power; here we have powers, but no motives.
A nameless _Unheimlichkeit_ comes over us at the thought of there
being nothing eternal in our final purposes, in the objects of those
loves and aspirations which are our deepest energies. The monstrously
lopsided equation of the universe and its knower, which we postulate
as the ideal of cognition, is perfectly paralleled by the no less
lopsided equation of the universe and the _doer_. We demand in it
a _character_ for which our emotions and active propensities shall
be a match. Small as we are, minute as is the point by which the
Cosmos impinges upon each one of us, each one desires to feel that
his reaction at that point is congruous with the demands of the vast
whole, that he balances the latter, so to speak, and is able to do
what it expects of him. But as his abilities to 'do' lie wholly in
the line of his natural propensities; as he enjoys reaction with such
emotions as fortitude, hope, rapture, admiration, earnestness, and the
like; and as he very unwillingly reacts with fear, disgust, despair,
or doubt,--a philosophy which should legitimate only emotions of the
latter sort would be sure to leave the mind a prey to discontent and
craving.
"It is far too little recognized how entirely the intellect is built
up of practical interests. The theory of Evolution is beginning to do
very good service by its reduction of all mentality to the type of
reflex action. Cognition, in this view, is but a fleeting moment, a
cross-section at a certain point of what in its totality is a motor
phenomenon. In the lower forms of life no one will pretend that
cognition is anything more than a guide to appropriate action. The
germinal question concerning things brought for the first time before
consciousness is not the theoretic 'What is that?' but the practical
'Who goes there?' or rather, as Horwicz has admirably put it, 'What
is to be done?'--'_Was fang' ich an_?' In all our discussions about
the intelligence of lower animals the only test we use is that of
their _acting_ as if for a purpose. Cognition, in short, is incomplete
until discharged in act. And although it is true that the later mental
development, which attains its maximum through the hypertrophied
cerebrum of man, gives birth to a vast amount of theoretic activity
over and above that which is immediately ministerial to practice,
yet the earlier claim is only postponed, not effaced, and the active
nature asserts its rights to the end.
"If there be any truth at all in this view, it follows that however
vaguely a philosopher may define the ultimate universal datum,
he cannot be said to leave it unknown to us so long as he in the
slightest degree pretends that our emotional or active attitude
towards it should be of one sort rather than another. He who says,
'Life is real, life is earnest,' however much he may speak of the
fundamental mysteriousness of things, gives a distinct definition to
that mysteriousness by ascribing to it the right to claim from us the
particular mood called seriousness, which means the willingness to
live with energy, though energy bring pain. The same is true of him
who says that all is vanity. Indefinable as the predicate vanity may
be _in se_, it is clearly enough something which permits anæsthesia,
mere escape from suffering, to be our rule of life. There is no more
ludicrous incongruity than for agnostics to proclaim with one breath
that the substance of things is unknowable, and with the next that
the thought of it should inspire us with admiration of its glory,
reverence, and a willingness to add our co-operative push in the
direction towards which its manifestations seem to be drifting. The
unknowable may be unfathomed, but if it make such distinct demands
upon our activity, we surely are not ignorant of its essential quality.
"If we survey the field of history and ask what feature all great
periods of revival, of expansion of the human mind, display in common,
we shall find, I think, simply this: that each and all of them
have said to the human being, 'The inmost nature of the reality is
congenial to _powers_ which you possess.' In what did the emancipating
message of primitive Christianity consist, but in the announcement
that God recognizes those weak and tender impulses which paganism had
so rudely overlooked? Take repentance: the man who can do nothing
rightly can at least repent of his failures. But for paganism this
faculty of repentance was a pure supernumerary, a straggler too late
for the fair. Christianity took it and made it the one power within
us which appealed straight to the heart of God. And after the night
of the Middle Ages had so long branded with obloquy even the generous
impulses of the flesh, and defined the Reality to be such that only
slavish natures could commune with it, in what did the _Sursum corda!_
of the Renaissance lie but in the proclamation that the archetype
of verity in things laid claim on the widest activity of our whole
æsthetic being? What were Luther's mission and Wesley's but appeals
to powers which even the meanest of men might carry with them, faith
and self-despair, but which were personal, requiring no priestly
intermediation, and which brought their owner face to face with God?
What caused the wild-fire influence of Rousseau but the assurance he
gave that man's nature was in harmony with the nature of things, if
only the paralyzing corruptions of custom would stand from between?
How did Kant and Fichte, Goethe and Schiller, inspire their time
with cheer, except by saying, 'Use all your powers; that is the only
obedience which the universe exacts'? And Carlyle with his gospel of
Work, of Fact, of Veracity, how does he move us except by saying that
the universe imposes no tasks upon us but such as the most humble can
perform? Emerson's creed that everything that ever was or will be is
here in the enveloping Now; that man has but to obey himself--'He who
will rest in what he _is_, is a part of Destiny'--is in like manner
nothing but an exorcism of all scepticism as to the pertinency of
one's natural faculties.
"In a word, 'Son of Man, _stand upon thy feet_ and I will speak unto
thee!' is the only revelation of truth to which the solving epochs
have helped the disciple. But that has been enough to satisfy the
greater part of his rational need. _In se_ and _per se_ the universal
essence has hardly been more defined by any of these formulæ than by
the agnostic _x_; but the mere assurance that my powers, such as they
are, are not irrelevant to it, but pertinent, that it speaks to them
and will in some way recognize their reply, that I can be a match for
it if I will, and not a footless waif, suffices to make it rational
to my feeling in the sense given above. Nothing could be more absurd
than to hope for the definitive triumph of any philosophy which should
refuse to legitimate, and to legitimate in an emphatic manner, the
more powerful of our emotional and practical tendencies. Fatalism,
whose solving word in all crises of behavior is 'All striving is
vain,' will never reign supreme, for the impulse to take life
strivingly is indestructible in the race. Moral creeds which speak
to that impulse will be widely successful in spite of inconsistency,
vagueness, and shadowy determination of expectancy. Man needs a rule
for his will, and will invent one if one be not given him."

After the emotional and active needs come the intellectual and æsthetic ones. The two great æsthetic principles, of richness and of ease, dominate our intellectual as well as our sensuous life. And, _ceteris paribus_, no system which should not be rich, simple, and harmonious would have a chance of being chosen for belief, if rich, simple, and harmonious systems were also there. Into the latter we should unhesitatingly settle, with that welcoming attitude of the will in which belief consists. To quote from a remarkable book:

"This law that our consciousness constantly tends to the minimum of
complexity and to the maximum of definiteness, is of great importance
for all our knowledge.... Our own activity of attention will thus
determine what we are to know and what we are to believe. If things
have more than a certain complexity, not only will our limited powers
of attention forbid us to unravel this complexity, but we shall
strongly desire to believe the things much simpler than they are.
For our thoughts about them will have a constant tendency to become
as simple and definite as possible. Put a man into a perfect chaos
of phenomena--sounds, sights, feelings--and if the man continued to
exist, and to be rational at all, his attention would doubtless soon
find for him away to make up some kind of rhythmic regularity, which
he would impute to the things about him, so as to imagine that he had
discovered some laws of sequence in this mad new world. And thus, in
every case where we fancy ourselves sure of a simple law of Nature, we
must remember that a great deal of the fancied simplicity may be due,
in the given case, not to Nature, but to the ineradicable prejudice of
our own minds in favor of regularity and simplicity. All our thoughts
are determined, in great measure, by this law of least effort, as it
is found exemplified in our activity of attention.... The aim of the
whole process seems to be to reach as complete and united a conception
of reality as possible, a conception wherein the greatest fulness of
data shall be combined with the greatest simplicity of conception. The
effort of consciousness seems to be to combine the greatest richness
of content with the greatest definiteness of organization."[314]

The richness is got by including all the facts of sense in the scheme; the simplicity, by deducing them out of the smallest possible number of permanent and independent primordial entities: the definite organization, by assimilating these latter to ideal objects between which relations of an inwardly rational sort obtain. What these ideal objects and rational relations are will require a separate chapter to show.[315] Meanwhile, enough has surely been said to justify the assertion made above that no general off-hand answer can be given as to which objects mankind shall choose as its realities. The fight is still under way. Our minds are yet chaotic; and at best we make a mixture and a compromise, as we yield to the claim of this interest or that, and follow first one and then another principle in turn. It is undeniably true that materialistic, or so-called 'scientific,' conceptions of the universe have so far gratified the purely intellectual interests more than the mere sentimental conceptions have. But, on the other hand, as already remarked, they leave the emotional and active interests cold. _The perfect object of belief would be a God or 'Soul of the World,' represented both optimistically and moralistically (if such a combination could be), and withal so definitely conceived as to show us why our phenomenal experiences should be sent to us by Him in just the very way in which they come._ All Science and all History would thus be accounted for in the deepest and simplest fashion. The very room in which I sit, its sensible walls and floor, and the feeling the air and fire within it give me, no less than the 'scientific' conceptions which I am urged to frame concerning the mode of existence of all these phenomena when my back is turned, would then all be corroborated, not de-realized, by the ultimate principle of my belief. The World-soul sends me just those phenomena in order that I may react upon them; and among the reactions is the intellectual one of spinning these conceptions. What is beyond the crude experiences is not an _alternative_ to them, but something that _means_ them for me here and now. It is safe to say that, if ever such a system is satisfactorily excogitated, mankind will drop all other systems and cling to that one alone as real. Meanwhile the other systems coexist with the attempts at that one, and, all being alike fragmentary, each has its little audience and day.

      *       *       *       *       *

I have now, I trust, shown sufficiently what the psychologic sources of the sense of reality are. Certain postulates are given in our nature; and whatever satisfies those postulates is treated as if real.[316] I might therefore finish the chapter here, were it not that a few additional words will set the truth in a still clearer light.


DOUBT.


There is hardly a common man who (if consulted) would not say that things come to us in the first instance _as ideas_; and that if we take them for realities, it is because we _add something to them_, namely, the predicate of having also '_real existence outside of our thought_.' This notion that a higher faculty than the mere _having_ of a conscious content is needed to make us know anything real by its means has pervaded psychology from the earliest times, and is the tradition of Scholasticism, Kantism, and Common-sense. Just as sensations must come as inward affections and then be 'extradited;' as objects of memory must appear at first as presently unrealities, and subsequently be 'projected' backwards as past realities; so conceptions must be _entia rationis_ till a higher faculty uses them as windows to look beyond the ego, into the real _extra_-mental world;--so runs the orthodox and popular account.

And there is no question that this is a true account of the way in which many of our later beliefs come to pass. The logical distinction between the bare thought of an object and belief in the object's reality is often a chronological distinction as well. The having and the crediting of an idea do not always coalesce; for often we first suppose and then believe; first play with the notion, frame the hypothesis, and then affirm the existence, of an object of thought. And we are quite conscious of the succession of the two mental acts. But these cases are none of them _primitive_ cases. They only occur in minds long schooled to doubt by the contradictions of experience. _The primitive impulse is to affirm immediately the reality of all that is conceived._[317] When we do doubt, however, in what does the subsequent resolution of the doubt consist? It either consists in a purely verbal performance, the coupling of the adjectives 'real' or 'outwardly existing' (as predicates) to the thing originally conceived (as subject); or it consists in the perception in the given case of _that for which these adjectives_, abstracted from other similar concrete cases, _stand_. But what these adjectives stand for, we now know well. They stand for certain relations (immediate, or through intermediaries) to ourselves. Whatever concrete objects have hitherto stood in those relations have been for us 'real,' 'outwardly existing.' So that when we now abstractly admit a thing to be 'real' (without perhaps going through any definite perception of its relations), it is as if we said "it belongs in the same world with those other objects." Naturally enough, we have hourly opportunities for this summary process of belief. All remote objects in space or time are believed in this way. When I believe that some prehistoric savage chipped this flint, for example, the reality of the savage and of his act makes no direct appeal either to my sensation, emotion, or volition. What I mean by my belief in it is simply my dim sense of a _continuity_ between the long dead savage and his doings and the present world of which the flint forms part. It is pre-eminently a case for applying our doctrine of the 'fringe' (see Vol I. p. 258). When I think the savage with one fringe of relationship, I believe in him; when I think him without that fringe, or with another one (as, e.g., if I should class him with 'scientific vagaries' in general), I disbelieve him. The word 'real' itself is, in short, a fringe.


RELATIONS OF BELIEF AND WILL.


We shall see in Chapter XXV that will consists in nothing but a manner of attending to certain objects, or consenting to their stable presence before the mind. The objects, in the case of will, are those whose existence depends on our thought, movements of our own body for example, or facts which such movements executed in future may make real. Objects of belief, on the contrary, are those which do not change according as we think regarding them. I _will_ to get up early to-morrow morning; I _believe_ that I got up late yesterday morning; I _will_ that my foreign bookseller in Boston shall procure me a German book and write to him to that effect. I _believe_ that he will make me pay three dollars for it when it comes, etc. Now the important thing to notice is that this difference between the objects of will and belief is entirely immaterial, as far as the relation of the mind to them goes. All that the mind does is in both cases the same; it looks at the object and consents to its existence, espouses it, says 'it shall be my reality.' It turns to it, in short, in the interested active emotional way. The rest is done by nature, which in some cases _makes_ the objects real which we think of in this manner, and in other cases does not. Nature cannot change the past to suit our thinking. She cannot change the stars or the winds; but she _does_ change our bodies to suit our thinking, and through their instrumentality changes much besides; so the great practical distinction between objects which we may will or unwill, and objects which we can merely believe or disbelieve, grows up, and is of course one of the most important distinctions in the world. Its roots, however, do not lie in psychology, but in physiology; as the chapter on Volition will abundantly make plain. _Will and Belief, in short, meaning a certain relation between objects and the Self, are two names for one and the same_ PSYCHOLOGICAL _phenomenon_. All the questions which arise concerning one are questions which arise concerning the other. The causes and conditions of the peculiar relation must be the same in both. The free-will question arises as regards belief. If our wills are indeterminate, so must our beliefs be, etc. The first act of free-will, in short, would naturally be to believe in free-will, etc. In Chapter XXVI, I shall mention this again.

      *       *       *       *       *

A practical observation may end this chapter. If belief consists in an emotional reaction of the entire man on an object, how _can_ we believe at will? We cannot control our emotions. Truly enough, a man cannot believe at will abruptly. Nature sometimes, and indeed not very infrequently, produces instantaneous conversions for us. She suddenly puts us in an active connection with objects of which she had till then left us cold. "I realize for the first time," we then say, "what that means!" This happens often with moral propositions. We have often heard them; but now they shoot into our lives; they move us; we feel their living force. Such instantaneous beliefs are truly enough not to be achieved by will. But _gradually_ our will can lead us to the same results by a very simple method: _we need only in cold blood_ ACT _as if the thing in question were real, and keep acting as if it were real, and it will infallibly end by growing into such a connection with our life that it will become real._ It will become so knit with habit and emotion that our interests in it will be those which characterize belief. Those to whom 'God' and 'Duty' are now mere names can make them much more than that, if they make a little sacrifice to them every day. But all this is so well known in moral and religious education that I need say no more.[318]

      *       *       *       *       *

[287] Reprinted, with additions, from 'Mind' for July 1889.

[288] Compare this psychological fact with the corresponding logical truth that all negation rests on covert assertion of something else than the thing denied. (See Bradley's Principles of Logic, bk. i. ch. 3.)

[289] See that very remarkable little work, 'The Anæsthetic Revelation and the Gist of Philosophy,' by Benj. P. Blood (Amsterdam, N. Y., 1874). Compare also Mind, vii. 206.

[290] "To one whose mind is healthy thoughts come and go unnoticed; with me they have to be faced, thought about in a peculiar fashion, and then disposed of as finished, and this often when I am utterly wearied and would be at peace; but the call is imperative. This goes on to the hindrance of all natural action. If I were told that the staircase was on fire and I had only a minute to escape, and the thought arose--'Have they sent for fire-engines? Is it probable that the man who has the key is on hand? Is the man a careful sort of person? Will the key be hanging on a peg? Am I thinking rightly? Perhaps they don't lock the depot'--my foot would be lifted to go down; I should be conscious to excitement that I was losing my chance; but I should be unable to stir until all these absurdities were entertained and disposed of. In the most critical moments of my life, when I ought to have been so _engrossed as to leave no room for any secondary thoughts_, I have been oppressed by the inability to be at peace. And in the most ordinary circumstances it is all the same. Let me instance the other morning I went to walk. The day was biting cold, but I was unable to proceed except by jerks. Once I got arrested, my feet in a muddy pool. One foot was lifted to go, knowing that it was not good to be standing in water, but there I was fast, the cause of detention being the discussing with myself the reasons why I should not stand in that pool." (T. S. Clouston, Clinical Lectures on Mental Diseases, 1883, p. 43. See also Berger, in Archiv f. Psychiatrie, vi. 217.)

[291] Note to Jas. Mill's Analysis, i. 412-428.

[292] For an excellent account of the history of opinion on this subject see A. Marty, in Vierteljahrsch. f. wiss. Phil., viii. 181 ff. (1884).

[293] We saw near the end of Chapter XIX that a candle-image taking exclusive possession of the mind in this way would probably acquire the sensational vividness. But this physiological accident is logically immaterial to the argument in the text, which ought to apply as well to the dimmest sort of mental image as to the brightest sensation.

[294] In both existential and attributive judgments a synthesis is represented. The syllable _ex_ in the word Existence, _da_ in the word _Dasein_, express it. 'The candle exists' is equivalent to 'The candle is _over there_.' And the 'over there' means real space, space related to other reals. The proposition amounts to saying: 'The candle is in the same space with other reals.' It affirms of the candle a very concrete predicate--namely, this relation to other particular concrete things. _Their_ real existence, as we shall later see, resolves itself into their peculiar relation to _ourselves_. Existence is thus no substantive quality when we predicate it of any object; it is a relation, ultimately terminating in ourselves, and at the moment when it terminates, becoming a _practical_ relation. But of this more anon. I only wish now to indicate the superficial nature of the distinction between the existential and the attributive proposition.

[295] I define the scientific universe here in the radical mechanical way. Practically, it is oftener thought of in a mongrel way and resembles in more points the popular physical world.

[296] It thus comes about that we can say such things as that Ivanhoe did not _really_ marry Rebecca, as Thackeray _falsely_ makes him do. The real Ivanhoe-world is the one which Scott wrote down for us. _In that world_ Ivanhoe does _not_ marry Rebecca. The objects within that world are knit together by perfectly definite relations, which can be affirmed or denied. Whilst absorbed in the novel, we turn our backs on all other worlds, and, for the time, the Ivanhoe-world remains our absolute reality. When we wake from the spell, however, we find a still more real world, which reduces Ivanhoe, and all things connected with him, to the Active status, and relegates them to one of the sub-universes grouped under No. 5.

[297] The world of dreams is our real world whilst we are sleeping, because our attention then lapses from the sensible world. Conversely, when we wake the attention usually lapses from the dream-world and that becomes unreal. But if a dream haunts us and compels our attention during the day it is very apt to remain figuring in our consciousness as a sort of sub-universe alongside of the waking world. Most people have probably had dreams which it is hard to imagine not to have been glimpses into an actually existing region of being, perhaps a corner of the 'spiritual world.' And dreams have accordingly in all ages been regarded as revelations, and have played a large part in furnishing forth mythologies and creating themes for faith to lay hold upon. The 'larger universe,' here, which helps us to believe both in the dream and in the waking reality which is its immediate reductive, is the _total_ universe, of Nature _plus_ the Supernatural. The dream holds true, namely, in one half of that universe; the waking perceptions in the other half. Even to-day dream-objects figure among the realities in which some 'psychic-researchers' are seeking to rouse our belief. All our theories, not only those about the supernatural, but our philosophic and scientific theories as well, are like our dreams in rousing such different degrees of belief in different minds.

[298] Distinguishes realities from unrealities, the essential from the rubbishy and neglectable.

[299] Inquiry concerning Hum. Understanding, sec. v. pt. 2 (slightly transposed in my quotation).

[300] Note to Jas. Mill's Analysis, i. 394.

[301] Critique of Pure Reason, trans. Müller, ii. 515-17. Hume also: "When, after the simple conception of anything, we would conceive it as existent, we in reality make no addition to, or alteration of, our first idea. Thus, when we affirm that God is existent, we simply form the idea of such a being as He is represented to us; nor is the existence which we attribute to Him conceived by a particular idea, which we join to His other qualities, and can again separate and distinguish from them.... The belief of the existence joins no new idea to those which compose the ideas of the object. When I think of God, when I think of Him as existent, and when I believe Him to be existent, my idea of Him neither increases nor diminishes. But as 'tis certain there is a great difference betwixt the simple conception of the existence of an object and the belief of it, and as this difference lies not in the facts or compositions of the idea which we conceive, it follows that it must lie in the manner in which we conceive it." (Treatise of Human Nature, pt. iii. sec. 7.)

[302] I use the notion of the Ego here, as common-sense uses it. Nothing is prejudged as to the results (or absence of results) of ulterior attempts to analyze the notion.

[303] Griesinger, Mental Diseases, §§ 50, 98. The neologism we so often hear, that an experience 'gives us a _realising sense_' of the truth of some proposition or other, illustrates the dependence of the sense of reality upon _excitement_. Only what stirs us is 'realized.'

[304] The way in which sensations are pitted against systematized conceptions, and in which the one or the other then prevails according as the sensations are felt by ourselves or merely known by report, is interestingly illustrated at the present day by the state of public belief about 'spiritualistic' phenomena. There exist numerous narratives of movement without contact on the part of articles of furniture and other material objects, in the presence of certain privileged individuals called mediums. Such movement violates our memories, and the whole system of accepted physical 'science.' Consequently those who have not seen it either brand the narratives immediately as lies or call the phenomena 'illusions' of sense, produced by fraud or due to hallucination. But one who has actually seen such a phenomenon, under what seems to him sufficiently 'test-conditions,' will hold to his sensible experience through thick and thin, even though the whole fabric of 'science' should be rent in twain. That man would be a weak-spirited creature indeed who should allow any fly-blown generalities about 'the liability of the senses to be deceived' to bully him out of his adhesion to what for him was an indubitable experience of sight. A man may err in this obstinacy, sure enough, in any particular case. But the spirit that animates him is that on which ultimately the very life and health of Science rest.

[305] Treatise of Human Nature, bk. i. pt. iii. sec. 7.

[306] Early Hist. of Mankind, p. 108.

[307] See Vol. I. pp. 285-6; Vol. II. pp. 237 ff.

[308] See Theory of Vision, § 59.

[309] Essay, bk. iv. chap. 2, § 14. In another place: "He that sees a candle burning and hath experimented the force of its flame by putting his finger into it, will little doubt that this is something existing without him, which does him harm and puts him to great pain.... And if our dreamer pleases to try whether the glowing heat of a glass furnace be barely a wandering imagination in a drowsy man's fancy by putting his hand into it, he may, perhaps, be awakened into a certainty greater than he could wish, that it is something more than bare imagination. So that the evidence is as great as we can desire, being as certain to us as our pleasure or pain, i.e. happiness or misery; beyond which we have no concernment, either of knowledge or being. Such an assurance of the existence of things without us is sufficient to direct us in the attaining the good and avoiding the evil which is caused by them, which is the important concernment we have of being made acquainted with them," (_Ibid._ bk. iv. chap. 11, § 8.)

[310] W. Bagehot, 'The Emotion of Conviction,' Literary Studies, i. 412-17.

[311] Psychologie Rationnelle, ch. 12.

[312] Two examples out of a thousand:

Reid, Inquiry, ch. ii. § 9: "I remember, many years ago, a white ox was brought into the country, of so enormous size that people came many miles to see him. There happened, some months after, an uncommon fatality among women in child-hearing. Two such uncommon events, following one another, gave a suspicion of their connection, and occasioned a common opinion among the country people that the white ox was the cause of this fatality."

H. M. Stanley, Through the Dark Continent, ii. 388: "On the third day of our stay at Mowa, feeling quite comfortable amongst the people, on account of their friendly bearing, I began to write in my note-book the terms for articles, in order to improve my already copious vocabulary of native words. I had proceeded only a few minutes when I observed a strange commotion amongst the people who had been flocking about me, and presently they ran away. In a short time we heard war-cries ringing loudly and shrilly over the table-land. Two hours afterwards a long line of warriors were seen descending the table-land and advancing towards our camp. There may have been between five and six hundred of them. We, on the other hand, had made but few preparations except such as would justify us replying to them in the event of the actual commencement of hostilities. But I had made many firm friends among them, and I firmly believed that I should be able to avert an open rupture. When they had assembled at about a hundred yards in front of our camp, Safeni and I walked up towards them and sat down midway. Some half-dozen of the Mowa people came near, and the shauri began.

"'What is the matter, my friends?' I asked. 'Why do you come with guns in your hands, in such numbers, as though you were coming to fight? Fight? fight us, your friends! Tut! this is some great mistake, surely.'

"'Mundele,' replied one of them,... 'our people saw you yesterday make marks on some tara-tara [paper]. This is very bad. Our country will waste, our goats will die, our bananas will rot, and our women will dry up. What have we done to you that you should wish to kill us? We have sold you food and we have brought you wine each day. Your people are allowed to wander where they please without trouble. Why is the Mundele so wicked? We have gathered together to fight you if you do not burn that tara-tara now before our eyes. If you burn it we go away, and shall be your friends as heretofore.'

"'I told them to rest there, and left Safeni in their hands as a pledge that I should return. My tent was not fifty yards from the spot, but while going towards it my brain was busy in devising some plan to foil this superstitious madness. My note-book contained a vast number of valuable notes.... I could not sacrifice it to the childish caprice of savages. As I was rummaging my book-box, I came across a volume of Shakespeare [Chandos edition] much worn, and well thumbed, and which was of the same size as my field-book; its cover was similar also, and it might be passed for the field-book, provided that no one remembered its appearance too well. I took it to them. 'Is this the tara-tara, friends, that you wish burned?'

"'Yes, yes, that is it.'

"'Well, take it, and burn it, or keep it.'

"'M--m. No, no, no. We will not touch it. It is fetish. You must burn it.'

"'I! Well, let it be so. I will do anything to please my good friends of Mowa.'

"'We walked to the nearest fire. I breathed a regretful farewell to my genial companion, which, during my many weary hours of night, had assisted to relieve my mind when oppressed by almost intolerable woes, and then gravely consigned the innocent Shakespeare to the flames, heaping the brush fuel over it with ceremonious care.

"'A-h-h,' breathed the poor deluded natives sighing their relief.... 'There is no trouble now.'... And something approaching to a cheer was shouted among them, which terminated the episode of the burning of Shakespeare."

[313] 'Rationality, Activity, and Faith' (Princeton Review, July 1882, pp. 64-9).

[314] J. Royce, The Religious Aspect of Philosophy (Boston, 1885). pp. 317-57.

[315] Chapter XXVII.

[316] Prof. Royce puts this well in discussing idealism and the reality of an 'external' world. "If the history of popular speculation on these topics could be written, how much of cowardice and shuffling would be found in the behavior of the natural mind before the question, 'How dost thou know of an external reality?' Instead of simply and plainly answering: 'I mean by the external world in the first place something that I accept or demand, that I posit, postulate, actively construct on the basis of sense-data,' the natural man gives us all kinds of vague compromise answers.... Where shall these endless turnings and twistings have an end?... All these lesser motives are appealed to, and the one ultimate motive is neglected. The ultimate motive with the man of every-day life is the _will to have an external world._ Whatever consciousness contains, reason will persist in spontaneously adding the thought: 'But there _shall be_ something beyond this.'... The popular assurance of an external world is the _fixed determination to make one,_ now and henceforth." (Religious Aspect of Philosophy, p. 304--the italics are my own.) This immixture of the will appears most flagrantly in the fact that although external matter is doubted commonly enough, minds external to our own are never doubted. We need them too much, are too essentially social to dispense with them. Semblances of matter may suffice to react upon, but not semblances of communing souls. A psychic solipsism is too hideous a mockery of our wants, and, so far as I know, has never been seriously entertained.--Chapters ix and x of Prof. Royce's work are on the whole the clearest account of the psychology of belief with which I am acquainted.

[317] "The leading fact in Belief, according to my view of it, is our Primitive Credulity. We begin by believing everything; whatever is, is true.... The animal born in the morning of a summer day proceeds upon the fact of daylight; assumes the perpetuity of that fact. Whatever it is disposed to do, it does without misgivings. If in the morning it began a round of operations continuing for hours, under the full benefit of daylight, it would unhesitatingly begin the same round in the evening. Its state of mind is practically one of unbounded confidence; but, as yet, it does not understand what confidence means.

"The pristine assurance is soon met by checks; a disagreeable experience leading to new insight. To be thwarted and opposed is one of our earliest and most frequent pains. It develops the sense of a distinction between free and obstructed impulses; the unconsciousness of an open way is exchanged for consciousness; we are now said properly to believe in what has never been contradicted, as we disbelieve in what has been contradicted. We believe that, after the dawn of day, there is before us a continuance of light; we do not believe that this light is to continue forever.

"Thus, the vital circumstance in belief is never to be contradicted--never to lose _prestige_. The number of repetitions counts for little in the process: we are as much convinced after ten as after fifty; we are more convinced by ten unbroken than by fifty for and one against." (Bain: The Emotions and the Will, pp. 511, 512.)

[318] _Literature._ D. Hume: Treatise on Human Nature, part iii. §§ vii-x. A. Bain: Emotions and Will, chapter on Belief (also pp. 20 ff.). J. Sully: Sensation and Intuition, essay iv. J. Mill: Analysis of Human Mind, chapter xi. Ch. Renouvier: Psychologie Rationnelle, vol. ii. pt. ii. and Esquisse d'une Classification systématique des Doctrines Philosophiques, part vi. J. H. Newman: The Grammar of Assent. J. Venn: Some Characteristics of Belief. V. Brochard: De l'Erreur, part ii. chap. vi, ix; and Revue Philosophique, xxviii. 1. E. Rabier: Psychologie, chap xxi. Appendix. Ollé Laprune: La Certitude Morale (1881). G. F. Stout: On Genesis of Cognition of Physical Reality, in 'Mind,' Jan. 1890. J. Pikler: The Psychology of the Belief in Objective Existence (London, 1890).--Mill says that we believe present sensations; and makes our belief in all other things a matter of _association_ with these. So far so good; but as he makes no mention of emotional or volitional reaction, Bain rightly charges him with treating belief as a purely intellectual state. For Bain belief is rather an incident of our active life. When a thing is such as to make us _act_ on it, then we believe it, according to Bain. "But how about past things, or remote things, upon which no reaction of ours is possible? And how about belief in things which _check_ action?" says Sully; who considers that we believe a thing only when "the idea of it has an inherent tendency to approximate in character and intensity to a sensation." It is obvious that each of these authors emphasizes a true aspect of the question. My own account has sought to be more complete, sensation, association, and active reaction all being acknowledged to be concerned. The most compendious possible formula perhaps would be that _our belief and attention_ are the same fact. For the moment, what we attend to is reality; Attention is a motor reaction; and we are so made that sensations force attention from us. On Belief and Conduct see an article by Leslie Stephen, Fortnightly Review, July 1888.

A set of facts have been recently brought to my attention which I hardly know how to treat, so I say a word about them in this foot-note. I refer to a type of experience which has frequently found a place amongst the 'Yes' answers to the 'Census of Hallucinations,' and which is generally described by those who report it as an 'impression of the presence' of someone near them, although no sensation either of sight, hearing, or touch is involved. From the way in which this experience is spoken of by those who have had it, it would appear to be an extremely definite and positive state of mind, coupled with a belief in the reality of its object quite as strong as any direct sensation ever gives. And yet _no_ sensation seems to be connected with it at all. Sometimes the person whose nearness is thus impressed is a known person, dead or living, sometimes an unknown one. His attitude and situation are often very definitely impressed, and so, sometimes (though not by way of hearing), are words which he wishes to say.

The phenomenon would seem to be due to a pure _conception_ becoming saturated with the sort of stinging urgency which ordinarily only sensations bring. But I cannot yet persuade myself that the urgency in question consists in concomitant emotional and motor impulses. The 'impression' may come quite suddenly and depart quickly; it may carry no emotional suggestions, and wake no motor consequences beyond those involved in attending to it. Altogether, the matter is somewhat paradoxical, and no conclusion can be come to until more definite data are obtained.

Perhaps the most curious case of the sort which I have received is the following. The subject of the observation, Mr. P., is an exceptionally intelligent witness, though the words of the narrative are his wife's.

"Mr. P. has all his life been the occasional subject of rather singular delusions or impressions of various kinds. If I had belief in the existence of latent or embryo faculties, other than the five senses, I should explain them on that ground. Being totally blind, his other perceptions are abnormally keen and developed, and given the existence of a rudimentary sixth sense, it would be only natural that this also should be more acute in him than in others. One of the most interesting of his experiences in this line was the frequent apparition of a corpse some years ago, which may be worth the attention of your Committee on that subject. At the time Mr. P. had a music-room in Boston on Beacon Street, where he used to do severe and protracted practice with little interruption. Now, all one season it was a very familiar occurrence with him while in the midst of work to feel a cold draft of air suddenly upon his face, with a prickling sensation at the roots of his hair, when he would turn from the piano, and a figure which he knew to be dead would come sliding under the crack of the door from without, flattening itself to squeeze through and rounding out again to the human form. It was of a middle-aged man, and drew itself along the carpet on hands and knees, but with head thrown back till it reached the sofa, upon which it stretched itself. It remained some moments, but vanished always if Mr. P. spoke or made a decided movement. The most singular point in the occurrence was its frequent repetition. He might expect it on any day between two and four o'clock, and it came always heralded by the same sudden cold shiver, and was invariably the same figure which went through the same movements. He afterwards traced the whole experience to strong tea. He was in the habit of taking cold tea, which always stimulates him, for lunch, and on giving up this practice he never saw this or any other apparition again. However, even allowing, as is doubtless true, that the event was a delusion of nerves first fatigued by overwork and then excited by this stimulant, there is one point which is still wholly inexplicable and highly interesting to me. Mr. P. has no memory whatever of sight, nor conception of it. It is impossible for him to form any idea of what we mean by light or color, consequently he has no cognizance of any object which does not reach his sense of hearing or of touch, though these are so acute as to give a contrary impression sometimes to other people. When he becomes aware of the presence of a person or an object, by means which seem mysterious to outsiders, he can always trace it naturally and legitimately to slight echoes, perceptible only to his keen ears, or to differences in atmospheric pressure, perceptible only to his acute nerves of touch; but with the apparition described, for the only time in his experience, he was aware of presence, size, and appearance, without the use of either of these mediums. The figure never produced the least sound nor came within a number of feet of his person, yet he knew that it was a man, that it moved, and in what direction, even that it wore a full beard, which, like the thick curly hair, was partially gray; also that it was dressed in the style of suit known as 'pepper and salt.' These points were all perfectly distinct and invariable each time. If asked how he perceived them, he will answer he cannot tell, he simply knew it, and so strongly and so distinctly that it is impossible to shake his opinion as to the exact details of the man's appearance. It would seem that in this delusion of the senses he really _saw_, as he has never done in the actual experiences of life, except in the first two years of childhood."

On cross-examining Mr. P., I could not make out that there was anything like visual imagination involved, although he was quite unable to describe in just what terms the false perception was carried on. It seemed to be more like an intensely definite _conception_ than anything else, a conception to which the feeling of _present reality_ was attached, but in no such shape as easily to fall under the heads laid down in my text.



CHAPTER XXII.[319]

REASONING.


We talk of man being the rational animal; and the traditional intellectualist philosophy has always made a great point of treating the brutes as wholly irrational creatures. Nevertheless, it is by no means easy to decide just what is meant by reason, or how the peculiar thinking process called reasoning differs from other thought-sequences which may lead to similar results.

Much of our thinking consists of trains of images suggested one by another, of a sort of spontaneous revery of which it seems likely enough that the higher brutes should be capable. This sort of thinking leads nevertheless to rational conclusions, both practical and theoretical. The links between the terms are either 'contiguity' or 'similarity,' and with a mixture of both these things we can hardly be very incoherent. As a rule, in this sort of irresponsible thinking, the terms which fall to be coupled together are empirical concretes, not abstractions. A sunset may call up the vessel's deck from which I saw one last summer, the companions of my voyage, my arrival into port, etc.; or it may make me think of solar myths, of Hercules' and Hector's funeral pyres, of Homer and whether he could write, of the Greek alphabet, etc. If habitual contiguities predominate, we have a prosaic mind; if rare contiguities, or similarities, have free play, we call the person fanciful, poetic, or witty. But the thought as a rule is of matters taken in their entirety. Having been thinking of one, we find later that we are thinking of another, to which we have been lifted along, we hardly know how. If an abstract quality figures in the procession, it arrests our attention but for a moment, and fades into something else; and is never very abstract. Thus, in thinking of the sun-myths, we may have a gleam of admiration at the gracefulness of the primitive human mind, or a moment of disgust at the narrowness of modern interpreters. But, in the main, we think less of qualities than of whole things, real or possible, just as we may experience them.

The upshot of it may be that we are reminded of some practical duty: we write a letter to a friend abroad, or we take down the lexicon and study our Greek lesson. Our thought is rational, and leads to a rational act, but it can hardly be called reasoning in a strict sense of the term.

There are other shorter flights of thought, single couplings of terms which suggest one another by association, which approach more to what would commonly be classed as acts of reasoning proper. Those are where a present sign suggests an unseen, distant, or future reality. Where the sign and what it suggests are both concretes which have been coupled together on previous occasions, the inference is common to both brutes and men, being really nothing more than association by contiguity. A and B, dinner-bell and dinner, have been experienced in immediate succession. Hence A no sooner falls upon the sense than B is anticipated, and steps are taken to meet it. The whole education of our domestic beasts, all the cunning added by age and experience to wild ones, and the greater part of our human knowingness consists in the ability to make a mass of inferences of this simplest sort. Our 'perceptions,' or recognitions of what objects are before us, are inferences of this kind. We feel a patch of color, and we say 'a distant house,' a whiff of odor crosses us, and we say 'a skunk,' a faint sound is heard, and we call it 'a railroad train.' Examples are needless; for such inferences of sensations not presented form the staple and tissue of our perceptive life, and our Chapter XIX was full of them, illusory or veracious. They have been called _unconscious inferences_. Certainly we are commonly unconscious that we are inferring at all. The sign and the signified melt into what seems to us the object of a single pulse of thought. _Immediate inferences_ would be a good name for these simple acts of reasoning requiring but two terms,[320] were it not that formal logic has already appropriated the expression for a more technical use.


'RECEPTS.'


In these first and simplest inferences the conclusion may follow so continuously upon the 'sign' that the latter is not discriminated or attended to as a separate object by the mind. Even now we can seldom define the optical signs which lead us to infer the shapes and distances of the objects which by their aid we so unhesitatingly perceive. The objects, too, when thus inferred, are _general_ objects. The dog crossing a scent thinks of a deer in general, or of another dog in general, not of a particular deer or dog. To these most primitive abstract objects Dr. G. J. Romanes gives the name of _recepts_ or _generic_ ideas, to distinguish them from concepts and general ideas properly so called.[321] They are not analyzed or defined, but only imagined.

"It requires but a slight analysis of our ordinary mental processes
to prove that all our simpler ideas are group-arrangements which
have been formed spontaneously or without any of that intentionally
comparing, sifting, and combining process which is required in the
higher departments of ideational activity. The comparing, sifting,
and combining is here done, as it were, _for_ the conscious agent,
not _by_ him. Recepts are received; it is only concepts that require
to be conceived.... If I am crossing a street and hear behind me a
sudden shout, I do not require to wait in order to predicate to myself
that there is probably a hansom-cab just about to run me down: a cry
of this kind, and in those circumstances, is so intimately associated
in my mind with its purpose, that the idea which it arouses need
not rise above the level of a recept; and the adaptive movements on
my part which that idea immediately prompts are performed without
any intelligent reflection. Yet, on the other hand, they are neither
reflex actions nor instinctive actions; they are what may be termed
receptual actions, or actions depending on recepts."[322]

"How far can this kind of unnamed or non-conceptional ideation extend?" Dr. Romanes asks; and answers by a variety of examples taken from the life of brutes, for which I must refer to his book. One or two of them, however, I will quote:

"Houzeau writes that while crossing a wide and arid plain in Texas,
his two dogs suffered greatly from thirst, and that between thirty
and forty times they rushed down the hollows to search for water. The
hollows were not valleys, and there were no trees in them, or any
other difference in the vegetation; and as they were absolutely dry,
there could have been no smell of damp earth. The dogs behaved as if
they knew that a dip in the ground offered them the best chance of
finding water, and Houzeau has often witnessed the same behavior in
other animals....
"Mr. Darwin writes: 'When I say to my terrier in an eager voice (and
I have made the trial many times), "Hi! hi! where is it?" she at once
takes it as a sign that something is to be hunted, and generally first
looks quickly all round, and then rushes into the nearest thicket,
to scout for any game, but finding nothing she looks up into any
neighboring tree for a squirrel. Now do not these actions clearly show
that she had in her mind a general idea, or concept, that some animal
is to be discovered and hunted?'"[323]

They certainly show this. But the idea in question is of an object _about_ which nothing farther may be articulately known. The thought of it prompts to activity, but to no theoretic consequence. Similarly in the following example:

"Water-fowl adopt a somewhat different mode of alighting upon land, or
even upon ice, from that which they adopt when alighting upon water;
and those kinds which dive from a height (such as terns and gannets)
never do so upon land or upon ice. These facts prove that the animals
have one recept answering to a solid surface, and another answering
to a fluid. Similarly a man will not dive from a height over hard
ground or over ice, nor will he jump into water in the same way as
he jumps upon dry land. In other words, like the water-fowl he has
two distinct recepts, one of which answers to solid ground, and the
other to an unresisting fluid. But unlike the water-fowl he is able
to bestow upon each of these recepts a name, and thus to raise them
both to the level of concepts. So far as the practical purposes of
locomotion are concerned, it is of course immaterial whether or not he
thus raises his recepts into concepts; but ... for many other purposes
it is of the highest importance that he is able to do this."[324]


IN REASONING, WE PICK OUT ESSENTIAL QUALITIES.


The chief of these purposes is _predication_, a theoretic function which, though it always leads eventually to some kind of action, yet tends as often as not to inhibit the immediate motor response to which the simple inferences of which we have been speaking give rise. In reasoning, A may suggest B; but B, instead of being an idea which is simply _obeyed_ by us, is an idea which suggests the distinct additional idea C. And where the train of suggestion is one of reasoning distinctively so called as contrasted with mere revery or 'associative' sequence, the ideas bear certain inward relations to each other which we must proceed to examine with some care.

The result C yielded by a true act of reasoning is apt to be a thing voluntarily _sought_, such as the means to a proposed end, the ground for an observed effect, or the effect of an assumed cause. All these results may be thought of as concrete things, but they are _not suggested immediately by other concrete things_, as in the trains of simply associative thought. They are linked to the concretes which precede them by intermediate steps, and these steps are formed by _general characters_ articulately denoted and expressly analyzed out. A thing inferred by reasoning need neither have been an habitual associate of the datum from which we infer it, nor need it be similar to it. It may be a thing entirely unknown to our previous experience, something which no simple association of concretes could ever have evoked. The great difference, in fact, between that simpler kind of rational thinking which consists in the concrete objects of past experience merely suggesting each other, and reasoning distinctively so called, is this, that whilst the empirical thinking is only reproductive, reasoning is productive. An empirical, or 'rule-of-thumb,' thinker can deduce nothing from data with whose behavior and associates in the concrete he is unfamiliar. But put a reasoner amongst a set of concrete objects which he has neither seen nor heard of before, and with a little time, if he is a good reasoner, he will make such inferences from them as will quite atone for his ignorance. Reasoning helps us out of unprecedented situations--situations for which all our common associative wisdom, all the 'education' which we share in common with the beasts, leaves us without resource.

      *       *       *       *       *

_Let us make this ability to deal with_ NOVEL _data the technical differentia of reasoning._ This will sufficiently mark it out from common associative thinking, and will immediately enable us to say just what peculiarity it contains.

_It contains analysis and abstraction._ Whereas the merely empirical thinker stares at a fact in its entirety, and remains helpless, or gets 'stuck,' if it suggests no concomitant or similar, the reasoner breaks it up and notices some one of its separate attributes. This attribute he takes to be the essential part of the whole fact before him. This attribute has properties or consequences which the fact until then was not known to have, but which, now that it is noticed to contain the attribute, it must have.

   Call the fact or concrete datum S;
       the essential attribute M;
       the attribute's property P.

Then the reasoned inference of P from S cannot be made without M's intermediation. The 'essence' M is thus that third or middle term in the reasoning which a moment ago was pronounced essential. _For his original concrete S the reasoner substitutes its abstract property, M._ What is true of M, what is coupled with M, then holds true of S, is coupled with S. As M is properly one of the _parts_ of the entire S, _reasoning may then be very well defined as the substitution of parts and their implications or consequences for wholes_. And the art of the reasoner will consist of two stages:

First, _sagacity_,[325] or the ability to discover what part, M, lies embedded in the whole S which is before him;

Second, _learning_, or the ability to recall promptly M's consequences, concomitants, or implications.[326]

If we glance at the ordinary syllogism--

   M is P;
   S is M;
   Therefore S is P

--we see that the second or minor premise, the 'subsumption' as it is sometimes called, is the one requiring the sagacity; the first or major the one requiring the fertility, or fulness of learning. Usually the learning is more apt to be ready than the sagacity, the ability to seize fresh aspects in concrete things, being rarer than the ability to learn old rules; so that, in most actual cases of reasoning, the minor premise, or the way of conceiving the subject, is the one that makes the novel step in thought. This is, to be sure, not always the case; for the fact that M carries P with it may also be unfamiliar and now formulated for the first time.

The perception that S is M is a _mode of conceiving S_. The statement that M is P is an _abstract or general proposition_. A word about both is necessary.


WHAT IS MEANT BY A MODE OF CONCEIVING.


When we conceive of S merely as M (of vermilion merely as a mercury-compound, for example), we neglect all the other attributes which it may have, and attend exclusively to this one. We mutilate the fulness of S's reality. Every reality has an infinity of aspects or properties. Even so simple a fact as a line which you trace in the air may be considered in respect to its form, its length, its direction, and its location. When we reach more complex facts, the number of ways in which we may regard them is literally endless. Vermilion is not only a mercury-compound, it is vividly red, heavy, and expensive, it comes from China, and so on, _in infinitum_. All objects are well-springs of properties, which are only little by little developed to our knowledge, and it is truly said that to know one thing thoroughly would be to know the whole universe. Mediately or immediately, that one thing is related to everything else; and to know _all_ about it, all its relations need be known. But each relation forms one of its attributes, one angle by which some one may conceive it, and while so conceiving it may ignore the rest of it. A man is such a complex fact. But out of the complexity all that an army commissary picks out as important for his purposes is his property of eating so many pounds a day; the general, of marching so many miles; the chair-maker, of having such a shape; the orator, of responding to such and such feelings; the theatre-manager, of being willing to pay just such a price, and no more, for an evening's amusement. Each of these persons singles out the particular side of the entire man which has a bearing on _his_ concerns, and not till this side is distinctly and separately conceived can the proper practical conclusions _for that reasoner_ be drawn; and when they are drawn the man's other attributes may be ignored.

All ways of conceiving a concrete fact, if they are true ways at all, are equally true ways. _There is no property_ ABSOLUTELY _essential to any one thing_. The same property which figures as the essence of a thing on one occasion becomes a very inessential feature upon another. Now that I am writing, it is essential that I conceive my paper as a surface for inscription. If I failed to do that, I should have to stop my work. But if I wished to light a fire, and no other materials were by, the essential way of conceiving the paper would be as combustible material; and I need then have no thought of any of its other destinations. It is really _all_ that it is: a combustible, a writing surface, a thin thing, a hydrocarbonaceous thing, a thing eight inches one way and ten another, a thing just one furlong east of a certain stone in my neighbor's field, an American thing, etc., etc., _ad infinitum_. Whichever one of these aspects of its being I temporarily class it under, makes me unjust to the other aspects. But as I always am classing it under one aspect or another, I am always unjust, always partial, always exclusive. My excuse is necessity--the necessity which my finite and practical nature lays upon me. My thinking is first and last and always for the sake of my doing, and I can only do one thing at a time. A God, who is supposed to drive the whole universe abreast, may also be supposed, without detriment to his activity, to see all parts of it at once and without emphasis. But were our human attention so to disperse itself we should simply stare vacantly at things at large and forfeit our opportunity of doing any particular act. Mr. Warner, in his Adirondack story, shot a bear by aiming, not at his eye or heart, but 'at him generally.' But we cannot aim 'generally' at the universe; or if we do, we miss our game. Our scope is narrow, and we must attack things piecemeal, ignoring the solid fulness in which the elements of Nature exist, and stringing one after another of them together in a serial way, to suit our little interests as they change from hour to hour. In this, the partiality of one moment is partly atoned for by the different sort of partiality of the next. To me now, writing these words, emphasis and selection seem to be the essence of the human mind. In other chapters other qualities have seemed, and will again seem, more important parts of psychology.

Men are so ingrainedly partial that, for common-sense and scholasticism (which is only common-sense grown articulate), the notion that there is no one quality genuinely, absolutely, and exclusively essential to anything is almost unthinkable. "A thing's essence makes it _what_ it is. Without an exclusive essence it would be nothing in particular, would be quite nameless, we could not say it was this rather than that. What you write on, for example,--why talk of its being combustible, rectangular, and the like, when you know that these are mere accidents, and that what it really is, and was made to be, is just _paper_ and nothing else?" The reader is pretty sure to make some such comment as this. But he is himself merely insisting on an aspect of the thing which suits his own petty purpose, that of _naming_ the thing; or else on an aspect which suits the manufacturer's purpose, that of _producing an article for which there is a vulgar demand_. Meanwhile the reality overflows these purposes at every pore. Our usual purpose with it, our commonest title for it, and the properties which this title suggests, have in reality nothing sacramental. They characterize _us_ more than they characterize the thing. But we are so stuck in our prejudices, so petrified intellectually, that to our vulgarest names, with their suggestions, we ascribe an eternal and exclusive worth. The thing must be, essentially, what the vulgarest name connotes; what less usual names connote, it can be only in an 'accidental' and relatively unreal sense.[327]

Locke undermined the fallacy. But none of his successors, so far as I know, have radically escaped it, or seen that _the only meaning of essence is teleological, and that classification and conception are purely teleological weapons of the mind_. The essence of a thing is that one of its properties which is so _important for my interests_ that in comparison with it I may neglect the rest. Amongst those other things which have this important property I class it, after this property I name it, as a thing endowed with this property I conceive it; and whilst so classing, naming, and conceiving it, all other truths about it become to me as naught.[328] The properties which are important vary from man to man and from hour to hour.[329] Hence divers appellations and conceptions for the same thing. But many objects of daily use--as paper, ink, butter, horse-car--have properties of such constant unwavering importance, and have such stereotyped names, that we end by believing that to conceive them in those ways is to conceive them in the only true way. Those are no truer ways of conceiving them than any others; they are only more important ways, more frequently serviceable ways.[330]

So much for what is implied, when the reasoner conceives of the fact S before him as a case of which the essence is to be M. One word now as to what is involved in M's having properties, consequences, or implications, and we can go back to the study of the reasoning process again.


WHAT IS INVOLVED IN GENERAL PROPOSITIONS.


M is not a concrete, or 'self-sufficient,' as Mr. Clay would say. It is an abstract character which may exist, embedded with other characters, in many concretes. Whether it be the character of being a writing surface, of being made in America or China, of being eight inches square, or of being in a certain part of space, this is always true of it. Now we might conceive of this being a world in which all such general characters were independent of each other, so that if any one of them were found in a subject S, we never could be sure what others would be found alongside of it. On one occasion there might be P with M, on another Q, and so on. In such a world there would be no _general_ sequences or coexistences, and no universal laws. Each grouping would be _sui generis_; from the experience of the past no future could be predicted; and reasoning, as we shall presently see, would be an impossibility.

But the world we live in is not one of this sort. Though many general characters seem indifferent to each other, there remain a number of them which affect constant habits of mutual concomitance or repugnance. They involve or imply each other. One of them is a sign to us that the other will be found. They hunt in couples, as it were; and such a proposition as that M is P, or includes P, or precedes or accompanies P, if it prove to be true in one instance, may very likely be true in every other instance which we meet. This is, in fact, a world in which general laws obtain, in which universal propositions _are_ true, and in which reasoning is therefore possible. Fortunately for us: for since we cannot handle things as wholes, but only by conceiving them through some general character which for the time we call their essence, it would be a great pity if the matter ended there, and if the general character, once picked out and in our possession, helped us to no farther advance. In Chapter XXVIII we shall have again to consider this harmony between our reasoning faculty and the world in which its lot is cast.[331]

To revert now to our symbolic representation of the reasoning process:

   M is P
   S is M
   ------
   S is P

M is discerned and picked out for the time being to be the essence of the concrete fact, phenomenon, or reality, S. But M in this world of ours is inevitably conjoined with P; so that P is the next thing that we may expect to find conjoined with the fact S. We may conclude or infer P, through the intermediation of the M which our sagacity began by discerning, when S came before it, to be the essence of the case.

Now note that if P have any value or importance for us, M was a very good character for our sagacity to pounce upon and abstract. If, on the contrary, P were of no importance, some other character than M would have been a better essence for us to conceive of S by. Psychologically, as a rule, P overshadows the process from the start. We are _seeking_ P, or something like P. But the bare totality of S does not yield it to our gaze; and casting about for some point in S to take hold of, which will lead us to P, we hit, if we are sagacious, upon M, because M happens to be just the character which is knit up with P. Had we wished Q instead of P, and were N a property of S conjoined with Q, we ought to have ignored M, noticed N, and conceived of S as a sort of N exclusively.

Reasoning is always for a subjective interest, to attain some particular conclusion, or to gratify some special curiosity. It not only breaks up the datum placed before it and conceives it abstractly; it must conceive it _rightly_ too; and conceiving it rightly means conceiving it by that one particular abstract character which leads to the one sort of conclusion which it is the reasoner's temporary interest to attain.[332]

The _results_ of reasoning may be hit upon by accident, The stereoscope was actually a result of reasoning; it is conceivable, however, that a man playing with pictures and mirrors might accidentally have hit upon it. Cats have been known to open doors by pulling latches, etc. But no cat, if the latch got out of order, could open the door again, unless some new accident of random fumbling taught her to associate some new total movement with the total phenomenon of the closed door. A reasoning man, however, would open the door by first analyzing the hindrance. He would ascertain what particular feature of the door was wrong. The lever, e.g., does not raise the latch sufficiently from its slot--case of insufficient elevation--raise door bodily on hinges! Or door sticks at top by friction against lintel--press it bodily down! Now it is obvious that a child or an idiot might without this reasoning learn the _rule_ for opening that particular door. I remember a clock which the maid-servant had discovered would not go unless it were supported so as to tilt slightly forwards. She had stumbled on this method after many weeks of groping. The reason of the stoppage was the friction of the pendulum-bob against the back of the clock-case, a reason which an educated man would have analyzed out in five minutes. I have a student's lamp of which the flame vibrates most unpleasantly unless the collar which bears the chimney be raised about a sixteenth of an inch. I learned the remedy after much torment by accident, and now always keep the collar up with a small wedge. But my procedure is a mere association of two totals, diseased object and remedy. One learned in pneumatics could have named the _cause_ of the disease, and thence inferred the remedy immediately. By many measurements of triangles one might find their area always equal to their height multiplied by half their base, and one might formulate an empirical law to that effect. But a reasoner saves himself all this trouble by seeing that it is the essence (_pro hac vice_) of a triangle to be the half of a parallelogram whose area is the height into the entire base. To see this he must invent additional lines; and the geometer must often draw such to get at the essential property he may require in a figure. The essence consists in some _relation of the figure to the new lines_, a relation not obvious at all until they are put in. The geometer's sagacity lies in the invention of the new lines.


THUS, THERE ARE TWO GREAT POINTS IN REASONING:


_First, an extracted character is taken as equivalent to the entire datum from which it comes; and,_

_Second, the character thus taken suggests a certain consequence more obviously than it was suggested by the total datum as it originally came._ Take them again, successively.

      *       *       *       *       *

1. Suppose I say, when offered a piece of cloth, "I won't buy that; it looks as if it would fade," meaning merely that something about it suggests the idea of fading to my mind,--my judgment, though possibly correct, is not reasoned, but purely empirical; but, if I can say that into the color there enters a certain dye which I know to be chemically unstable, and that _therefore_ the color will fade, my judgment is reasoned. The notion of the dye which is one of the parts of the cloth, is the connecting link between the latter and the notion of fading. So, again, an uneducated man will expect from past experience to see a piece of ice melt if placed near the fire, and the tip of his finger look coarse if he views it through a convex glass. In neither of these cases could the result be anticipated without full previous acquaintance with the entire phenomenon. It is not a result of reasoning.

But a man who should conceive heat as a mode of motion, and liquefaction as identical with increased motion of molecules; who should know that curved surfaces bend light-rays in special ways, and that the apparent size of anything is connected with the amount of the 'bend' of its light-rays as they enter the eye,--such a man would make the right inferences for all these objects, even though he had never in his life had any concrete experience of them; and he would do this because the ideas which we have above supposed him to possess would mediate in his mind between the phenomena he starts with and the conclusions he draws. But these ideas or reasons for his conclusions are all mere extracted portions or circumstances singled out from the mass of characters which make up the entire phenomena. The motions which form heat, the bending of the light-waves, are, it is true, excessively recondite ingredients; the hidden pendulum I spoke of above is less so; and the sticking of a door on its sill in the earlier example would hardly be so at all. But each and all agree in this, that they bear a _more evident relation_ to the conclusion than did the immediate data in their full totality.

The difficulty is, in each case, to extract from the immediate data that particular ingredient which shall have this very evident relation to the conclusion. Every phenomenon or so-called 'fact' has an infinity of aspects or properties, as we have seen, amongst which the fool, or man with little sagacity, will inevitably go astray. But no matter for this point now. The first thing is to have seen that every possible case of reasoning involves the extraction of a particular partial aspect of the phenomena thought about, and that whilst Empirical Thought simply associates phenomena in their entirety, Reasoned Thought couples them by the conscious use of this extract.

      *       *       *       *       *

2. And, now, to prove the second point: Why are the couplings, consequences, and implications of extracts more evident and obvious than those of entire phenomena? For two reasons.

First, the extracted characters are more general than the concretes, and the connections they may have are, therefore, more familiar to us, having been more often met in our experience. Think of heat as motion, and whatever is true of motion will be true of heat; but we have had a hundred experiences of motion for every one of heat. Think of the rays passing through this lens as bending towards the perpendicular, and you substitute for the comparatively unfamiliar lens the very familiar notion of a particular change in direction of a line, of which notion every day brings us countless examples.

The other reason why the relations of the extracted characters are so evident is that their properties are so _few_, compared with the properties of the whole, from which we derived them. In every concrete total the characters and their consequences are so inexhaustibly numerous that we may lose our way among them before noticing the particular consequence it behooves us to draw. But, if we are lucky enough to single out the proper character, we take in, as it were, by a single glance all its possible consequences. Thus the character of scraping the sill has very few suggestions, prominent among which is the suggestion that the scraping will cease if we raise the door; whilst the entire refractory door suggests an enormous number of notions to the mind.

Take another example. I am sitting in a railroad-car, waiting for the train to start. It is winter, and the stove fills the car with pungent smoke. The brakeman enters, and my neighbor asks him to "stop that stove smoking." He replies that it will stop entirely as soon as the car begins to move. "Why so?" asks the passenger. "It _always_ does," replies the brakeman. It is evident from this 'always' that the connection between car moving and smoke stopping was a purely empirical one in the brakeman's mind, bred of habit. But, if the passenger had been an acute reasoner, he, with no experience of what that stove always did, might have anticipated the brakeman's reply, and spared his own question. Had he singled out of all the numerous points involved in a stove's not smoking the one special point of smoke pouring freely out of the stove-pipe's mouth, he would, probably, owing to the few associations of that idea, have been immediately reminded of the law that a fluid passes more rapidly out of a pipe's mouth if another fluid be at the same time streaming over that mouth; and then the rapid draught of air over the stove-pipe's mouth, which is one of the points involved in the car's motion, would immediately have occurred to him.

Thus a couple of extracted characters, with a couple of their few and obvious connections, would have formed the reasoned link in the passenger's mind between the phenomena, smoke stopping and car moving, which were only linked as wholes in the brakeman's mind. Such examples may seem trivial, but they contain the essence of the most refined and transcendental theorizing. The reason why physics grows more deductive the more the fundamental properties it assumes are of a mathematical sort, such as molecular mass or wave-length, is that the immediate consequences of these notions are so few that we can survey them all at once, and promptly pick out those which concern us.


_Sagacity; or the Perception of the Essence._


To reason, then, we must be able to extract characters,--not _any_ characters, but the right characters for our conclusion. If we extract the wrong character, it will not lead to that conclusion. Here, then, is the difficulty: _How are characters extracted, and why does it require the advent of a genius in many cases before the fitting character is brought to light?_ Why cannot anybody reason as well as anybody else? Why does it need a Newton to notice the law of the squares, a Darwin to notice the survival of the fittest? To answer these questions we must begin a new research, and see how our insight into facts naturally grows.

All our knowledge at first is vague. When we say that a thing is vague, we mean that it has no subdivisions _ab intra_, nor precise limitations _ab extra_; but still all the forms of thought may apply to it. It may have unity, reality, externality, extent, and what not--_thinghood_, in a word, but thinghood only as a whole.[333] In this vague way, probably, does the room appear to the babe who first begins to be conscious of it as something other than his moving nurse. It has no subdivisions in his mind, unless, perhaps, the window is able to attract his separate notice. In this vague way, certainly, does every entirely new experience appear to the adult. A library, a museum, a machine-shop, are mere confused wholes to the uninstructed, but the machinist, the antiquary, and the bookworm perhaps hardly notice the whole at all, so eager are they to pounce upon the details. Familiarity has in them bred discrimination. Such vague terms as 'grass,' 'mould,' and 'meat' do not exist for the botanist or the anatomist. They know too much about grasses, moulds, and muscles. A certain person said to Charles Kingsley, who was showing him the dissection of a caterpillar, with its exquisite viscera, "Why, I thought it was nothing but skin and squash!" A layman present at a shipwreck, a battle, or a fire is helpless. Discrimination has been so little awakened in him by experience that his consciousness leaves no single point of the complex situation accented and standing out for him to begin to act upon. But the sailor, the fireman, and the general know directly at what corner to take up the business. They 'see into the situation'--that is, they analyze it--with their first glance. It is full of delicately differenced ingredients which their education has little by little brought to their consciousness, but of which the novice gains no clear idea.

How this power of analysis was brought about we saw in our chapters on Discrimination and Attention. We dissociate the elements of originally vague totals by attending to them or noticing them alternately, of course. But what determines which element we shall attend to first? There are two immediate and obvious answers: first, our practical or instinctive interests; and, second, our æsthetic interests. The dog singles out of any situation its smells, and the horse its sounds, because they may reveal facts of practical moment, and are instinctively exciting to these several creatures. The infant notices the candle-flame or the window, and ignores the rest of the room, because those objects give him a vivid pleasure. So, the country boy dissociates the blackberry, the chestnut, and the wintergreen, from the vague mass of other shrubs and trees, for their practical uses, and the savage is delighted with the beads, the bits of looking-glass, brought by an exploring vessel, and gives no heed to the features of the vessel itself, which is too much beyond his sphere. These æsthetic and practical interests, then, are the weightiest factors in making particular ingredients stand out in high relief. What they lay their accent on, that we notice; but what they are in themselves, we cannot say. We must content ourselves here with simply accepting them as irreducible ultimate factors in determining the way our knowledge grows.

Now, a creature which has few instinctive impulses, or interests, practical or æsthetic, will dissociate few characters, and will, at best, have limited reasoning powers; whilst one whose interests are very varied will reason much better. Man, by his immensely varied instincts, practical wants, and æsthetic feelings, to which every sense contributes, would, by dint of these alone, be sure to dissociate vastly more characters than any other animal; and accordingly we find that the lowest savages reason incomparably better than the highest brutes. The diverse interests lead, too, to a diversification of experiences, whose accumulation becomes a condition for the play of that _law of dissociation by varying concomitants_ of which I treated in a former chapter (see Vol I. p. 506).


_The Help given by Association by Similarity._


It is probable, also, that man's _superior association by similarity_ has much to do with those discriminations of character on which his higher flights of reasoning are based. As this latter is an important matter, and as little or nothing was said of it in the chapter on Discrimination, it behooves me to dwell a little upon it here.

What does the reader do when he wishes to see in what the precise likeness or difference of two objects lies? He transfers his attention as rapidly as possible, backwards and forwards, from one to the other. The rapid alteration in consciousness shakes out, as it were, the points of difference or agreement, which would have slumbered forever unnoticed if the consciousness of the objects compared had occurred at widely distant periods of time. What does the scientific man do who searches for the reason or law embedded in a phenomenon? He deliberately accumulates all the instances he can find which have any analogy to that phenomenon; and, by simultaneously filling his mind with them all, he frequently succeeds in detaching from the collection the peculiarity which he was unable to formulate in one alone; even though that one had been preceded in his former experience by all of those with which he now at once confronts it. These examples show that the mere general fact of having occurred at some time in one's experience, with varying concomitants, is not by itself a sufficient reason for a character to be dissociated now. We need something more; we need that the varying concomitants should in all their variety be brought into consciousness _at once_. Not till then will the character in question escape from its adhesion to each and all of them and stand alone. This will immediately be recognized by those who have read Mill's Logic as the ground of Utility in his famous 'four methods of experimental inquiry,' the methods of agreement, of difference, of residues, and of concomitant variations. Each of these gives a list of analogous instances out of the midst of which a sought-for character may roll and strike the mind.

Now it is obvious that any mind in which association by similarity is highly developed is a mind which will spontaneously form lists of instances like this. Take a present case A, with a character _m_ in it. The mind may fail at first to notice this character _m_ at all. But if A calls up C, D, E, and F,--these being phenomena which resemble A in possessing _m_, but which may not have entered for months into the experience of the animal who now experiences A, why, plainly, such association performs the part of the reader's deliberately rapid comparison referred to above, and of the systematic consideration of like cases by the scientific investigator, and may lead to the noticing of _m_ in an abstract way. Certainly this is obvious; and no conclusion is left to us but to assert that, after the few most powerful practical and æsthetic interests, our chief help towards noticing those special characters of phenomena, which, when once possessed and named, are used as reasons, class names, essences, or middle terms, _is this association by similarity._ Without it, indeed, the deliberate procedure of the scientific man would be impossible: he could never collect his analogous instances. But it operates of itself in highly-gifted minds without any deliberation, spontaneously collecting analogous instances, uniting in a moment what in nature the whole breadth of space and time keeps separate, and so permitting a perception of identical points in the midst of different circumstances, which minds governed wholly by the law of contiguity could never begin to attain.

[Illustration: FIG. 80.]

Figure 80 shows this. If _m_, in the present representation A, calls up B, C, D, and E, which are similar to A in possessing it, and calls them up in rapid succession, then _m_, being associated almost simultaneously with such varying concomitants, will 'roll out' and attract our separate notice.

If so much is clear to the reader, he will be willing to admit that the mind _in which this mode of association most prevails_ will, from its better opportunity of extricating characters, be the one most prone to reasoned thinking; whilst, on the other hand, a mind in which we do not detect reasoned thinking will probably be one in which association by contiguity holds almost exclusive sway.

Geniuses are, by common consent, considered to differ from ordinary minds by an unusual development of association by similarity. One of Professor Bain's best strokes of work is the exhibition of this truth.[334] It applies to geniuses in the line of reasoning as well as in other lines. And as the genius is to the vulgarian, so the vulgar human mind is to the intelligence of a brute. Compared with men, it is probable that brutes neither attend to abstract characters, nor have associations by similarity. Their thoughts probably pass from one concrete object to its habitual concrete successor far more uniformly than is the case with us. In other words, their associations of ideas are almost exclusively by contiguity. It will clear up still farther our understanding of the reasoning process, if we devote a few pages to


THE INTELLECTUAL CONTRAST BETWEEN BRUTE AND MAN.


I will first try to show, by taking the best stories I can find of animal sagacity, that the mental process involved may as a rule be perfectly accounted for by mere contiguous association, based on experience. Mr. Darwin, in his 'Descent of Man,' instances the Arctic dogs, described by Dr. Hayes, who scatter, when drawing a sledge, as soon as the ice begins to crack. This might be called by some an exercise of reason. The test would be, Would the most intelligent Eskimo dogs that ever lived act so when placed upon ice for the first time together? A band of men from the tropics might do so easily. Recognizing cracking to be a sign of breaking, and seizing immediately the partial character that the point of rupture is the point of greatest strain, and that the massing of weight at a given point concentrates there the strain, a Hindoo might quickly infer that scattering would stop the cracking, and, by crying out to his comrades to disperse, save the party from immersion. But in the dog's case we need only suppose that they have individually experienced wet skins after cracking, that they have often noticed cracking to begin when they were huddled together, and that they have observed it to cease when they scattered. Naturally, therefore, the sound would redintegrate all these former experiences, including that of scattering, which latter they would promptly renew. It would be a case of immediate suggestion or of that 'Logic of Recepts' as Mr. Romanes calls it, of which we spoke above on p. 327.

A friend of the writer gave as a proof of the almost human intelligence of his dog that he took him one day down to his boat on the shore, but found the boat full of dirt and water. He remembered that the sponge was up at the house, a third of a mile distant; but, disliking to go back himself, he made various gestures of wiping out the boat and so forth, saying to his terrier, "Sponge, sponge; go fetch the sponge." But he had little expectation of a result, since the dog had never received the slightest training with the boat or the sponge. Nevertheless, off he trotted to the house, and, to his owner's great surprise and admiration, brought the sponge in his jaws. Sagacious as this was, it required nothing but ordinary contiguous association of ideas. The terrier was only exceptional in the minuteness of his spontaneous observation. Most terriers would have taken no interest in the boat-cleaning operation, nor noticed what the sponge was for. This terrier, in having picked those details out of the crude mass of his boat-experience distinctly enough to be reminded of them, was truly enough ahead of his peers on the line which leads to human reason. But his act was not yet an act of reasoning proper. It might fairly have been called so if, unable to find the sponge at the house, he had brought back a dipper or a mop instead. Such a substitution would have shown that, embedded in the very different appearances of these articles, he had been able to discriminate the identical partial attribute of capacity to take up water, and had reflected, "For the present purpose they are identical." This, which the dog did not do, any man but the very stupidest could not fail to do.

If the reader will take the trouble to analyze the best dog and elephant stories he knows, he will find that, in most cases, this simple contiguous calling up of one whole by another is quite sufficient to explain the phenomena. Sometimes, it is true, we have to suppose the recognition of a property or character as such, but it is then always a character which the peculiar practical interests of the animal may have singled out. A dog, noticing his master's hat on its peg, may possibly infer that he has not gone out. Intelligent dogs recognize by the tone of the master's voice whether the latter is angry or not. A dog will perceive whether you have kicked him by accident or by design, and behave accordingly. The character inferred by him, the particular mental state in you, however it be represented in his mind--it is represented probably by a 'recept' (p. 327) or set of practical tendencies, rather than by a definite concept or idea--is still a partial character extracted from the totality of your phenomenal being, and is his reason for crouching and skulking, or playing with you. Dogs, moreover, seem to have the feeling of the value of their master's personal property, or at least a particular _interest_ in objects which their master uses. A dog left with his master's coat will defend it, though never taught to do so. I know of a dog accustomed to swim after sticks in the water, but who always refused to dive for stones. Nevertheless, when a fish-basket, which he had never been trained to carry, but merely knew as his master's, fell over, he immediately dived after it and brought it up. Dogs thus discern, at any rate so far as to be able to act, this partial character of _being valuable_, which lies hidden in certain things.[335] Stories are told of dogs carrying coppers to pastry-cooks to get buns, and it is said that a certain dog, if he gave two coppers, would never leave without two buns. This was probably mere contiguous association, but it is _possible_ that the animal noticed the character of duality, and identified it as the same in the coin and the cake. If so, it is the maximum of canine abstract thinking. Another story told to the writer is this: a dog was sent to a lumber-camp to fetch a wedge, with which he was known to be acquainted. After half an hour, not returning, he was sought and found biting and tugging at the handle of an axe which was driven deeply into a stump. The wedge could not be found. The teller of the story thought that the dog must have had a clear perception of the common character of serving to split which was involved in both the instruments, and, from their identity in this respect, inferred their identity for the purposes required.

It cannot be denied that this interpretation is a possible one, but it seems to me far to transcend the limits of ordinary canine abstraction. The property in question was not one which had direct personal interest for the dog, such as that of belonging to his master is in the case of the coat or the basket. If the dog in the sponge story had returned to the boat with a dipper it would have been no more remarkable. It seems more probable, therefore, that this wood-cutter's dog had also been accustomed to carry the axe, and now, excited by the vain hunt for the wedge, had discharged his carrying powers upon the former instrument in a sort of confusion--just as a man may pick up a sieve to carry water in, in the excitement of putting out a fire.[336]

Thus, then, the characters extracted by animals are very few, and always related to their immediate interests or emotions. That dissociation by varying concomitants, which in man is based so largely on association by similarity, hardly seems to take place at all in the mind of brutes. One total thought suggests to them another total thought, and they find themselves acting with propriety, they know not why. The great, the fundamental, defect of their minds seems to be the inability of their groups of ideas to break across in unaccustomed places. They are enslaved to routine, to cut-and-dried thinking; and if the most prosaic of human beings could be transported into his dog's mind, he would be appalled at the utter absence of fancy which reigns there.[337] Thoughts will not be found to call up their similars, but only their habitual successors. Sunsets will not suggest heroes' deaths, but supper-time. This is why man is the only metaphysical animal. To wonder why the universe should be as it is presupposes the notion of its being different, and a brute, which never reduces the actual to fluidity by breaking up its literal sequences in his imagination, can never form such a notion. He takes the world simply for granted, and never wonders at it at all.

Professor Strümpell quotes a dog-story which is probably a type of many others. The feat performed looks like abstract reasoning; but an acquaintance with all the circumstances shows it to have been a random trick learned by habit. The story is as follows:

"I have two dogs, a small, long-legged pet dog and a rather large
watch-dog. Immediately beyond the house-court is the garden, into
which one enters through a low lattice-gate which is closed by a
latch on the yard-side. This latch is opened by lifting it. Besides
this, moreover, the gate is fastened on the garden-side by a string
nailed to the gate-post. Here, as often as one wished, could the
following sight be observed. If the little dog was shut in the
garden and he wished to get out, he placed himself before the gate
and barked. Immediately the large dog in the court would hasten to
him and raise the latch with his nose while the little dog on the
garden-side leaped up and, catching the string in his teeth, bit it
through; whereupon the big one wedged his snout between the gate and
the post, pushed the gate open, and the little dog slipped through.
Certainly reasoning seems here to prevail. In face of it, however,
and although the dogs arrived of themselves, and without human aid,
at their solution of the gate question, I am able to point out that
the complete action was pieced together out of accidental experiences
which the dogs followed, I might say, unconsciously. While the large
dog was young, he was allowed, like the little one, to go into the
garden, and therefore the gate was usually not latched, but simply
closed. Now if he saw anyone go in, he would follow by thrusting his
snout between gate and post, and so pushing the gate open. When he was
grown I forbade his being taken in, and had the gate kept latched. But
he naturally still tried to follow when anyone entered and tried in
the old fashion to open it, which he could no longer do. Now it fell
out that once, while making the attempt, he raised his nose higher
than usual and hit the latch from below so as to lift it off its hook,
and the gate unclosed. From thenceforth he made the same movement of
the head when trying to open it, and, of course, with the same result.
He now knew how to open the gate when it was latched.
"The little dog had been the large one's teacher in many things,
especially in the chasing of cats and the catching of mice and moles;
so when the little one was heard barking eagerly, the other always
hastened to him. If the barking came from the garden, he opened the
gate to get inside. But meanwhile the little dog, who wanted to get
out the moment the gate opened, slipped out between the big one's
legs, and so the appearance of his having come with the intention of
letting him out arose. And that it was simply an appearance transpired
from the fact that when the little dog did not succeed at once in
getting out, the large one ran in and nosed about the garden, plainly
showing that he had expected to find something there. In order to
stop this opening of the gate I fastened a string on the garden-side
which, tightly drawn, held the gate firm against the post, so that if
the yard dog raised the latch and let go, it would every time fall
back on to the hook. And this device was successful for quite a time,
until it happened one day that on my return from a walk upon which the
little dog had accompanied me I crossed the garden, and in passing
through the gate the dog remained behind, and refused to come to my
whistle. As it was beginning to rain, and I knew how he disliked to
get wet, I closed the gate in order to punish him in this manner. But
I had hardly readied the house ere he was before the gate, whining and
crying most piteously, for the rain was falling faster and faster.
The big dog, to whom the rain was a matter of perfect indifference,
was instantly on hand and tried his utmost to open the gate, but
naturally without success. Almost in despair the little dog bit at the
gate, at the same time springing into the air in the attempt to jump
over it, when he chanced to catch the string in his teeth; it broke,
and the gate flew open. Now he knew the secret and thenceforth bit the
string whenever he wished to get out, so that I was obliged to change
it.
"That the big dog in raising the latch did not in the least _know_
that the latch closed the gate, that the raising of the same opened
it, but that he merely repeated the automatic blow with his snout
which had once had such happy consequences, transpires from the
following: the gate leading to the barn is fastened with a latch
precisely like the one on the garden-gate, only placed a little
higher, still easily within the dog's reach. Here, too, occasionally
the little dog is confined, and when he barks the big one makes every
possible effort to open the gate, but it has never occurred to him
to push the latch up. The brute cannot draw conclusions, that is, he
cannot think."[338]

Other classical _differentiæ_ of man besides that of being the only reasoning animal, also seem consequences of his unrivalled powers of similar association. He has, e.g., been called 'the laughing animal.' But humor has often been defined as the recognition of identities in things different. When the man in Coriolanus says of that hero that "there is no more mercy in him than there is milk in a male tiger," both the invention of the phrase and its enjoyment by the hearer depend on a peculiarly perplexing power to associate ideas by similarity.

Man is known again as 'the talking animal'; and language is assuredly a capital distinction between man and brute. But it may readily be shown how this distinction merely flows from those we have pointed out, easy dissociation of a representation into its ingredients, and association by similarity.

Language is a system of _signs_, different from the things signified, but able to suggest them.

No doubt brutes have a number of such signs. When a dog yelps in front of a door, and his master, understanding his desire, opens it, the dog may, after a certain number of repetitions, get to repeat in cold blood a yelp which was at first the involuntary interjectional expression of strong emotion. The same dog may be taught to 'beg' for food, and afterwards come to do so deliberately when hungry. The dog also learns to understand the signs of men, and the word 'rat' uttered to a terrier suggests exciting thoughts of the rat-hunt. If the dog had the varied impulse to vocal utterance which some other animals have, he would probably repeat the word 'rat' whenever he spontaneously happened to think of a rat-hunt--he no doubt does have it as an auditory image, just as a parrot calls out different words spontaneously from its repertory, and having learned the name of a given dog will utter it on the sight of a different dog. In each of these separate cases the particular sign _may_ be consciously noticed by the animal, as distinct from the particular thing signified, and will thus, so far as it goes, be a true manifestation of language. But when we come to man we find a great difference. _He has a deliberate intention to apply a sign to everything._ The linguistic impulse is with him generalized and systematic. For things hitherto unnoticed or unfelt, he _desires_ a sign before he has one. Even though the dog should possess his 'yelp' for this thing, his 'beg' for that, and his auditory image 'rat' for a third thing, the matter with him rests there. If a fourth thing interests him for which no sign happens already to have been learned, he remains tranquilly without it and goes no further. But the man _postulates_ it, its absence irritates him, and he ends by inventing it. _This_ GENERAL PURPOSE _constitutes, I take it, the peculiarity of human speech, and explains its prodigious development._

How, then, does the general purpose arise? It arises as soon as the notion of a _sign as such_, apart from any particular import, is born; and this notion is born by dissociation from the outstanding portions of a number of concrete cases of signification. The 'yelp,' the 'beg,' the 'rat,' differ as to their several imports and natures. They agree only in so far as they have the same _use_--to _be signs_, to stand for something more important than themselves. The dog whom this similarity could strike would have grasped the sign _per se_ as such, and would probably thereupon become a general sign-maker, or speaker in the human sense. But how can the similarity strike him? Not without the juxtaposition of the similars (in virtue of the law we have laid down (Vol. I. p. 506), that in order to be segregated an experience must be repeated with varying concomitants)--not unless the 'yelp' of the dog at the moment it occurs _recalls_ to him his 'beg,' by the delicate bond of their subtle similarity of use--not till then can this thought flash through his mind: "Why, yelp and beg, in spite of all their unlikeness, are yet alike in this: that they are actions, signs, which lead to important boons. Other boons, _any_ boons, may then be got by other signs!" This reflection made, the gulf is passed. Animals probably never make it, because the bond of similarity is not delicate enough. Each sign is drowned in _its_ import, and never awakens other signs and other imports in juxtaposition. The rat-hunt idea is too absorbingly interesting in itself to be interrupted by anything so uncontiguous to it as the idea of the 'beg for food,' or of 'the door-open yelp,' nor in their turn do these awaken the rat-hunt idea.

In the human child, however, these ruptures of contiguous association are very soon made; far off cases of sign-using arise when we make a sign now; and soon language is launched. The child in each case makes the discovery for himself. No one can help him except by furnishing him with the conditions. But as he is constituted, the conditions will sooner or later shoot together into the result.[339]

The exceedingly interesting account which Dr. Howe gives of the education of his various blind-deaf mutes illustrates this point admirably. He began to teach Laura Bridgman by gumming raised letters on various familiar articles. The child was taught by mere contiguity to pick out a certain number of particular articles when made to feel the letters. But this was merely a collection of particular signs, out of the mass of which the general purpose of _signification_ had not yet been extracted by the child's mind. Dr. Howe compares his situation at this moment to that of one lowering a line to the bottom of the deep sea in which Laura's soul lay, and waiting until she should spontaneously take hold of it and be raised into the light. The moment came, 'accompanied by a radiant flash of intelligence and glow of joy'; she seemed suddenly to become aware of the general purpose imbedded in the different details of all these signs, and from that moment her education went on with extreme rapidity.

Another of the great capacities in which man has been said to differ fundamentally from the animal is that of possessing self-consciousness or reflective knowledge of himself as a thinker. But this capacity also flows from our criterion, for (without going into the matter very deeply) we may say that the brute never reflects on himself as a thinker, because he has never clearly dissociated, in the full concrete act of thought, the element of the thing thought of and the operation by which he thinks it. They remain always fused, conglomerated--just as the interjectional vocal sign of the brute almost invariably merges in his mind with the thing signified, and is not independently attended to _in se_.[340]

Now, the dissociation of these two elements probably occurs first in the child's mind on the occasion of some error or false expectation which would make him experience the shock of difference between merely imagining a thing and getting it. The thought experienced once with the concomitant reality, and then without it or with opposite concomitants, reminds the child of other cases in which the same provoking phenomenon occurred. Thus the general ingredient of error may be dissociated and noticed _per se_, and from the notion of his error or wrong thought to that of his thought in general the transition is easy. The brute, no doubt, has plenty of instances of error and disappointment in his life, but the similar shock is in him most likely always swallowed up in the accidents of the actual case. An expectation disappointed may breed dubiety as to the realization of that particular thing when the dog next expects it. But that disappointment, that dubiety, while they are present in the mind, will _not_ call up other cases, in which the material details were different, but this feature of possible error was the same. The brute will, therefore, stop short of dissociating the general notion of error _per se_, and _a fortiori_ will never attain the conception of Thought itself as such.

      *       *       *       *       *

We may then, we think, consider it proven that _the most elementary single difference between the human mind and that of brutes lies in this deficiency on the brute's part to associate ideas by similarity_--characters, the abstraction of which depends on this sort of association, must in the brute always remain drowned, swamped in the total phenomenon which they help constitute, and never used to reason from. If a character stands out alone, it is always some obvious sensible quality like a sound or a smell which is instinctively exciting and lies in the line of the animal's propensities; or it is some obvious sign which experience has habitually coupled with a consequence, such as, for the dog, the sight of his master's hat on and the master's going out.


DIFFERENT ORDERS OF HUMAN GENIUS.


But, now, since nature never makes a jump, it is evident that we should find the lowest men occupying in this respect an intermediate position between the brutes and the highest men. And so we do. Beyond the analogies which their own minds suggest by breaking up the literal sequence of their experience, there is a whole world of analogies which they can appreciate when imparted to them by their betters, but which they could never excogitate alone. This answers the question why Darwin and Newton had to be waited for so long. The flash of similarity between an apple and the moon, between the rivalry for food in nature and the rivalry for man's selection, was too recondite to have occurred to any but exceptional minds. _Genius, then,_ as has been already said, _is identical with the possession of similar association to an extreme degree._ Professor Bain says: "This I count the leading fact of genius. I consider it quite impossible to afford any explanation of intellectual originality except on the supposition of unusual energy on this point." Alike in the arts, in literature, in practical affairs, and in science, association by similarity is the prime condition of success.

But as, according to our view, there are two stages in reasoned thought, one where similarity merely _operates_ to call up cognate thoughts, and another farther stage, where the bond of identity between the cognate thoughts is _noticed_; so _minds of genius may be divided into two main sorts, those who notice the bond and those who merely obey it._ The first are the abstract reasoners, properly so called, the men of science, and philosophers--the analysts, in a word; the latter are the poets, the critics--the artists, in a word, the men of intuitions. These judge rightly, classify cases, characterize them by the most striking analogic epithets, but go no further. At first sight it might seem that the analytic mind represented simply a higher intellectual stage, and that the intuitive mind represented an arrested stage of intellectual development; but the difference is not so simple as this. Professor Bain has said that a man's advance to the scientific stage (the stage of noticing and abstracting the bond of similarity) may often be due to an _absence_ of certain emotional sensibilities. The sense of color, he says, may no less determine a mind away from science than it determines it toward painting. There must be a penury in one's interest in the details of particular forms in order to permit the forces of the intellect to be concentrated on what is common to many forms.[341] In other words, supposing a mind fertile in the suggestion of analogies, but, at the same time, keenly interested in the particulars of each suggested image, that mind would be far less apt to single out the particular character which called up the analogy than one whose interests were less generally lively. A certain richness of the æsthetic nature may, therefore, easily keep one in the intuitive stage. All the poets are examples of this. Take Homer:

"Ulysses, too, spied round the house to see if any man were still
alive and hiding, trying to get away from gloomy death. He found them
all fallen in the blood and dirt, and in such number as the fish which
the fishermen to the low shore, out of the foaming sea, drag with
their meshy nets. These all, sick for the ocean water, are strewn
around the sands, while the blazing sun takes their life from them. So
there the suitors lay strewn round on one another." Or again:
"And as when a Mæonian or a Carian woman stains ivory with purple to
be a cheek-piece for horses, and it is kept in the chamber, and many
horsemen have prayed to bear it off; but it is kept a treasure for a
king, both a trapping for his horse and a glory to the driver--in such
wise were thy stout thighs, Menelaos, and legs and fair ankles stained
with blood."[342]

A man in whom all the accidents of an analogy rise up as vividly as this, may be excused for not attending to the ground of the analogy. But he need not on that account be deemed intellectually the inferior of a man of drier mind, in whom the ground is not as liable to be eclipsed by the general splendor. Barely are both sorts of intellect, the splendid and the analytic, found in conjunction. Plato among philosophers, and M. Taine, who cannot quote a child's saying without describing the '_voix chantante, étonnée, heureuse_' in which it is uttered, are only exceptions whose strangeness proves the rule.

An often-quoted writer has said that Shakespeare possessed more _intellectual power_ than any one else that ever lived. If by this he meant the power to pass from given premises to right or congruous conclusions, it is no doubt true. The abrupt transitions in Shakespeare's thought astonish the reader by their unexpectedness no less than they delight him by their fitness. Why, for instance, does the death of Othello so stir the spectator's blood and leave him with a sense of reconcilement? Shakespeare himself could very likely not say why; for his invention, though rational, was not ratiocinative. Wishing the curtain to fall upon a reinstated Othello, that speech about the turbaned Turk suddenly simply flashed across him as the right end of all that went before. The dry critic who comes after can, however, point out the subtle bonds of identity that guided Shakespeare's pen through that speech to the death of the Moor. Othello is sunk in ignominy, lapsed from his height at the beginning of the play. What better way to rescue him at last from this abasement than to make him for an instant identify himself in memory with the old Othello of better days, and then execute justice on his present disowned body, as he used then to smite all enemies of the State? But Shakespeare, whose mind supplied these means, could probably not have told why they were so effective.

But though this is true, and though it would be absurd in an absolute way to say that a given analytic mind was superior to any intuitional one, yet it is none the less true that the former _represents_ the higher stage. Men, taken historically, reason by analogy long before they have learned to reason by abstract characters. Association by similarity and true reasoning may have identical results. If a philosopher wishes to prove to you why you should do a certain thing, he may do so by using abstract considerations exclusively; a savage will prove the same by reminding you of a similar case in which you notoriously do as he now proposes, and this with no ability to state the _point_ in which the cases are similar. In all primitive literature, in all savage oratory, we find persuasion carried on exclusively by parables and similes, and travellers in savage countries readily adopt the native custom. Take, for example, Dr. Livingstone's argument with the negro conjuror. The missionary was trying to dissuade the savage from his fetichistic ways of invoking rain. "You see," said he, "that, after all your operations, sometimes it rains and sometimes it does not, exactly as when you have not operated at all." "But," replied the sorcerer, "it is just the same with you doctors; you give your remedies, and sometimes the patient gets well and sometimes he dies, just as when you do nothing at all." To that the pious missionary replied: "The doctor does his duty, after which God performs the cure if it pleases Him." "Well," rejoined the savage, "it is just so with me. I do what is necessary to procure rain, after which God sends it or withholds it according to His pleasure."[343]

This is the stage in which proverbial philosophy reigns supreme. "An empty sack can't stand straight" will stand for the reason why a man with debts may lose his honesty; and "a bird in the hand is worth two in the bush" will serve to back up one's exhortations to prudence. Or we answer the question: "Why is snow white?" by saying, "For the same reason that soap-suds or whipped eggs are white"--in other words, instead of giving the _reason_ for a fact, we give another _example_ of the same fact. This offering a similar instance, instead of a reason, has often been criticised as one of the forms of logical depravity in men. But manifestly it is not a perverse act of thought, but only an incomplete one. Furnishing parallel cases is the necessary first step towards abstracting the reason imbedded in them all.

As it is with reasons, so it is with words. The first words are probably always names of entire things and entire actions, of extensive coherent groups. A new experience in the primitive man can only be talked about by him in terms of the old experiences which have received names. It reminds him of certain ones from among them, but the _points_ in which it agrees with them are neither named nor dissociated. Pure similarity must work before the abstraction can work which is based upon it. The first adjectives will therefore probably be total nouns embodying the striking character. The primeval man will say, not 'the bread is hard,' but 'the bread is stone'; not 'the face is round,' but 'the face is moon'; not 'the fruit is sweet,' but 'the fruit is sugar-cane.' The first words are thus neither particular nor general, but _vaguely_ concrete; just as we speak of an 'oval' face, a 'velvet' skin, or an 'iron' will, without meaning to connote any other attributes of the adjective-noun than those in which it _does_ resemble the noun it is used to qualify. After a while certain of these adjectively-used nouns come only to signify the particular quality for whose sake they are oftenest used; the _entire thing_ which they originally meant receives another name, and they become true abstract and general terms. Oval, for example, with us suggests _only_ shape. The first abstract qualities thus formed are, no doubt, qualities of one and the same sense found in different objects--as big, sweet; next analogies between different senses, as 'sharp' of taste, 'high' of sound, etc.; then analogies of motor combinations, or form of relation, as simple, confused, difficult, reciprocal, relative, spontaneous, etc. The extreme degree of subtlety in analogy is reached in such cases as when we say certain English art critics' writing reminds us of a close room in which pastilles have been burning, or that the mind of certain Frenchmen is like old Roquefort cheese. Here language utterly fails to hit upon the basis of resemblance.

Over immense departments of our thought we are still, all of us, in the savage state. Similarity operates in us, but abstraction has not taken place. We know what the present case is like, we know what it reminds us of, we have an intuition of the right course to take, if it be a practical matter. But analytic thought has made no tracks, and we cannot justify ourselves to others. In ethical, psychological, and æsthetic matters, to give a clear reason for one's judgment is universally recognized as a mark of rare genius. The helplessness of uneducated people to account for their likes and dislikes is often ludicrous. Ask the first Irish girl why she likes this country better or worse than her home, and see how much she can tell you. But if you ask your most educated friend why he prefers Titian to Paul Veronese, you will hardly get more of a reply; and you will probably get absolutely none if you inquire why Beethoven reminds him of Michael Angelo, or how it comes that a bare figure with unduly flexed joints, by the latter, can so suggest the moral tragedy of life. His thought obeys a _nexus_, but cannot name it. And so it is with all those judgments of _experts_, which even though unmotived are so valuable. Saturated with experience of a particular class of materials, an expert intuitively feels whether a newly-reported fact is probable or not, whether a proposed hypothesis is worthless or the reverse. He instinctively knows that, in a novel case, this and not that will be the promising course of action. The well-known story of the old judge advising the new one never to give reasons for his decisions, "the decisions will probably be right, the reasons will surely be wrong," illustrates this. The doctor will feel that the patient is doomed, the dentist will have a premonition that the tooth will break, though neither can articulate a reason for his foreboding. The reason lies imbedded, but not yet laid bare, in all the countless previous cases dimly suggested by the actual one, all calling up the same conclusion, which the adept thus finds himself swept on to, he knows not how or why.

      *       *       *       *       *

_A physiological conclusion remains to be drawn._ If the principles laid down in Chapter XIV are true, then it follows that the great cerebral difference between habitual and reasoned thinking must be this: that in the former an entire system of cells vibrating at any one moment discharges in its totality into another entire system, and that the order of the discharges tends to be a constant one in time; whilst in the latter a part of the prior system still keeps vibrating in the midst of the subsequent system, and the order--which part this shall be, and what shall be its concomitants in the subsequent system--has little tendency to fixedness in time. This physical selection, so to call it, of one part to vibrate persistently whilst the others rise and subside, we found, in the chapter in question, to be the basis of similar association. (See especially Vol. I. pp. 578-81.) It would seem to be but a minor degree of that still more urgent and importunate localized vibration which we can easiest conceive to underlie the mental fact of interest, attention, or dissociation. In terms of the brain-process, then, all these mental facts resolve themselves into a single peculiarity: that of indeterminateness of connection between the different tracts, and tendency of action to focalize itself, so to speak, in small localities which vary infinitely at different times, and from which irradiation may proceed in countless shifting ways. (Compare figure 80, p. 347.) To discover, or (what more befits the present stage of nerve-physiology) to adumbrate by some possible guess, on what chemical or molecular-mechanical fact this instable equilibrium of the human brain may depend, should be the next task of the physiologist who ponders over the passage from brute to man. Whatever the physical peculiarity in question may be, _it_ is the cause why a man, whose brain has it, reasons so much, whilst his horse, whose brain lacks it, reasons so little. We can but bequeath the problem to abler hands than our own.

But, meanwhile, this mode of stating the matter suggests a couple of other inferences. The first is brief. If _focalization_ of brain-activity be the fundamental fact of reasonable thought, we see why intense interest or concentrated passion makes us think so much more truly and profoundly. The persistent _focalization_ of motion in certain tracts is the cerebral fact corresponding to the persistent domination in consciousness of the important feature of the subject. When not 'focalized,' we are scatter-brained; but when thoroughly impassioned, we never wander from the point. None but congruous and relevant images arise. When roused by indignation or moral enthusiasm, how trenchant are our reflections, how smiting are our words! The whole network of petty scruples and by-considerations which, at ordinary languid times, surrounded the matter like a cobweb, holding back our thought, as Gulliver was pinned to the earth by the myriad Lilliputian threads, are dashed through at a blow, and the subject stands with its essential and vital lines revealed.

      *       *       *       *       *

The last point is relative to the theory that what was acquired habit in the ancestor may become congenital tendency in the offspring. So vast a superstructure is raised upon this principle that the paucity of empirical evidence for it has alike been matter of regret to its adherents, and of triumph to its opponents. In Chapter XXVIII we shall see what we may call the whole beggarly array of proof. In the human race, where our opportunities for observation are the most complete, we seem to have no evidence whatever which would support the hypothesis, unless it possibly be the law that city-bred children are more apt to be near-sighted than country children. In the mental world we certainly do not observe that the children of great travellers get their geography lessons with unusual ease, or that a baby whose ancestors have spoken German for thirty generations will, on that account, learn Italian any the less easily from its Italian nurse. But if the considerations we have been led to are true, they explain perfectly well why this law _should not_ be verified in the human race, and why, therefore, in looking for evidence on the subject, we should confine ourselves exclusively to lower animals. In them fixed habit is the essential and characteristic law of nervous action. The brain grows to the exact modes in which it has been exercised, and the inheritance of these modes--then called instincts--would have in it nothing surprising. But in man the negation of all fixed modes is the essential characteristic. He owes his whole pre-eminence as a reasoner, his whole human quality of intellect, we may say, to the facility with which a given mode of thought in him may suddenly be broken up into elements, which recombine anew. Only at the price of inheriting no settled instinctive tendencies is he able to settle every novel case by the fresh discovery by his reason of novel principles. He is, _par excellence_, the _educable_ animal. If, then, the law that habits are inherited were found exemplified in him, he would, in so far forth, fall short of his human perfections; and, when we survey the human races, we actually do find that those which are most instinctive at the outset are those which, on the whole, are least educated in the end. An untutored Italian is, to a great extent, a man of the world; he has instinctive perceptions, tendencies to behavior, reactions, in a word, upon his environment, which the untutored German wholly lacks. If the latter be not drilled, he is apt to be a thoroughly loutish personage; but, on the other hand, the mere absence in his brain of definite innate tendencies enables him to advance by the development, through education, of his purely reasoned thinking, into complex regions of consciousness that the Italian may probably never approach.

We observe an identical difference between men as a whole and women as a whole. A young woman of twenty reacts with intuitive promptitude and security in all the usual circumstances in which she may be placed.[344] Her likes and dislikes are formed; her opinions, to a great extent, the same that they will be through life. Her character is, in fact, finished in its essentials. How inferior to her is a boy of twenty in all these respects! His character is still gelatinous, uncertain what shape to assume, 'trying it on' in every direction. Feeling his power, yet ignorant of the manner in which he shall express it, he is, when compared with his sister, a being of no definite contour. But this absence of prompt tendency in his brain to set into particular modes is the very condition which insures that it shall ultimately become so much more efficient than the woman's. The very lack of preappointed trains of thought is the ground on which general principles and heads of classification grow up; and the masculine brain deals with new and complex matter indirectly by means of these, in a manner which the feminine method of direct intuition, admirably and rapidly as it performs within its limits, can vainly hope to cope with.

      *       *       *       *       *

In looking back over the subject of reasoning, one feels how intimately connected it is with conception; and one realizes more than ever the deep reach of that principle of selection on which so much stress was laid towards the close of Chapter IX. As the art of reading (after a certain stage in one's education) is the art of skipping, so the art of being wise is the art of knowing what to overlook. The first effect on the mind of growing cultivated is that processes once multiple get to be performed by a single act. Lazarus has called this the progressive 'condensation' of thought. But in the psychological sense it is less a condensation than a loss, a genuine dropping out and throwing overboard of conscious content. Steps really sink from sight. An advanced thinker sees the relations of his topics in such masses and so instantaneously that when he comes to explain to younger minds it is often hard to say which grows the more perplexed, he or the pupil. In every university there are admirable investigators who are notoriously bad lecturers. The reason is that they never spontaneously see the subject in the minute articulate way in which the student needs to have it offered to his slow reception. They grope for the links, but the links do not come. Bowditch, who translated and annotated Laplace's Mécanique Céleste, said that whenever his author prefaced a proposition by the words 'it is evident,' he knew that many hours of hard study lay before him.

When two minds of a high order, interested in kindred subjects, come together, their conversation is chiefly remarkable for the summariness of its allusions and the rapidity of its transitions. Before one of them is half through a sentence the other knows his meaning and replies. Such genial play with such massive materials, such an easy flashing of light over far perspectives, such careless indifference to the dust and apparatus that ordinarily surround the subject and seem to pertain to its essence, make these conversations seem true feasts for gods to a listener who is educated enough to follow them at all. His mental lungs breathe more deeply, in an atmosphere more broad and vast than is their wont. On the other hand, the excessive explicitness and short-windedness of an ordinary man are as wonderful as they are tedious to the man of genius. But we need not go as far as the ways of genius. Ordinary social intercourse will do. There the charm of conversation is in direct proportion to the possibility of abridgment and elision, and in inverse ratio to the need of explicit statement. With old friends a word stands for a whole story or set of opinions. With new-comers everything must be gone over in detail. Some persons have a real mania for completeness, they must express every step. They are the most intolerable of companions, and although their mental energy may in its way be great, they always strike us as weak and second-rate. In short, the essence of plebeianism, that which separates vulgarity from aristocracy, is perhaps less a defect than an excess, the constant need to animadvert upon matters which for the aristocratic temperament do not exist. To ignore, to disdain to consider, to overlook, are the essence of the 'gentleman.' Often most provokingly so; for the things ignored may be of the deepest moral consequence. But in the very midst of our indignation with the gentleman, we have a consciousness that his preposterous inertia and negativeness in the actual emergency is, somehow or other, _allied_ with his general superiority to ourselves. It is not only that the gentleman ignores considerations relative to conduct, sordid suspicions, fears, calculations, etc., which the vulgarian is fated to entertain; it is that he is silent where the vulgarian talks; that he gives nothing but results where the vulgarian is profuse of reasons; that he does not explain or apologize; that he uses one sentence instead of twenty; and that, in a word, there is an amount of _interstitial_ thinking, so to call it, which it is quite impossible to get him to perform, but which is nearly all that the vulgarian mind performs at all. All this suppression of the secondary leaves the field _clear_,--for higher flights, should they choose to come. But even if they never came, what thoughts there were would still manifest the aristocratic type and wear the well-bred form. So great is our sense of harmony and ease in passing from the company of a philistine to that of an aristocratic temperament, that we are almost tempted to deem the falsest views and tastes as held by a man of the world, truer than the truest as held by a common person. In the latter the best ideas are choked, obstructed, and contaminated by the redundancy of their paltry associates. The negative conditions, at least, of an atmosphere and a free outlook are present in the former.

I may appear to have strayed from psychological analysis into æsthetic criticism. But the principle of selection is so important that no illustrations seem redundant which may help to show how great is its scope. The upshot of what I say simply is that selection implies rejection as well as choice; and that the function of ignoring, of _in_attention, is as vital a factor in mental progress as the function of attention itself.

      *       *       *       *       *

[319] The substance of this chapter, and a good many pages of the text, originally appeared in an article entitled 'Brute and Human Intellect,' in the Journal of Speculative Philosophy for July 1878 (vol. xii. p. 236).

[320] I see no need of assuming more than two terms in this sort of reasoning--first, the sign, and second, the thing inferred from it. Either may be complex, but essentially it is but A calling up B, and no middle term is involved. M. Binet, in his most intelligent little book, La Psychologie du Raisonnement, maintains that there are three terms. The present sensation or sign must, according to him, first evoke from the past an image which resembles it and fuses with it, and the things suggested or inferred are always the contiguous associates of this intermediate image, and not of the immediate sensation. The reader of Chapter XIX will see why I do not believe in the 'image' in question as a distinct psychic fact.

[321] Mental Evolution in Man (1889), chapters iii and iv. See especially pp. 68-80, and later 353, 396.

[322] _Loc. cit._ p. 50.

[323] P. 52.

[324] _Loc. cit._ p. 74.

[325] J. Locke, Essay conc. Hum. Understanding, bk. iv. chap. ii. § 3.

[326] To be sagacious is to be a good observer. J. S. Mill has a passage which is so much in the spirit of the text that I cannot forbear to quote it. "The observer is not he who merely sees the thing which is before his eyes, but he who sees what parts that thing is composed of. To do this well is a rare talent. One person, from inattention, or attending only in the wrong place, overlooks half of what he sees; another sets down much more than he sees, confounding it with what he imagines, or with what he infers; another takes note of the _kind_ of all the circumstances, but being inexpert in estimating their degree, leaves the quantity of each vague and uncertain; another sees indeed the whole, but makes such an awkward division of it into parts, throwing things into one mass which require to be separated, and separating others which might more conveniently be considered as one, that the result is much the same, sometimes even worse, than if no analysis had been attempted at all. It would be possible to point out what qualities of mind, and modes of mental culture, fit a person for being a good observer: that, however, is a question not of Logic, but of the Theory of Education, in the most enlarged sense of the term. There is not properly an Art of Observing. There may be rules for observing. But these, like rules for inventing, are properly instructions for the preparation of one's own mind; for putting it into the state in which it will be most fitted to observe, or most likely to invent. They are, therefore, essentially rules of self-education, which is a different thing from Logic. They do not teach how to do the thing, but how to make ourselves capable of doing it. They are an art of strengthening the limbs, not an art of using them. The extent and minuteness of observation which may be requisite, and the degree of decomposition to which it may be necessary to carry the mental analysis, depend on the particular purpose in view. To ascertain the state of the whole universe at any particular moment is impossible, but would also be useless. In making chemical experiments, we do not think it necessary to note the position of the planets; because experience has shown, as a very superficial experience is sufficient to show, that in such cases that circumstance is not material to the result: and accordingly, in the ages when man believed in the occult influences of the heavenly bodies, it might have been unphilosophical to omit ascertaining the precise condition of those bodies at the moment of the experiment." (Logic, bk. iii. chap. vii. § 1. Cf. also bk. iv. chap. ii.)

[327] Readers brought up on Popular Science may think that the molecular structure of things is their real essence in an absolute sense, and that water is H-O-H more deeply and truly than it is a solvent of sugar or a slaker of thirst. Not a whit! It is _all_ of these things with equal reality, and the only reason why _for the chemist_ it is H-O-H primarily, and only secondarily the other things, is that _for his purpose of deduction and compendious definition_, the H-O-H aspect of it is the more useful one to bear in mind.

[328] "We find that we take for granted irresistibly that each kind [of thing] has some character which distinguishes it from other classes.... What is the foundation of this postulate? What is the ground of this assumption that there must exist a definition which we have never seen, and which perhaps no one has seen in a satisfactory form?... I reply that our conviction that there must needs be characteristic marks by which things can be defined in words is founded upon the assumption of _the necessary possibility of reasoning_." (W. Whewell: Hist. of Scientific Ideas, bk. viii. chap. i, § 9.)

[329] I may quote a passage from an article entitled 'The Sentiment of Rationality,' published in vol. iv of Mind, 1879: "What is a _conception_? It is a _teleological instrument_. It is a partial aspect of a thing which _for our purpose_ we regard as its essential aspect, as the representative of the entire thing. In comparison with this aspect, whatever other properties and qualities the thing may have are unimportant accidents which we may without blame ignore. But the essence, the ground of conception, varies with the end we have in view. A substance like oil has as many different essences as it has uses to different individuals. One man conceives it as a combustible, another as a lubricator, another as a food; the chemist thinks of it as a hydrocarbon; the furniture-maker as a darkener of wood; the speculator as a commodity whose market-price to-day is this and to-morrow that. The soap-boiler, the physicist, the clothes-scourer severally ascribe to it other essences in relation to their needs. Ueberweg's doctrine that the essential quality of a thing is the quality of most _worth_ is strictly true; but Ueberweg has failed to note that the worth is wholly relative to the temporary interests of the conceiver. And, even, when his interest is distinctly defined in his own mind, the discrimination of the quality in the object which has the closest connection with it is a thing which no rules can teach. The only _a priori_ advice that can be given to a man embarking on life with a certain purpose is the somewhat barren counsel: Be sure that in the circumstances that meet you, you attend to the _right_ ones for your purpose. To pick out the right ones is the measure of the man. 'Millions,' says Hartmann, 'stare at the phenomenon before a _genialer Kopf_ pounces on the concept.' The genius is simply he to whom, when he opens his eyes upon the world, the 'right' characters are the prominent ones. The fool is he who, with the same purposes as the genius, infallibly gets his attention tangled amid the accidents."

[330] Only if one of our purposes were itself truer than another, could one of our conceptions become the truer conception. To be a truer purpose, however, our purpose must conform more to some absolute standard of purpose in things to which our purposes ought to conform. This shows that the whole doctrine of essential characters is intimately bound up with a teleological view of the world. Materialism becomes self-contradictory when it denies teleology, and yet in the same breath calls atoms, etc., the _essential_ facts. The world contains consciousness as well as atoms--and the one must be written down as just as essential as the other, in the absence of any declared purpose regarding them on the creator's part, or in the absence of any creator. As far as we ourselves go, the atoms are worth more for purposes of deduction, the consciousness for purposes of inspiration. We may fairly write the Universe in either way, thus: ATOMS-producing-consciousness; or CONSCIOUSNESS-produced-by-atoms. Atoms alone, or consciousness alone, are precisely equal mutilations of the truth. If, without believing in a God, I still continue to talk of what the world 'essentially is,' I am just as much entitled to define it as a place in which my nose itches, or as a place where at a certain corner I can get a mess of oysters for twenty cents, as to call it an evolving nebula differentiating and integrating itself. It is hard to say which of the three abstractions is the more rotten or miserable substitute for the world's concrete fulness. To conceive it merely as 'God's work' would be a similar mutilation of it, so long as we said not what God, or what kind of work. The only real truth about the world, apart from particular purposes, is the _total_ truth.

[331] Compare Lotze, Metaphysik, §§ 58, 67, for some instructive remarks on ways in which the world's constitution might differ from what it actually is. Compare also Chapter XXVIII.

[332] Sometimes, it must be confessed, the conceiver's purpose falls short of reasoning and the only conclusion he cares to reach is the bare naming of the datum. "What is that?" is our first question relative to any unknown thing. And the ease with which our curiosity is quenched as soon as we are supplied with any sort of a name to call the object by, is ridiculous enough. To quote from an unpublished essay by a former student of mine, Mr. R. W. Black: "The simplest end which a thing's predicate can serve is the satisfaction of the desire for unity itself, the mere desire that the thing shall be the same with _something_ else. Why, the other day, when I mistook a portrait of Shakespeare for one of Hawthorne, was I not, on psychological principles, as right as if I had correctly named it?--the two pictures had a common essence, bald forehead, mustache, flowing hair. Simply because the only end that could possibly be served by naming it Hawthorne was my desire to have it so. With reference to any other end that classification of it would not serve. And every unity, every identity, every classification is rightly called fanciful unless it serves some other end than the mere satisfaction, emotion, or inspiration caught by momentarily believing in it."

[333] See above, p. 8.

[334] See his Study of Character, chap. xv; also Senses and Intellect, 'Intellect,' chap. ii, the latter half.

[335] Whether the dog has the notion of your being angry or of your property being valuable in any such abstract way as _we_ have these notions is more than doubtful. The conduct is more likely an impulsive result of a conspiracy of outward stimuli; the beast _feels like_ acting so when these stimuli are present, though conscious of no definite reason why. The distinction of recept and concept is useful here. Some breeds of dogs, e.g. collies, seem instinctively to defend their master's property. The case is similar to that of a dog's barking at people after dark, at whom he would not bark in daylight. I have heard this quoted as evidence of the dog's reasoning power. It is only, as Chapter III has shown us, the impulsive result of a summation of stimuli, and has no connection with reasoning.

In certain stages of the hypnotic trance the subject seems to lapse into the non-analytic state. If a sheet of ruled foolscap paper, or a paper with a fine monotonous ornamental pattern printed on it, be shown to the subject, and _one_ of the ruled lines or elements of the pattern be pointed to for an instant, and the paper immediately removed, he will then almost always, when after a short interval the paper is presented to him again, pick out the indicated line or element with infallible correctness. The operator, meanwhile, has either to keep his eye fixed upon it, or to make sure of its position by counting, in order not to lose its place. Just so we may remember a friend's house in a street by the single character of its number rather than by its general look. The trance-subject would seem, in these instances, to surrender himself to the general look. He disperses his attention impartially over the sheet. The place of the particular line touched is part of a 'total effect' which he gets in its entirety, and which would be distorted if another line were touched instead. This total effect is lost upon the normal looker-on, bent as he is on concentration, analysis, and emphasis. What wonder, then, that, under these experimental conditions, the trance-subject excels him in touching the right line again? If he has time given him to count the line, he will excel the trance-subject; but if the time be too short to count, he will best succeed by following the trance-method, abstaining from analysis, and being guided by the 'general look' of the line's place on the sheet. One is surprised at one's success in this the moment one gives up one's habitually analytic state of mind.

Is it too much to say that we have in this dispersion of the attention and subjection to the 'general effect' something like a relapse into the state of mind of brutes? The trance-subject never gives any other reason for his optical discriminations, save that 'it looks so.' So a man, on a road once traversed inattentively before, takes a certain turn for no reason except that _he feels_ as if it must be right. He is guided by a sum of impressions, not one of which is emphatic or distinguished from the rest, not one of which is essential, not one of which is _conceived_, but all of which together drive him to a conclusion to which nothing but _that_ sum-total leads. Are not some of the wonderful discriminations of animals explicable in the same way? The cow finds her own stanchions in the long stable, the horse stops at the house he has once stopped at in the monotonous street, because no other stanchions, no other house, yield impartially _all_ the impressions of the previous experience. The man, however, by seeking to make some one impression characteristic and essential, prevents the rest from having their effect. So that, if the (for him) essential feature be forgotten or changed, he is too apt to be thrown off altogether, and then the brute or the trance-subject may seem to outstrip him in sagacity.

Dr. Romanes's already quoted distinction between 'receptual' and 'conceptual' thought (published since the body of my text and my note were written) connotes conveniently the difference which I seek to point out. See also his Mental Evolution in Man, p. 197 ff., for proofs of the fact that in a receptual way brutes cognize the mental states of other brutes and men.

[336] This matter of confusion is important and interesting. Since confusion is mistaking the wrong part of the phenomenon for the whole, whilst reasoning is, according to our definition, based on the substitution of the right part for the whole, it might be said that confusion and reasoning are generically the same process. I believe that they are so, and that the only difference between a muddle-head and a genius is that between extracting wrong characters and right ones. In other words, a muddle-headed person is a genius spoiled in the making. I think it will be admitted that all _eminently_ muddle-headed persons have the temperament of genius. They are constantly breaking away from the usual consecutions of concretes. A common associator by contiguity is too closely tied to routine to get muddle-headed.

[337] The horse is a densely stupid animal, as far as everything goes except contiguous association. We reckon him intelligent, partly because he looks so handsome, partly because he has such a wonderful faculty of contiguous association and can be so quickly moulded into a mass of set habits. Had he anything of reasoning intelligence, he would be a less faithful slave than he is.

[338] Th. Schumann: Journal Daheim, No. 19, 1878. Quoted by Strümpell: Die Geisteskräfte der Menschen verglicken mit denen der Thiere (Leipzig, 1878), p. 39. Cats are notorious for the skill with which they will open latches, locks, etc. Their feats are usually ascribed to their reasoning powers. But Dr. Romanes well remarks (Mental Evolution, etc., p. 351, note) that we ought first to be sure that the actions are not due to mere association. A cat is constantly playing with things with her paws; a trick accidentally hit upon may be retained. Romanes notes the fact that the animals most skilled in this way need not be the most generally intelligent, but those which have the best corporeal members for handling things, cat's paws, horse's lips, elephant's trunk, cow's horns. The monkey has both the corporeal and the intellectual superiority. And my deprecatory remarks on animal reasoning in the text apply far less to the quadrumana than to quadrupeds.--On the possible fallacies in interpreting animals' minds, compare C. L. Morgan in Mind, xi. 174 (1886).

[339] There are two other conditions of language in the human being, additional to association by similarity, that assist its action, or rather pave the way for it. These are: first, the great natural loquacity; and, second, the great imitativeness of man. The first produces the original reflex interjectional sign; the second (as Bleek has well shown) fixes it, stamps it, and ends by multiplying the number of determinate specific signs which are a requisite preliminary to the general conscious purpose of sign-making, which I have called the characteristic human element in language. The way in which imitativeness fixes the meaning of signs is this: When a primeval man has a given emotion, he utters his natural interjection; or when (to avoid supposing that the reflex sounds are exceedingly determinate by nature) a group of such men experience a common emotion, and one takes the lead in the cry, the others cry like him from sympathy or imitativeness. Now, let one of the group hear another, who is in presence of the experience, utter the cry; he, even without the experience, will repeat the cry from pure imitativeness. But, as he repeats the sign, he will be reminded by it of his own former experience. Thus, first, he has the sign with the emotion; then, without it; then, with it again. It is "dissociated by change of concomitants"; he feels it as a separate entity and yet as having a connection with the emotion. Immediately it becomes possible for him to couple it deliberately with the emotion, in cases where the latter would either have provoked no interjectional cry or not the same one. In a word, his mental procedure tends to _fix_ this cry on _that_ emotion; and when this occurs, in many instances, he is provided with a stock of signs, like the yelp, beg, rat of the dog, each of which suggests a determinate image. On this stock, then, similarity works in the way above explained.

[340] See the 'Evolution of Self-consciousness' in 'Philosophical Discussions,' by Chauncey Wright (New York: Henry Holt & Co., 1877). Dr. Romanes, in the book from which I have already quoted, seeks to show that the 'consciousness of truth as truth' and the deliberate intention to predicate (which are the characteristics of higher human reasoning) presuppose a consciousness of ideas as such, as things distinct from their objects; and that this consciousness depends on our having made signs for them by language. My text seems to me to include Dr. Romanes's facts, and formulates them in what to me is a more elementary way, though the reader who wishes to understand the matter better should go to his clear and patient exposition also.

[341] Study of Character, p. 317.

[342] Translated by my colleague, Professor G. H. Palmer.

[343] Quoted by Renouvier, Critique Philosophique, October 19, 1879.

[344] Social and domestic circumstances, that is, not material ones. Perceptions of social relations seem very keen in persons whose dealings with the material world are confined to knowing a few useful objects, principally animals, plants, and weapons. Savages and boors are often as tactful and astute socially as trained diplomatists. In general, it is probable that the consciousness of how one stands with other people occupies a relatively larger and larger part of the mind, the lower one goes in the scale of culture. Woman's intuitions, so fine in the sphere of personal relations, are seldom first-rate in the way of mechanics. All boys teach themselves how a clock goes: few girls. Hence Dr. Whately's jest, "Woman is the unreasoning animal, and pokes the fire from on top."



CHAPTER XXIII.

THE PRODUCTION OF MOVEMENT.


The reader will not have forgotten, in the jungle of purely inward processes and products through which the last chapters have borne him, that the final result of them all must be some form of bodily activity due to the escape of the central excitement through outgoing nerves. The whole neural organism, it will be remembered, is, physiologically considered, but a machine for converting stimuli into reactions; and the intellectual part of our life is knit up with but the middle or 'central' portion of the machine's operations. Let us now turn to consider the final or emergent operations, the bodily activities, and the forms of consciousness connected therewithal.

Every impression which impinges on the incoming nerves produces some discharge down the outgoing ones, whether we be aware of it or not. Using sweeping terms and ignoring exceptions, _we might say that every possible feeling produces a movement, and that the movement is a movement of the entire organism, and of each and all its parts._ What happens patently when an explosion or a flash of lightning startles us, or when we are tickled, happens latently with every sensation which we receive. The only reason why we do not feel the startle or tickle in the case of insignificant sensations is partly its very small amount, partly our obtuseness. Professor Bain many years ago gave the name of the Law of Diffusion to this phenomenon of general discharge, and expressed it thus: "According as an impression is accompanied with Feeling, the aroused currents diffuse themselves over the brain, leading to a general agitation of the moving organs, as well as affecting the viscera."

In cases where the feeling is strong the law is too familiar to require proof. As Prof. Bain says:

"Each of us knows in our own experience that a sudden shock of feeling
is accompanied with movements of the body generally, and with other
effects. When no emotion is present, we are quiescent; a slight
feeling is accompanied with slight manifestations; a more intense
shock has a more intense outburst. Every pleasure and every pain,
and every mode of emotion, has a definite wave of effects, which our
observation makes known to us; and we apply the knowledge to infer
other men's feelings from their outward display.... The organs first
and prominently affected, in the diffused wave of nervous influence,
are the moving members, and of these, by preference, the features
of the face (with the ears in animals), whose movements constitute
the _expression_ of the countenance. But the influence extends to
all the parts of the moving system, voluntary and involuntary;
while an important series of effects are produced on the glands and
viscera--the stomach, lungs, heart, kidneys, skin, together with the
sexual and mammary organs.... The circumstance is seemingly universal,
the proof of it does not require a citation of instances in detail; on
the objectors is thrown the burden of adducing unequivocal exceptions
to the law."[345]

There are probably no exceptions to the diffusion of every impression through the _nerve-centres_. The _effect_ of the wave through the centres may, however, often be to interfere with processes, and to diminish tensions already existing there; and the outward consequences of such inhibitions may be the arrest of discharges from the inhibited regions and the checking of bodily activities already in process of occurrence. When this happens it probably is like the draining or siphoning of certain channels by currents flowing through others. When, in walking, we suddenly stand still because a sound, sight, smell, or thought catches our attention, something like this occurs. But there are cases of arrest of peripheral activity which depend, not on central inhibition, but on stimulation of centres which discharge outgoing currents of an inhibitory sort. Whenever we are startled, for example, our heart momentarily stops or slows its beating, and then palpitates with accelerated speed. The brief arrest is due to an outgoing current down the pneumogastric nerve. This nerve, when stimulated, stops or slows the heart-beats, and this particular effect of startling fails to occur if the nerve be cut.

In general, however, the stimulating effects of a sense-impression preponderate over the inhibiting effects, so that we may roughly say, as we began by saying, that the wave of discharge produces an activity in all parts of the body. The task of tracing out _all_ the effects of any one incoming sensation has not yet been performed by physiologists. Recent years have, however, begun to enlarge our information; and although I must refer to special treatises for the full details, I can briefly string together here a number of separate observations which prove the truth of the law of diffusion.

[Illustration: FIG. 81.]

First take _effects upon the circulation_. Those upon the heart we have just seen. Haller long ago recorded that the blood from an open vein flowed out faster at the beat of a drum.[346] In Chapter III. (Vol. I. p. 98) we learned how instantaneously, according to Mosso, the circulation in the brain is altered by changes of sensation and of the course of thought. The effect of objects of fear, shame, and anger upon the blood-supply of the skin, especially the skin of the face, are too well known to need remark. Sensations of the higher senses produce, according to Couty and Charpentier, the most varied effects upon the pulse-rate and blood-pressure in dogs. Fig. 81, a pulse-tracing from these authors, shows the tumultuous effect on a dog's heart of hearing the screams of another dog. The changes of blood-pressure still occurred when the pneumogastric nerves were cut, showing the vaso-motor effect to be direct and not dependent on the heart. When Mosso invented that simple instrument, the _plethysmograph_, for recording the fluctuations in volume of the members of the body, what most astonished him, he says, "in the first experiments which he made in Italy, was the extreme unrest of the blood-vessels of the hand, which at every smallest emotion, whether during waking or during sleep, changed their volume in surprising fashion."[347] Figure 82 (from Féré[348]) shows the way in which the pulse of one subject was modified by the exhibition of a red light lasting from the moment marked _a_ to that marked _b_.

[Illustration: FIG. 82.]

[Illustration: FIG. 83.--Respiratory curve of B: _a_, with eyes open; _b_, with eyes closed.]

_The effects upon respiration_ of sudden sensory stimuli are also too well known to need elaborate comment. We 'catch our breath' at every sudden sound. We 'hold our breath' whenever our attention and expectation are strongly engaged, and we sigh when the tension of the situation is relieved. When a fearful object is before us we pant and cannot deeply inspire; when the object makes us angry it is, on the contrary, the act of expiration which is hard. I subjoin a couple of figures from Féré which explain themselves. They show the effects of light upon the breathing of two of his hysteric patients.[349]

[Illustration: FIG. 84. Respiratory curve of L: _a_, with yellow light; _b_ with green light; _c_, with red light. The red has the strongest effect.]

_On the sweat-glands,_ similar consequences of sensorial stimuli are observed. Tarchanoff, testing the condition of the sweat-glands by the power of the skin to start a galvanic current through electrodes applied to its surface, found that "nearly every kind of nervous activity, from the simplest sensations and impressions, to voluntary motions and the highest forms of mental exertion, is accompanied by an increased activity in the glands of the skin."[350] _On the pupil_ observations are recorded by Sanders which show that a transitory dilatation follows every sensorial stimulus applied _during sleep_, even if the stimulus be not strong enough to wake the subject up. At the moment of awaking there is a dilatation, even if strong light falls on the eye.[351] The pupil of children can easily be observed to dilate enormously under the influence of _fear_. It is said to dilate in pain and fatigue; and to contract, on the contrary, in rage.

As regards _effects on the abdominal viscera_, they unquestionably exist, but very few accurate observations have been made.[352]

The bladder, bowels, and uterus respond to sensations, even indifferent ones. Mosso and Pellicani, in their plethysmographic investigations on the bladder of dogs, found all sorts of sensorial stimuli to produce reflex contractions of this organ, independent of those of the abdominal walls. They call the bladder 'as good an æsthesiometer as the iris,' and refer to the not uncommon reflex effects of psychic stimuli in the human female upon this organ.[353] M. Féré has registered the contractions of the sphincter ani which even indifferent sensations will produce. In some pregnant women the fœtus is felt to move after almost every sensorial excitement received by the mother. The only natural explanation is that it is stimulated at such moments by reflex contractions of the womb.[354] That the glands are affected in emotion is patent enough in the case of the tears of grief, the dry mouth, moist skin, or diarrhœa of fear, the biliary disturbances which sometimes follow upon rage, etc. The watering of the mouth at the sight of succulent food is well known. It is difficult to follow the smaller degrees of all these reflex changes, but it can hardly be doubted that they exist in some degree, even where they cease to be traceable, and that all our sensations have some visceral effects. The sneezing produced by sunshine, the roughening of the skin (goose-flesh) which certain strokings, contacts, and sounds, musical or non-musical, provoke, are facts of the same order as the shuddering and standing up of the hair in fear, only of less degree.

_Effects on Voluntary Muscles._ Every sensorial stimulus not only sends a special discharge into certain particular muscles dependent on the special nature of the stimulus in question--some of these special discharges we have studied in Chapter XI, others we shall examine under the heads of Instinct and Emotion--but it innervates the muscles generally. M. Féré has given very curious experimental proofs of this. The strength of contraction of the subject's hand was measured by a self-registering dynamometer. Ordinarily the maximum strength, under simple experimental conditions, remains the same from day to day. But if simultaneously with the contraction the subject received a sensorial impression, the contraction was sometimes weakened, but more often increased. This reinforcing effect has received the name of _dynamogeny_. The dynamogenic value of simple _musical notes_ seems to be proportional to their loudness and height. Where the notes are compounded into sad strains, the muscular strength diminishes. If the strains are gay, it is increased.--The dynamogenic value of _colored lights_ varies with the color. In a subject[355] whose normal strength was expressed by 23, it became 24 when a blue light was thrown on the eyes, 28 for green, 30 for yellow, 35 for orange, and 42 for red. Red is thus the most exciting color. Among _tastes_, sweet has the lowest value, next comes salt, then bitter, and finally sour, though, as M. Féré remarks, such a sour as acetic acid excites the nerves of pain and smell as well as of taste. The stimulating effects of tobacco-smoke, alcohol, beef-extract (which is innutritious), etc., etc., may be partly due to a dynamogenic action of this sort.--Of _odors_, that of musk seems to have a peculiar dynamogenic power. Fig. 85 is a copy of one of M. Féré's dynamographic tracings, which explains itself. The smaller contractions are those without stimulus; the stronger ones are due to the influence of red rays of light.

[Illustration: FIG. 85.]

Everyone is familiar with the _patellar reflex_, or jerk upwards of the foot, which is produced by smartly tapping the tendon below the knee-pan when the leg hangs over the other knee. Drs. Weir Mitchell and Lombard have found that when other sensations come in simultaneously with the tap, the jerk is increased.[356] Heat, cold, pricking, itching, or faradic stimulation of the skin, sometimes strong optical impressions, music, all have this dynamogenic effect, which also results whenever voluntary movements are set up in other parts of the body, simultaneously with the tap.[357]

These 'dynamogenic' effects, in which one stimulation simply reinforces another already under way, must not be confounded with reflex acts properly so called, in which new activities are originated by the stimulus. All instinctive performances and manifestations of emotion are reflex acts. But underneath those of which we are conscious there seem to go on continually others smaller in amount, which probably in most persons might be called fluctuations of muscular _tone_, but which in certain neurotic subjects can be demonstrated ocularly. M. Féré figures some of them in the article to which I have already referred.[358]

      *       *       *       *       *

Looking back over all these facts, it is hard to doubt the truth of the law of diffusion, even where verification is beyond reach. _A process set up anywhere in the centres reverberates everywhere, and in some way or other affects the organism throughout, making its activities either greater or less._ We are brought again to the assimilation which was expressed on a previous page of the nerve-central mass to a good conductor charged with electricity, of which the tension cannot be changed anywhere without changing it everywhere.

      *       *       *       *       *

Herr Schneider has tried to show, by an ingenious and suggestive zoological review,[359] that all the _special_ movements which highly evolved animals make are differentiated from the two originally simple movements, of contraction and expansion, in which the entire body of simple organisms takes part. The tendency to contract is the source of all the self-protective impulses and reactions which are later developed, including that of flight. The tendency to expand splits up, on the contrary, into the impulses and instincts of an aggressive kind, feeding, fighting, sexual intercourse, etc. Schneider's articles are well worth reading, if only for the careful observations on animals which they embody. I cite them here as a sort of evolutionary reason to add to the mechanical _a priori_ reason why there _ought_ to be the diffusive wave which our _a posteriori_ instances have shown to exist.

I will now proceed to a detailed study of the more important classes of movement consequent upon cerebro-mental change. They may be enumerated as--

1) Instinctive or Impulsive Performances;

2) Expressions of Emotion; and

3) Voluntary Deeds;

and each shall have a chapter to itself.

      *       *       *       *       *

[345] Emotions and Will, pp. 4, 5.

[346] Cf. Féré. Sensation et Mouvement (1887), p. 56.

[347] La Paura (1884), p. 117. Compare Féré: Sensation et Mouvement, chap. xvii.

[348] Revue Philosophique, xxiv. 570.

[349] Revue Phil., xxiv. pp. 566-7.--For further information about the relations between the brain and respiration, see Danilewsky's Essay in the Biologisches Centralblatt, ii. 690.

[350] Quoted from the report of Tarchanoff's paper (in Pflüger's Archiv, xlvi. 46) in the American Journal of Psych., ii. 652.

[351] Archiv f. Psychiatrie, vii. 652; ix. 129.

[352] Sensation et Mouvement, 57-8.

[353] R. Accad. dei Lincei (1881-2). I follow the report in Hofmann Schwalbe's Jahresbericht, x. ii. 93.

[354] Cf. Féré, Sensation et Mouvement, chap. xiv.

[355] The figures given are from an hysterical subject, and the differences are greater than normal. M. Féré considers that the unstable nervous system of the hysteric ('ces grenouilles de la psychologie') shows the law on a quantitatively exaggerated scale, without altering the qualitative relations. The effects remind us a little of the influence of sensations upon minimal sensations of other orders discovered by Urbantschitsch, and reported on page 29 of this volume.

[356] Mitchell in (Philadelphia) Medical News (Feb. 13 and 20, 1886); Lombard in American Journal of Psychology (Oct. 1887).

[357] Prof. H. P. Bowditch has made the interesting discovery that if the reinforcing movement be as much as 0.4 of a second late, the reinforcement fails to occur, and is transformed into a positive inhibition of the knee-jerk for retardations of between 0.4' and 1.7'. The knee-jerk fails to be modified at all by voluntary movements made later than 1.7' after the patellar ligament is tapped (see Boston Med. and Surg. Journ., May 31, 1888).

[358] Revue Phil., xxiv. 572 ff.

[359] In the Vierteljahrschrift für wiss. Philos., iii. 294.



CHAPTER XXIV.[360]

INSTINCT.


_Instinct is usually defined as the faculty of acting in such a way as to produce certain ends, without foresight of the ends, and without previous education in the performance._ That instincts, as thus defined, exist on an enormous scale in the animal kingdom needs no proof. They are the functional correlatives of structure. With the presence of a certain organ goes, one may say, almost always a native aptitude for its use.

"Has the bird a gland for the secretion of oil? She knows
instinctively how to press the oil from the gland, and apply it to the
feather. Has the rattlesnake the grooved tooth and gland of poison?
He knows without instruction how to make both structure and function
most effective against his enemies. Has the silk-worm the function
of secreting the fluid silk? At the proper time she winds the cocoon
such as she has never seen, as thousands before have done; and thus
without instruction, pattern, or experience, forms a safe abode for
herself in the period of transformation. Has the hawk talons? She
knows by instinct how to wield them effectively against the helpless
quarry."[361]

A very common way of talking about these admirably definite tendencies to act is by naming abstractly the purpose they subserve, such as self-preservation, or defence, or care for eggs and young--and saying the animal has an instinctive fear of death or love of life, or that she has an instinct of self-preservation, or an instinct of maternity and the like. But this represents the animal as obeying abstractions which not once in a million cases is it possible it can have framed. The strict physiological way of interpreting the facts leads to far clearer results. _The actions we call instinctive all conform to the general reflex type;_ they are called forth by determinate sensory stimuli in contact with the animal's body, or at a distance in his environment. The cat runs after the mouse, runs or shows fight before the dog, avoids falling from walls and trees, shuns fire and water, etc., not because he has any notion either of life or of death, or of self, or of preservation. He has probably attained to no one of these conceptions in such a way as to react definitely upon it. He acts in each case separately, and simply because he cannot help it; being so framed that when that particular running thing called a mouse appears in his field of vision he _must_ pursue; that when that particular barking and obstreperous thing called a dog appears there he _must_ retire, if at a distance, and scratch if close by; that he _must_ withdraw his feet from water and his face from flame, etc. His nervous system is to a great extent a preorganized bundle of such reactions--they are as fatal as sneezing, and as exactly correlated to their special excitants as it is to its own. Although the naturalist may, for his own convenience, class these reactions under general heads, he must not forget that in the animal it is a particular sensation or perception, or image which calls them forth.

At first this view astounds us by the enormous number of special adjustments it supposes animals to possess ready-made in anticipation of the outer things among which they are to dwell. _Can_ mutual dependence be so intricate and go so far? Is each thing born fitted to particular other things, and to them exclusively, as locks are fitted to their keys? Undoubtedly this must be believed to be so. Each nook and cranny of creation, down to our very skin and entrails, has its living inhabitants, with organs suited to the place, to devour and digest the food it harbors and to meet the dangers it conceals; and the minuteness of adaptation thus shown in the way of _structure_ knows no bounds. Even so are there no bounds to the minuteness of adaptation in the way of _conduct_ which the several inhabitants display.

The older writings on instinct are ineffectual wastes of words, because their authors never came down to this definite and simple point of view, but smothered everything in vague wonder at the clairvoyant and prophetic power of the animals--so superior to anything in man--and at the beneficence of God in endowing them with such a gift. But God's beneficence endows them, first of all, with a nervous system; and, turning our attention to this, makes instinct immediately appear neither more nor less wonderful than all the other facts of life.

      *       *       *       *       *

_Every instinct is an impulse._ Whether we shall call such impulses as blushing, sneezing, coughing, smiling, or dodging, or keeping time to music, instincts or not, is a mere matter of terminology. The process is the same throughout. In his delightfully fresh and interesting work, Der Thierische Wille, Herr G. H. Schneider subdivides impulses (_Triebe_) into sensation-impulses, perception-impulses, and idea-impulses. To crouch from cold is a sensation-impulse; to turn and follow, if we see people running one way, is a perception-impulse; to cast about for cover, if it begins to blow and rain, is an imagination-impulse. A single complex instinctive action may involve successively the awakening of impulses of all three classes. Thus a hungry lion starts to _seek_ prey by the awakening in him of imagination coupled with desire; he begins to _stalk_ it when, on eye, ear, or nostril, he gets an impression of its presence at a certain distance; he _springs_ upon it, either when the booty takes alarm and flees, or when the distance is sufficiently reduced; he proceeds to _tear_ and _devour_ it the moment he gets a sensation of its contact with his claws and fangs. Seeking, stalking, springing, and devouring are just so many different kinds of muscular contraction, and neither kind is called forth by the stimulus appropriate to the other.

Schneider says of the hamster, which stores corn in its hole:

"If we analyze the propensity of storing, we find that it consists of
three impulses: First, an impulse to _pick up_ the nutritious object,
due to perception; second, an impulse to _carry it off_ into the
dwelling-place, due to the idea of this latter; and third, an impulse
to _lay it down_ there, due to the sight of the place. It lies in the
nature of the hamster that it should never see a full ear of corn
without feeling a desire to strip it; it lies in its nature to feel,
as soon as its cheek-pouches are filled, an irresistible desire to
hurry to its home; and finally, it lies in its nature that the sight
of the storehouse should awaken the impulse to empty the cheeks" (p.
208).

In certain animals of a low order the feeling of having executed one impulsive step is such an indispensable part of the stimulus of the next one, that the animal cannot make any variation in the order of its performance.

      *       *       *       *       *

_Now, why do the various animals do what seem to us such strange things,_ in the presence of such outlandish stimuli? Why does the hen, for example, submit herself to the tedium of incubating such a fearfully uninteresting set of objects as a nestful of eggs, unless she have some sort of a prophetic inkling of the result? The only answer is _ad hominem_. We can only interpret the instincts of brutes by what we know of instincts in ourselves. Why do men always lie down, when they can, on soft beds rather than on hard floors? Why do they sit round the stove on a cold day? Why, in a room, do they place themselves, ninety-nine times out of a hundred, with their faces towards its middle rather than to the wall? Why do they prefer saddle of mutton and champagne to hard-tack and ditch-water? Why does the maiden interest the youth so that everything about her seems more important and significant than anything else in the world? Nothing more can be said than that these are human ways, and that every creature _likes_ its own ways, and takes to the following them as a matter of course. Science may come and consider these ways, and find that most of them are useful. But it is not for the sake of their utility that they are followed, but because at the moment of following them we feel that that is the only appropriate and natural thing to do. Not one man in a billion, when taking his dinner, ever thinks of utility. He eats because the food tastes good and makes him want more. If you ask him _why_ he should want to eat more of what tastes like that, instead of revering you as a philosopher he will probably laugh at you for a fool. The connection between the savory sensation and the act it awakens is for him absolute and _selbstverständlich_, an '_a priori_ synthesis' of the most perfect sort, needing no proof but its own evidence. It takes, in short, what Berkeley calls a mind debauched by learning to carry the process of making the natural seem strange, so far as to ask for the _why_ of any instinctive human act. To the metaphysician alone can such questions occur as: Why do we smile, when pleased, and not scowl? Why are we unable to talk to a crowd as we talk to a single friend? Why does a particular maiden turn our wits so upside-down? The common man can only say, "_Of course_ we smile, _of course_ our heart palpitates at the sight of the crowd, _of course_ we love the maiden, that beautiful soul clad in that perfect form, so palpably and flagrantly made from all eternity to be loved!"

And so, probably, does each animal feel about the particular things it tends to do in presence of particular objects. They, too, are _a priori_ syntheses. To the lion it is the lioness which is made to be loved; to the bear, the she-bear. To the broody hen the notion would probably seem monstrous that there should be a creature in the world to whom a nestful of eggs was not the utterly fascinating and precious and never-to-be-too-much-sat-upon object which it is to her.[362]

Thus we may be sure that, however mysterious some animals' instincts may appear to us, our instincts will appear no less mysterious to them. And we may conclude that, to the animal which obeys it, every impulse and every step of every instinct shines with its own sufficient light, and seems at the moment the only eternally right and proper thing to do. It is done for its own sake exclusively. What voluptuous thrill may not shake a fly, when she at last discovers the one particular leaf, or carrion, or bit of dung, that out of all the world can stimulate her ovipositor to its discharge? Does not the discharge then seem to her the only fitting thing? And need she care or know anything about the future maggot and its food?

      *       *       *       *       *

Since the _egg-laying instincts_ are simple examples to consider, a few quotations about them from Schneider may be serviceable:

"The phenomenon so often talked about, so variously interpreted,
so surrounded with mystification, that an insect should always lay
her eggs in a spot appropriate to the nourishment of her young,
is no more marvellous than the phenomenon that every animal pairs
with a mate capable of bearing posterity, or feeds on materials
capable of affording him nourishment.... Not only the choice of a
place for laying the eggs, but all the various acts for depositing
and protecting them, are occasioned by the perception of the proper
object, and the relation of this perception to the various stages of
maternal impulse. When the burying beetle perceives a carrion, she is
not only impelled to approach it and lodge her eggs in it, but also
to go through the movements requisite for burying it; just us a bird
who sees his hen-bird is impelled to caress her, to strut around her,
dance before her, or in some other way to woo her; just as a tiger,
when he sees an antelope, is impelled to stalk it, to pounce upon it,
and to strangle it. When the tailor-bee cuts out pieces of rose-leaf,
bends them, carries them into a caterpillar- or mouse-hole in trees or
in the earth, covers their seams again with other pieces, and so makes
a thimble-shaped case--when she fills this with honey and lays an egg
in it, all these various appropriate expressions of her will are to be
explained by supposing that at the time when the eggs are ripe within
her, the appearance of a suitable caterpillar- or mouse-hole and the
perception of rose-leaves are so correlated in the insect with the
several impulses in question, that the performances follow as a matter
of course when the perceptions take place....
"The perception of the empty nest, or of a single egg, seems in birds
to stand in such a close relation to the physiological functions of
oviparation, that it serves as a direct stimulus to these functions,
while the perception of a sufficient number of eggs has just the
opposite effect. It is well known that hens and ducks lay more eggs if
we keep removing them than if we leave them in the nest. The impulse
to sit arises, as a rule, when a bird sees a certain number of eggs
in her nest. If this number is not yet to be seen there, the ducks
continue to lay, although they perhaps have laid twice as many eggs as
they are accustomed to sit upon.... That sitting, also, is independent
of any idea of purpose and is a pure perception-impulse is evident,
among other things, from the fact that many birds, e.g. wild ducks,
steal eggs from each other.... The bodily disposition to sit is, it
is true, one condition [since broody hens will sit where there are no
eggs], but the perception of the eggs is the other condition of the
activity of the incubating impulse. The propensity of the cuckoo and
of the cow-bird to lay their eggs in the nests of other species must
also be interpreted as a pure perception-impulse. These birds have no
bodily disposition to become broody, and there is therefore in them
no connection between the perception of an egg and the impulse to sit
upon it. Eggs ripen, however, in their oviducts, and the body tends to
get rid of them. And since the two birds just named do not drop their
eggs anywhere on the ground, but in nests, which are the only places
where they may preserve the species, it might easily appear that such
preservation of the species was what they had in view, and that they
acted with full consciousness of the purpose. But this is not so....
The cuckoo is simply excited by the perception of quite determinate
sorts of nest, which already contain eggs, to drop her own into them,
and throw the others out, because this perception is a direct stimulus
to these acts. It is impossible that she should have any notion of the
other bird coming and sitting on her egg."[363]


INSTINCTS NOT ALWAYS BLIND OR INVARIABLE.


Remember that nothing is said yet of the origin of instincts, but only of the constitution of those that exist fully formed. How stands it with the instincts of mankind?

Nothing is commoner than the remark that Man differs from lower creatures by the almost total absence of instincts, and the assumption of their work in him by 'reason.' A fruitless discussion might be waged on this point by two theorizers who were careful not to define their terms. 'Reason' might be used, as it often has been, since Kant, not as the mere power of 'inferring,' but also as a name for the _tendency to obey impulses_ of a certain lofty sort, such as duty, or universal ends. And 'instinct' might have its significance so broadened as to cover all impulses whatever, even the impulse to act from the idea of a distant fact, as well as the impulse to act from a present sensation. Were the word instinct used in this broad way, it would of course be impossible to restrict it, as we began by doing, to actions done with no prevision of an end. We must of course avoid a quarrel about words, and the facts of the case are really tolerably plain. Man has a far greater variety of _impulses_ than any lower animal; and any one of these impulses, taken in itself, is as 'blind' as the lowest instinct can be; but, owing to man's memory, power of reflection, and power of inference, they come each one to be felt by him, after he has once yielded to them and experienced their results, in connection with a _foresight_ of those results. In this condition an impulse acted out may be said to be acted out, in part at least, _for the sake_ of its results. It is obvious that _every instinctive act, in an animal with memory, must cease to be 'blind' after being once repeated,_ and must be accompanied with foresight of its 'end' just so far as that end may have fallen under the animal's cognizance. An insect that lays her eggs in a place where she never sees them hatched must always do so 'blindly;' but a hen who has already hatched a brood can hardly be assumed to sit with perfect 'blindness' on her second nest. Some expectation of consequences must in every case like this be aroused; and this expectation, according as it is that of something desired or of something disliked, must necessarily either re-enforce or inhibit the mere impulse. The hen's idea of the chickens would probably encourage her to sit; a rat's memory, on the other hand, of a former escape from a trap would neutralize his impulse to take bait from anything that reminded him of that trap. If a boy sees a fat hopping-toad, he probably has incontinently an impulse (especially if with other boys) to smash the creature with a stone, which impulse we may suppose him blindly to obey. But something in the expression of the dying toad's clasped hands suggests the meanness of the act, or reminds him of sayings he has heard about the sufferings of animals being like his own; so that, when next he is tempted by a toad, an idea arises which, far from spurring him again to the torment, prompts kindly actions, and may even make him the toad's champion against less reflecting boys.

It is plain, then, that, _no matter how well endowed an animal may originally be in the way of instincts, his resultant actions will be much modified if the instincts combine with experience,_ if in addition to impulses he have memories, associations, inferences, and expectations, on any considerable scale. An object O, on which he has an instinctive impulse to react in the manner A, would _directly_ provoke him to that reaction. But O has meantime become for him a _sign_ of the nearness of P, on which he has an equally strong impulse to react in the manner B, quite unlike A. So that when he meets O the immediate impulse A and the remote impulse B struggle in his breast for the mastery. The fatality and uniformity said to be characteristic of instinctive actions will be so little manifest that one might be tempted to deny to him altogether the possession of any instinct about the object O. Yet how false this judgment would be! The instinct about O is there; only by the complication of the associative machinery it has come into conflict with another instinct about P.

Here we immediately reap the good fruits of our simple physiological conception of what an instinct is. If it be a mere excito-motor impulse, due to the pre-existence of a certain 'reflex arc' in the nerve-centres of the creature, of course it must follow the law of all such reflex arcs. One liability of such arcs is to have their activity 'inhibited,' by other processes going on at the same time. It makes no difference whether the arc be organized at birth, or ripen spontaneously later, or be due to acquired habit, it must take its chances with all the other arcs, and sometimes succeed, and sometimes fail, in drafting off the currents through itself. The mystical view of an instinct would make it invariable. The physiological view would require it to show occasional irregularities in any animal in whom the number of separate instincts, and the possible entrance of the same stimulus into several of them, were great. And such irregularities are what every superior animal's instincts do show in abundance.[364]

Wherever the mind is elevated enough to discriminate; wherever several distinct sensory elements must combine to discharge the reflex-arc; wherever, instead of plumping into action instantly at the first rough intimation of what _sort_ of a thing is there, the agent waits to see which _one_ of its kind it is and what the _circumstances_ are of its appearance; wherever different individuals and different circumstances can impel him in different ways; wherever these are the conditions--we have a masking of the elementary constitution of the instinctive life. The whole story of our dealings with the lower wild animals is the history of our taking advantage of the way in which they judge of everything by its mere label, as it were, so as to ensnare or kill them. Nature, in them, has left matters in this rough way, and made them act _always_ in the manner which would be _oftenest_ right. There are more worms unattached to hooks than impaled upon them; therefore, on the whole, says Nature to her fishy children, bite at _every_ worm and take your chances. But as her children get higher, and their lives more precious, she reduces the risks. Since what seems to be the same object may be now a genuine food and now a bait; since in gregarious species each individual may prove to be either the friend or the rival, according to the circumstances, of another; since any entirely unknown object may be fraught with weal or woe, _Nature implants contrary impulses to act on many classes of things,_ and leaves it to slight alterations in the conditions of the individual case to decide which impulse shall carry the day. Thus, greediness and suspicion, curiosity and timidity, coyness and desire, bashfulness and vanity, sociability and pugnacity, seem to shoot over into each other as quickly, and to remain in as unstable equilibrium, in the higher birds and mammals as in man. They are all impulses, congenital, blind at first, and productive of motor reactions of a rigorously determinate sort. _Each one of them, then, is an instinct_, as instincts are commonly defined. _But they contradict each other_--'experience' in each particular opportunity of application usually deciding the issue. _The animal that exhibits them, loses the 'instinctive' demeanor_ and appears to lead a life of hesitation and choice, an intellectual life; _not, however, because he has no instincts--rather because he has so many that they block each other's path._

Thus, then, without troubling ourselves about the words instinct and reason, we may confidently say that however uncertain man's reactions upon his environment may sometimes seem in comparison with those of lower creatures, the uncertainty is probably not due to their possession of any principles of action which he lacks. _On the contrary, man possesses all the impulses that they have, and a great many more besides._ In other words, there is no material antagonism between instinct and reason. Reason, _per se_, can inhibit no impulses; the only thing that can neutralize an impulse is an impulse the other way. Reason may, however, make an _inference which will excite the imagination so as to set loose_ the impulse the other way; and thus, though the animal richest in reason might be also the animal richest in instinctive impulses too, he would never seem the fatal automaton which a _merely_ instinctive animal would be.

      *       *       *       *       *

Let us now turn to human impulses with a little more detail. All we have ascertained so far is that impulses of an originally instinctive character may exist, and yet not betray themselves by automatic fatality of conduct. But in man what impulses do exist? In the light of what has been said, it is obvious that an existing impulse may not always be superficially apparent even when its object is there. And we shall see that some impulses may be masked by causes of which we have not yet spoken.


TWO PRINCIPLES OF NON-UNIFORMITY IN INSTINCTS.


Were one devising an abstract scheme, nothing would be easier than to discover from an animal's actions just how many instincts he possessed. He would react in one way only upon each class of objects with which his life had to deal; he would react in identically the same way upon every specimen of a class; and he would react invariably during his whole life. There would be no gaps among his instincts; all would come to light without perversion or disguise. But there are no such abstract animals, and nowhere does the instinctive life display itself in such a way. Not only, as we have seen, may objects of the same class arouse reactions of opposite sorts in consequence of slight changes in the circumstances, in the individual object, or in the agent's inward condition; but two other principles of which we have not yet spoken, may come into play and produce results so striking that observers as eminent as Messrs. D. A. Spalding and Romanes do not hesitate to call them 'derangements of the mental constitution,' and to conclude that the instinctive machinery has got out of gear.

These principles are those

1. Of the _inhibition of instincts by habits_; and

2. Of the _transitoriness of instincts_.

Taken in conjunction with the two former principles--that the same object may excite ambiguous impulses, or _suggest_ an impulse different from that which it _excites_, by suggesting a remote object--they explain any amount of departure from uniformity of conduct, without implying any getting out of gear of the elementary impulses from which the conduct flows.

      *       *       *       *       *

1. The law of inhibition of instincts by habits is this: _When objects of a certain class elicit from an animal a certain sort of reaction, it often happens that the animal becomes partial to the first specimen of the class on which it has reacted, and will not afterward react on any other specimen._

The selection of a particular hole to live in, of a particular mate, of a particular feeding-ground, a particular variety of diet, a particular anything, in short, out of a possible multitude, is a very wide-spread tendency among animals, even those low down in the scale. The limpet will return to the same sticking-place in its rock, and the lobster to its favorite nook on the sea-bottom. The rabbit will deposit its dung in the same corner; the bird makes its nest on the same bough. But each of these preferences carries with it an insensibility to _other_ opportunities and occasions--an insensibility which can only be described physiologically as an inhibition of new impulses by the habit of old ones already formed. The possession of homes and wives of our own makes us strangely insensible to the charms of those of other people. Few of us are adventurous in the matter of food; in fact, most of us think there is something disgusting in a bill of fare to which we are unused. Strangers, we are apt to think, cannot be worth knowing, especially if they come from distant cities, etc. The original impulse which got us homes, wives, dietaries, and friends at all, seems to exhaust itself in its first achievements and to leave no surplus energy for reacting on new cases. And so it comes about that, witnessing this torpor, an observer of mankind might say that no _instinctive_ propensity toward certain objects existed at all. It existed, but it existed _miscellaneously_, or as an instinct pure and simple, only before habit was formed. A habit, once grafted on an instinctive tendency, restricts the range of the tendency itself, and keeps us from reacting on any but the habitual object, although other objects might just as well have been chosen had they been the first-comers.

Another sort of arrest of instinct by habit is where the same class of objects awakens contrary instinctive impulses. Here the impulse first followed toward a given individual of the class is apt to keep him from ever awakening the opposite impulse in us. In fact, the whole class may be protected by this individual specimen from the application to it of the other impulse. Animals, for example, awaken in a child the opposite impulses of fearing and fondling. But if a child, in his first attempts to pat a dog, gets snapped at or bitten, so that the impulse of fear is strongly aroused, it may be that for years to come no dog will excite in him the impulse to fondle again. On the other hand, the greatest natural enemies, if carefully introduced to each other when young and guided at the outset by superior authority, settle down into those 'happy families' of friends which we see in our menageries. Young animals, immediately after birth, have no instinct of fear, but show their dependence by allowing themselves to be freely handled. Later, however, they grow 'wild,' and, if left to themselves, will not let man approach them. I am told by farmers in the Adirondack wilderness that it is a very serious matter if a cow wanders off and calves in the woods and is not found for a week or more. The calf, by that time, is as wild and almost as fleet as a deer, and hard to capture without violence. But calves rarely show any particular wildness to the men who have been in contact with them during the first days of their life, when the instinct to attach themselves is uppermost, nor do they dread strangers as they would if brought up wild.

Chickens give a curious illustration of the same law. Mr. Spalding's wonderful article on instinct shall supply us with the facts. These little creatures show opposite instincts of attachment and fear, either of which may be aroused by the same object, man. If a chick is born in the absence of the hen, it

"will follow any moving object. And, when guided by sight alone, they
seem to have no more disposition to follow a hen than to follow a duck
or a human being. Unreflecting lookers-on, when they saw chickens
a day old running after me," says Mr. Spalding, "and older ones
following me for miles, and answering to my whistle, imagined that I
must have some occult power over the creatures: whereas I had simply
allowed them to follow me from the first. There is the instinct to
follow; and the ear, prior to experience, attaches them to the right
object."[365]

But if a man presents himself for the first time when the instinct of _fear_ is strong, the phenomena are altogether reversed. Mr. Spalding kept three chickens hooded until they were nearly four days old, and thus describes their behavior:

"Each of them, on being unhooded, evinced the greatest terror to me,
dashing off in the opposite direction whenever I sought to approach
it. The table on which they were unhooded stood before a window, and
each in its turn beat against the window like a wild bird. One of
them darted behind some books, and, squeezing itself into a corner,
remained cowering for a length of time. We might guess at the meaning
of this strange and exceptional wildness; but the odd fact is enough
for my present purpose. Whatever might have been the meaning of this
marked change in their mental constitution--had they been unhooded
on the previous day they would have run to me instead of from me--it
could not have been the effect of experience; it must have resulted
wholly from changes in their own organizations."[366]

Their case was precisely analogous to that of the Adirondack calves. The two opposite instincts relative to the same object ripen in succession. If the first one engenders a habit, that habit will inhibit the application of the second instinct to that object. All animals are tame during the earliest phase of their infancy. Habits formed then limit the effects of whatever instincts of wildness may later be evolved.

Mr. Romanes gives some very curious examples of the way in which instinctive tendencies may be altered by the habits to which their first 'objects' have given rise. The cases are a little more complicated than those mentioned in the text, inasmuch as the object reacted on not only starts a habit which inhibits other kinds of impulse toward it (although such other kinds might be natural), but even modifies by its own peculiar conduct the constitution of the impulse which it actually awakens.

Two of the instances in question are those of hens who hatched out broods of chicks after having (in three previous years) hatched ducks. They strove to coax or to compel their new progeny to enter the water, and seemed much perplexed at their unwillingness. Another hen adopted a brood of young ferrets which, having lost their mother, were put under her. During all the time they were left with her she had to sit on the nest, for they could not wander like young chicks. She obeyed their hoarse growling as she would have obeyed her chickens' peep. She combed out their hair with her bill, and "used frequently to stop and look with one eye at the wriggling nestful, with an inquiring gaze, expressive of astonishment." At other times she would fly up with a loud scream, doubtless because the orphans had nipped her in their search for teats. Finally, a Brahma hen nursed a young peacock during the enormous period of _eighteen months_, and never laid any eggs during all this time. The abnormal degree of pride which she showed in her wonderful chicken is described by Dr. Romanes as ludicrous.[367]

2. This leads us to the _law of transitoriness_, which is this: _Many instincts ripen at a certain age and then fade away._ A consequence of this law is that if, during the time of such an instinct's vivacity, objects adequate to arouse it are met with, a _habit_ of acting on them is formed, which remains when the original instinct has passed away; but that if no such objects are met with, then no habit will be formed; and, later on in life, when the animal meets the objects, he will altogether fail to react, as at the earlier epoch he would instinctively have done.

No doubt such a law is restricted. Some instincts are far less transient than others--those connected with feeding and 'self-preservation' may hardly be transient at all, and some, after fading out for a time, recur as strong as ever, e.g., the instincts of pairing and rearing young. The law, however, though not absolute, is certainly very widespread, and a few examples will illustrate just what it means.

In the chickens and calves above mentioned, it is obvious that the instinct to follow and become attached fades out after a few days, and that the instinct of flight then takes its place, the conduct of the creature toward man being decided by the formation or non-formation of a certain habit during those days. The transiency of the chicken's instinct to follow is also proved by its conduct toward the hen. Mr. Spalding kept some chickens shut up till they were comparatively old, and, speaking of these, he says:

"A chicken that has not heard the call of the mother till until eight
or ten days old then hears it as if it heard it not. I regret to
find that on this point my notes are not so full as I could wish,
or as they might have been. There is, however, an account of one
chicken that could not be returned to the mother when ten days old.
The hen followed it, and tried to entice it in every way; still, it
continually left her and ran to the house or to any person of whom it
caught sight. This it persisted in doing, though beaten back with a
small branch dozens of times, and, indeed, cruelly maltreated. It was
also placed under the mother at night, but it again left her in the
morning."

The instinct of sucking is ripe in all mammals at birth, and leads to that habit of taking the breast which, in the human infant, may be prolonged by daily exercise long beyond its usual term of a year or a year and a half. But the instinct itself is transient, in the sense that if, for any reason, the child be fed by spoon during the first few days of its life and not put to the breast, it may be no easy matter after that to make it suck at all. So of calves. If their mother die, or be dry, or refuse to let them suck for a day or two, so that they are fed by hand, it becomes hard to get them to suck at all when a new nurse is provided. The ease with which sucking creatures are weaned, by simply breaking the habit and giving them food in a new way, shows that the instinct, purely as such, must be entirely extinct.

Assuredly the simple fact that instincts are transient, and that the effect of later ones may be altered by the habits which earlier ones have left behind, is a far more philosophical explanation than the notion of an instinctive constitution vaguely 'deranged' or 'thrown out of gear.'

I have observed a Scotch terrier, born on the floor of a stable in December, and transferred six weeks later to a carpeted house, make, when he was less than four months old, a very elaborate pretence of burying things, such as gloves, etc., with which he had played till he was tired. He scratched the carpet with his forefeet, dropped the object from his mouth upon the spot, and then scratched all about it (with both fore-and hind-feet, if I remember rightly), and finally went away and let it lie. Of course, the act was entirely useless. I saw him perform it at that age, some four or five times, and never again in his life. The conditions were not present to fix a habit which should last when the prompting instinct died away. But suppose meat instead of a glove, earth instead of a carpet, hunger-pangs instead of a fresh supper a few hours later, and it is easy to see how this dog might have got into a habit of burying superfluous food, which might have lasted all his life. Who can swear that the strictly instructive part of the food-burying propensity in the wild _Canidæ_ may not be as short-lived as it was in this terrier?

A similar instance is given by Dr. H. D. Schmidt[368] of New Orleans:

"I may cite the example of a young squirrel which I had tamed,
a number of years ago, when serving in the army, and when I had
sufficient leisure and opportunity to study the habits of animals.
In the autumn, before the winter sets in, adult squirrels bury as
many nuts as they can collect, separately, in the ground. Holding
the nut firmly between their teeth, they first scratch a hole in the
ground, and, after pointing their ears in all directions to convince
themselves that no enemy is near, they ram--the head, with the nut
still between the front teeth, serving as a sledge-hammer--the nut
into the ground, and then fill up the hole by means of their paws. The
whole process is executed with great rapidity, and, as it appeared
to me, always with exactly the same movements; in fact, it is done
so well that I could never discover the traces of the burial-ground.
Now, as regards the young squirrel, which, of course, never had been
present at the burial of a nut, I observed that, after having eaten
a number of hickory-nuts to appease its appetite, it would take one
between its teeth, then sit upright and listen in all directions.
Finding all right, it would scratch upon the smooth blanket on which
I was playing with it as if to make a hole, then hammer with the
nut between its teeth upon the blanket, and finally perform all the
motions required to fill up a hole_--in the air_; after which it would
jump away, leaving the nut, of course, uncovered."

The anecdote, of course, illustrates beautifully the close relation of instinct to reflex action--a particular perception calls forth particular movements, and that is all. Dr. Schmidt writes me that the squirrel in question soon passed away from his observation. It may fairly be presumed that, if he had been long retained prisoner in a cage, he would soon have forgotten his gesticulations over the hickory-nuts.

One might, indeed, go still further with safety, and expect that, if such a captive squirrel were then set free, he would never afterwards acquire this peculiar instinct of his tribe.[369]

      *       *       *       *       *

Leaving lower animals aside, and turning to human instincts, we see the law of transiency corroborated on the widest scale by the alternation of different interests and passions as human life goes on. With the child, life is all play and fairy-tales and learning the external properties of 'things;' with the youth, it is bodily exercises of a more systematic sort, novels of the real world, boon-fellowship and song, friendship and love, nature, travel and adventure, science and philosophy; with the man, ambition and policy, acquisitiveness, responsibility to others, and the selfish zest of the battle of life. If a boy grows up alone at the age of games and sports, and learns neither to play ball, nor row, nor sail, nor ride, nor skate, nor fish, nor shoot, probably he will be sedentary to the end of his days; and, though the best of opportunities be afforded him for learning these things later, it is a hundred to one but he will pass them by and shrink back from the effort of taking those necessary first steps the prospect of which, at an earlier age, would have filled him with eager delight. The sexual passion expires after a protracted reign; but it is well known that its peculiar manifestations in a given individual depend almost entirely on the habits he may form during the early period of its activity. Exposure to bad company then makes him a loose liver all his days; chastity kept at first makes the same easy later on. In all pedagogy the great thing is to strike the iron while hot, and to seize the wave of the pupil's interest in each successive subject before its ebb has come, so that knowledge may be got and a habit of skill acquired--a headway of interest, in short, secured, on which afterward the individual may float. There is a happy moment for fixing skill in drawing, for making boys collectors in natural history, and presently dissectors and botanists; then for initiating them into the harmonies of mechanics and the wonders of physical and chemical law. Later, introspective psychology and the metaphysical and religious mysteries take their turn; and, last of all, the drama of human affairs and worldly wisdom in the widest sense of the term. In each of us a saturation-point is soon reached in all these things; the impetus of our purely intellectual zeal expires, and unless the topic be one associated with some urgent personal need that keens our wits constantly whetted about it, we settle into an equilibrium, and live on what we learned when our interest was fresh and instinctive, without adding to the store. Outside of their own business, the ideas gained by men before they are twenty-five are practically the only ideas they shall have in their lives. They _cannot_ get anything new. Disinterested curiosity is past, the mental grooves and channels set, the power of assimilation gone. If by chance we ever do learn anything about some entirely new topic we are afflicted with a strange sense of insecurity, and we fear to advance a resolute opinion. But, with things learned in the plastic days of instinctive curiosity we never lose entirely our sense of being at home. There remains a kinship, a sentiment of intimate acquaintance, which, even when we know we have failed to keep abreast of the subject, flatters us with a sense of power over it, and makes us feel not altogether out of the pale.

Whatever individual exceptions might be cited to this are of the sort that 'prove the rule.'

To detect the moment of the instinctive readiness for the subject is, then, the first duty of every educator. As for the pupils, it would probably lead to a more earnest temper on the part of college students if they had less belief in their unlimited future intellectual potentialities, and could be brought to realize that whatever physics and political economy and philosophy they are now acquiring are, for better or worse, the physics and political economy and philosophy that will have to serve them to the end.

The natural conclusion to draw from this transiency of instincts is that _most instincts are implanted for the sake of giving rise to habits, and that, this purpose once accomplished, the instincts themselves, as such, have no raison d'être in the psychical economy, and consequently fade away._ That occasionally an instinct should fade before circumstances permit of a habit being formed, or that, if the habit be formed, other factors than the pure instinct should modify its course, need not surprise us. Life is full of the imperfect adjustment to individual cases, of arrangements which, taking the species as a whole, are quite orderly and regular. Instinct cannot be expected to escape this general risk.


SPECIAL HUMAN INSTINCTS.


Let us now test our principles by turning to human instincts in more detail. We cannot pretend in these pages to be minute or exhaustive. But we can say enough to set all the above generalities in a more favorable light. But first, what kind of motor reactions upon objects shall we count as instincts? This, as aforesaid, is a somewhat arbitrary matter. Some of the actions aroused in us by objects go no further than our own bodies. Such is the bristling up of the attention when a novel object is perceived, or the 'expression' on the face or the breathing apparatus of an emotion it may excite. These movements merge into ordinary reflex actions like laughing when tickled, or making a wry face at a bad taste. Other actions take effect upon the outer world. Such are flight from a wild beast, imitation of what we see a comrade do, etc. On the whole it is best to be catholic, since it is very hard to draw an exact line; and call both of these kinds of activity instinctive, so far as either may be _naturally_ provoked by the presence of specific sorts of outward fact.

Professor Preyer, in his careful little work, 'Die Seele des Kindes,' says "instinctive acts are in man few in number, and, apart from those connected with the sexual passion, difficult to recognize after early youth is past." And he adds, "so much the more attention should we pay to the instinctive movements of new-born babies, sucklings, and small children." That instinctive acts should be easiest _recognized_ in childhood would be a very natural effect of our principles of transitoriness, and of the restrictive influence of habits once acquired; but we shall see how far they are from being 'few in number' in man. Professor Preyer divides the movements of infants into _impulsive, reflex,_ and instinctive. By impulsive movements he means _random_ movements of limbs, body, and voice, with no aim, and before perception is aroused. Among the first reflex movements are crying on contact with the air, _sneezing, snuffling, snoring, coughing, sighing, sobbing, gagging, vomiting, hiccuping, starting, moving the limbs when tickled, touched, or blown upon,_ etc., etc.

Of the movements called by him instinctive in the child, Professor Preyer gives a full account. Herr Schneider does the same; and as their descriptions agree with each other and with what other writers about infancy say, I will base my own very brief statement on theirs.

_Sucking_: almost perfect at birth; not coupled with any congenital tendency to _seek_ the breast, this being a later acquisition. As we have seen, sucking is a transitory instinct.

_Biting_ an object placed in the mouth, _chewing_ and _grinding the teeth; licking_ sugar; making characteristic _grimaces_ over bitter and sweet tastes; _spitting_ out.

_Clasping_ an object which touches the fingers or toes. Later, attempts to _grasp_ at an object seen at a distance. _Pointing at_ such objects, and making a peculiar _sound expressive of desire_, which, in my own three children, was the first manifestation of speech, occurring many weeks before other significant sounds.

_Carrying to the mouth_ of the object, when grasped. This instinct, guided and inhibited by the sense of taste, and combined with the instincts of biting, chewing, sucking, spitting-out, etc., and with the reflex act of swallowing, leads in the individual to a set of habits which constitute his _function of alimentation_, and which may or may not be gradually modified as life goes on.

_Crying_ at bodily discomfort, hunger, or pain, and at solitude. _Smiling_ at being noticed, fondled, or smiled at by others. It seems very doubtful whether young infants have any instinctive fear of a terrible or scowling face. I have been unable to make my own children, under a year old, change their expression when I changed mine; at most they manifested attention or curiosity. Preyer instances a _protrusion of the lips_, which, he says, may be so great as to remind one of that in the chimpanzee, as an instinctive expression of concentrated attention in the human infant.

_Turning the head aside_ as a gesture of rejection, a gesture usually accompanied with a frown and a bending back of the body, and with holding the breath.

_Holding head erect._

_Sitting up._

_Standing_.

_Locomotion_. The early movements of children's limbs are more or less symmetrical. Later a baby will move his legs in alternation if suspended in the air. But until the impulse to walk awakens by the natural ripening of the nerve-centres, it seems to make no difference how often the child's feet may be placed in contact with the ground; the legs remain limp, and do not respond to the sensation of contact in the soles by muscular contractions _pressing downwards_. No sooner, however, is the standing impulse born, than the child stiffens his legs and presses downward as soon as he feels the floor. In some babies this is the first locomotory reaction. In others it is preceded by the instinct to _creep_, which arises, as I can testify, often in a very sudden way. Yesterday the baby sat quite contentedly wherever he was put; to-day it has become impossible to keep him sitting at all, so irresistible is the impulse, aroused by the sight of the floor, to throw himself forward upon his hands. Usually the arms are too weak, and the ambitious little experimenter falls on his nose. But his perseverance is dauntless, and he ends in a few days by learning to travel rapidly around the room in the quadrupedal way. The position of the legs in 'creeping' varies much from one child to another. My own child, when creeping, was often observed to pick up objects from the floor with his mouth, a phenomenon which, as Dr. O. W. Holmes has remarked, like the early tendency to grasp with the toes, easily lends itself to interpretation as a reminiscence of prehuman ancestral habits.

The walking instinct may awaken with no less suddenness, and its entire education be completed within a week's compass, barring, of course, a little 'grogginess' in the gait. Individual infants vary enormously; but on the whole it is safe to say that the mode of development of these locomotor instincts is inconsistent with the account given by the older English associationist school, of their being results of the individual's education, due altogether to the gradual association of certain perceptions with certain haphazard movements and certain resultant pleasures. Mr. Bain has tried,[370] by describing the demeanor of new-born lambs, to show that locomotion is _learned_ by a very rapid experience. But the observation recorded proves the faculty to be almost perfect from the first; and all others who have observed new-born calves, lambs, and pigs agree that in these animals the powers of standing and walking, and of interpreting the topographical significance of sights and sounds, are all but fully developed at birth. Often in animals who seem to be 'learning' to walk or fly the semblance is illusive. The awkwardness shown is not due to the fact that 'experience' has not yet been there to associate the successful movements and exclude the failures, but to the fact that the animal is beginning his attempts before the co-ordinating centres have quite ripened for their work. Mr. Spalding's observations on this point are conclusive as to birds.

"Birds," he says, "do not _learn_ to fly. Two years ago I shut up five
unfledged swallows in a small box, not much larger than the nest from
which they were taken. The little box, which had a wire front, was
hung on the wall near the nest, and the young swallows were fed by
their parents through the wires. In this confinement, where they could
not even extend their wings, they were kept until after they were
fully fledged.... On going to set the prisoners free, one was found
dead.... The remaining four were allowed to escape one at a time. Two
of these were perceptibly wavering and unsteady in their flight. One
of them, after a flight of some ninety yards, disappeared among some
trees." No. 3 and No. 4 "never flew against anything, nor was there,
in their avoiding objects, any appreciable difference between them and
the old birds. No. 3 swept round the Wellingtonia, and No. 4 rose over
the hedge, just as we see the old swallows doing every hour of the
day. I have this summer verified these observations. Of two swallows
I had similarly confined, one, on being set free, flew a yard or two
close to the ground, rose in the direction of a beech-tree, which
it gracefully avoided; it was seen for a considerable time sweeping
round the beeches and performing magnificent evolutions in the air
high above them. The other, which was observed to beat the air with
its wings more than usual, was soon lost to sight, behind some trees.
Titmice, tomtits, and wrens I have made the subjects of similar
observations, and with similar results."[371]

In the light of this report, one may well be tempted to make a prediction about the human child, and say that if a baby were kept from getting on his feet for two or three weeks after the first impulse to walk had shown itself in him,--a small blister on each sole would do the business,--he might then be expected to walk about as well, through the mere ripening of his nerve-centres, as if the ordinary process of 'learning' had been allowed to occur during all the blistered time. It is to be hoped that some scientific widower, left alone with his offspring at the critical moment, may ere long test this suggestion on the living subject. _Climbing_ on trees, fences, furniture, banisters, etc., is a well-marked instinctive propensity which ripens after the fourth year.

_Vocalization._ This may be either musical or significant. Very few weeks after birth the baby begins to express its spirits by emitting vowel sounds, as much during inspiration as during expiration, and will lie on its back cooing and gurgling to itself for nearly an hour. But this singing has nothing to do with speech. Speech is sound _significant_. During the second year a certain number of significant sounds are gradually acquired; but talking proper does not set in till the instinct to _imitate sounds_ ripens in the nervous system; and this ripening seems in some children to be quite abrupt. Then speech grows rapidly in extent and perfection. The child imitates every word he hears uttered, and repeats it again and again with the most evident pleasure at his new power. At this time it is quite impossible to talk _with_ him, for his condition is that of 'Echolalia,'--instead of answering the question, he simply reiterates it. The result is, however, that his vocabulary increases very fast; and little by little, with teaching from above, the young prattler understands, puts words together to express his own wants and perceptions, and even makes intelligent replies. From a speechless, he has become a speaking, animal. The interesting point with regard to this instinct is the oftentimes very sudden birth of the impulse to imitate sounds. Up to the date of its awakening the child may have been as devoid of it as a dog. Four days later his whole energy may be poured into this new channel. The habits of articulation formed during the plastic age of childhood are in most persons sufficient to inhibit the formation of new ones of a fundamentally different sort--witness the inevitable 'foreign accent' which distinguishes the speech of those who learn a language after early youth.

_Imitation._ The child's first words are in part vocables of his own invention, which his parents adopt, and which, as far as they go, form a new human tongue upon the earth; and in part they are his more or less successful imitations of words he hears the parents use. But the instinct of _imitating gestures_ develops earlier than that of imitating sounds,--unless the sympathetic crying of a baby when it hears another cry may be reckoned as imitation of a sound. Professor Preyer speaks of his child imitating the protrusion of the father's lips in its fifteenth week. The various accomplishments of infancy, making 'pat-a-cake,' saying 'bye-bye,' 'blowing out the candle,' etc., usually fall well inside the limits of the first year. Later come all the various imitative games in which childhood revels, playing 'horse,' 'soldiers,' etc., etc. And from this time onward man is essentially _the_ imitative animal. His whole educability and in fact the whole history of civilization depend on this trait, which his strong tendencies to rivalry, jealousy, and acquisitiveness reinforce. '_Humani nihil a me alienum puto_,' is the motto of each individual of the species; and makes him, whenever another individual shows a power or superiority of any kind, restless until he can exhibit it himself. But apart from this kind of imitation, of which the psychological roots are complex, there is the more direct propensity to speak and walk and behave like others, usually without any conscious intention of so doing. And there is the imitative tendency which shows itself in large masses of men, and produces panics, and orgies, and frenzies of violence, and which only the rarest individuals can actively withstand. This sort of imitativeness is possessed by man in common with other gregarious animals, and is an instinct in the fullest sense of the term, being a blind impulse to act as soon as a certain perception occurs. It is particularly hard not to imitate gaping, laughing, or looking and running in a certain direction, if we see others doing so. Certain mesmerized subjects must automatically imitate whatever motion their operator makes before their eyes.[372] A successful piece of mimicry gives to both bystanders and mimic a peculiar kind of æsthetic pleasure. The dramatic impulse, the tendency to pretend one is someone else, contains this pleasure of mimicry as one of its elements. Another element seems to be a peculiar sense of power in stretching one's own personality so as to include that of a strange person. In young children this instinct often knows no bounds. For a few months in one of my children's third year, he literally hardly ever appeared in his own person. It was always, "Play I am So-and-so, and you are So-and-so, and the chair is such a thing, and then we'll do this or that." If you called him by his name, H., you invariably got the reply, "I'm not H., I'm a hyena, or a horse-car," or whatever the feigned object might be. He outwore this impulse after a time; but while it lasted, it had every appearance of being the automatic result of ideas, often suggested by perceptions, working out irresistible motor effects. Imitation shades into

_Emulation or Rivalry,_ a very intense instinct, especially rife with young children, or at least especially undisguised. Everyone knows it. Nine-tenths of the work of the world is done by it. We know that if we do not do the task someone else will do it and get the credit, so we do it. It has very little connection with sympathy, but rather more with pugnacity, which we proceed in turn to consider.

_Pugnacity; anger; resentment._ In many respects man is the most ruthlessly ferocious of beasts. As with all gregarious animals, 'two souls,' as Faust says, 'dwell within his breast,' the one of sociability and helpfulness, the other of jealousy and antagonism to his mates. Though in a general way he cannot live without them, yet, as regards certain individuals, it often falls out that he cannot live with them either. Constrained to be a member of a tribe, he still has a right to decide, as far as in him lies, of which other members the tribe shall consist. Killing off a few obnoxious ones may often better the chances of those that remain. And killing off a neighboring tribe from whom no good thing comes, but only competition, may materially better the lot of the whole tribe. Hence the gory cradle, the _bellum omnium contra omnes_, in which our race was reared; hence the fickleness of human ties, the ease with which the foe of yesterday becomes the ally of to-day, the friend of to-day the enemy of to-morrow; hence the fact that we, the lineal representatives of the successful enactors of one scene of slaughter after another, must, whatever more pacific virtues we may also possess, still carry about with us, ready at any moment to burst into flame, the smouldering and sinister traits of character by means of which they lived through so many massacres, harming others, but themselves unharmed.

_Sympathy_ is an emotion as to whose instinctiveness psychologists have held hot debate, some of them contending that it is no primitive endowment, but, originally at least, the result of a rapid calculation of the good consequences to ourselves of the sympathetic act. Such a calculation, at first conscious, would grow more unconscious as it became more habitual, and at last, tradition and association aiding, might prompt to actions which could not be distinguished from immediate impulses. It is hardly needful to argue against the falsity of this view. Some forms of sympathy, that of mother with child, for example, are surely primitive, and not intelligent forecasts of board and lodging and other support to be reaped in old age. Danger to the child blindly and instantaneously stimulates the mother to actions of alarm or defence. Menace or harm to the adult beloved or friend excites us in a corresponding way, often against all the dictates of prudence. It is true that sympathy does not necessarily follow from the mere fact of gregariousness. Cattle do not help a wounded comrade; on the contrary, they are more likely to dispatch him. But a dog will lick another sick dog, and even bring him food; and the sympathy of monkeys is proved by many observations to be strong. In man, then, we may lay it down that the sight of suffering or danger to others is a direct exciter of interest, and an immediate stimulus, if no complication hinders, to acts of relief. There is nothing unaccountable or pathological about this--nothing to justify Professor Bain's assimilation of it to the 'fixed ideas' of insanity, as 'clashing with the regular outgoings of the will.' It may be as primitive as any other 'outgoing,' and may be due to a random variation selected, quite as probably as gregariousness and maternal love are, even in Spencer's opinion, due to such variations.

It is true that sympathy is peculiarly liable to inhibition from other instincts which its stimulus may call forth. The traveller whom the good Samaritan rescued may well have prompted such instinctive fear or disgust in the priest and Levite who passed him by, that their sympathy could not come to the front. Then, of course, habits, reasoned reflections, and calculations may either check or reinforce one's sympathy; as may also the instincts of love or hate, if these exist, for the suffering individual. The hunting and pugnacious instincts, when aroused, also inhibit our sympathy absolutely. This accounts for the cruelty of collections of men hounding each other on to bait or torture a victim. The blood mounts to the eyes, and sympathy's chance is gone.[373]

_The hunting instinct_ has an equally remote origin in the evolution of the race.[374] The hunting and the fighting instinct combine in many manifestations. They both support the emotion of anger; they combine in the fascination which stories of atrocity have for most minds; and the utterly blind excitement of giving the rein to our fury when our blood is up (an excitement whose intensity is greater than that of any other human passion save one) is only explicable as an impulse aboriginal in character, and having more to do with immediate and overwhelming tendencies to muscular discharge than to any possible reminiscences of effects of experience, or association of ideas. I say this here, because the pleasure of disinterested cruelty has been thought a paradox, and writers have sought to show that it is no primitive attribute of our nature, but rather a resultant of the subtile combination of other less malignant elements of mind. This is a hopeless task. If evolution and the survival of the fittest be true at all, the destruction of prey and of human rivals _must_ have been among the most important of man's primitive functions, the fighting and the chasing instincts _must_ have become ingrained. Certain perceptions _must_ immediately, and without the intervention of inferences and ideas, have prompted emotions and motor discharges; and both the latter must, from the nature of the case, have been very violent, and therefore, when unchecked, of an intensely pleasurable kind. It is just because human bloodthirstiness is such a primitive part of us that it is so hard to eradicate, especially where a fight or a hunt is promised as part of the fun.[375]

As Rochefoucauld says, there is something in the misfortunes of our very friends that does not altogether displease us; and an apostle of peace will feel a certain vicious thrill run through him, and enjoy a vicarious brutality, as he turns to the column in his newspaper at the top of which 'Shocking Atrocity' stands printed in large capitals. See how the crowd flocks round a street-brawl! Consider the enormous annual sale of revolvers to persons, not one in a thousand of whom has any serious intention of using them, but of whom each one has his carnivorous self-consciousness agreeably tickled by the notion, as he clutches the handle of his weapon, that he will be rather a dangerous customer to meet. See the ignoble crew that escorts every great pugilist--parasites who feel as if the glory of his brutality rubbed off upon them, and whose darling hope, from day to day, is to arrange some set-to of which they may share the rapture without enduring the pains! The first blows at a prize-fight are apt to make a refined spectator sick; but his blood is soon up in favor of one party, and it will then seem as if the other fellow could not be banged and pounded and mangled enough--the refined spectator would like to reinforce the blows himself. Over the sinister orgies of blood of certain depraved and insane persons let a curtain be drawn, as well as over the ferocity with which otherwise fairly decent men may be animated, when (at the sacking of a town, for instance), the excitement of victory long delayed, the sudden freedom of rapine and of lust, the contagion of a crowd, and the impulse to imitate and outdo, all combine to swell the blind drunkenness of the killing-instinct, and carry it to its extreme. No! those who try to account for this from above downwards, as if it resulted from the consequences of the victory being rapidly inferred, and from the agreeable sentiments associated with them in the imagination, have missed the root of the matter. Our ferocity is blind, and can only be explained from _below_. Could we trace it back through our line of descent, we should see it taking more and more the form of a fatal reflex response, and at the same time becoming more and more the pure and direct emotion that it is.[376]

In childhood it takes this form. The boys who pull out grasshoppers' legs and butterflies' wings, and disembowel every frog they catch, have no _thought_ at all about the matter. The creatures tempt their hands to a fascinating occupation, to which they have to yield. It is with them as with the 'boy-fiend' Jesse Pomeroy, who cut a little girl's throat, 'just to see how she'd act.' The normal provocatives of the impulse are all living beasts, great and small, toward which a contrary habit has not been formed--all human beings in whom we perceive a certain _intent_ towards _us_, and a large number of human beings who offend us peremptorily, either by their look, or gait, or by some circumstance in their lives which we dislike. Inhibited by sympathy, and by reflection calling up impulses of an opposite kind, civilized men lose the habit of acting out their pugnacious instincts in a perfectly natural way, and a passing feeling of anger, with its comparatively faint bodily expressions, may be the limit of their physical combativeness. Such a feeling as this may, however, be aroused by a wide range of objects. Inanimate things, combinations of color and sound, bad bills of fare, may in persons who combine fastidious taste with an irascible temperament produce real ebullitions of rage. Though the female sex is often said to have less pugnacity than the male, the difference seems connected more with the extent of the motor consequences of the impulse than with its frequency. Women take offence and get angry, if anything, more easily than men, but their anger is inhibited by fear and other principles of their nature from expressing itself in blows. The hunting-instinct proper seems to be decidedly weaker in them than in men. The latter instinct is easily restricted by habit to certain objects, which become legitimate 'game,' while other things are spared. If the hunting-instinct be not exercised at all, it may even entirely die out, and a man may enjoy letting a wild creature live, even though he might easily kill it. Such a type is now becoming frequent; but there is no doubt that in the eyes of a child of nature such a personage would seem a sort of moral monster.

_Fear_ is a reaction aroused by the same objects that arouse ferocity. The antagonism of the two is an interesting study in instinctive dynamics. We both fear, and wish to kill, anything that may kill us; and the question which of the two impulses we shall follow is usually decided by some one of those _collateral circumstances_ of the particular case, to be moved by which is the mark of superior mental natures. Of course this introduces uncertainty into the reaction; but it is an uncertainty found in the higher brutes as well as in men, and ought not to be taken as proof that we are less instinctive than they. Fear has bodily expressions of an extremely energetic kind, and stands, beside lust and anger, as one of the three most exciting emotions of which our nature is susceptible. The progress from brute to man is characterized by nothing so much as by the decrease in frequency of proper occasions for fear. In civilized life, in particular, it has at last become possible for large numbers of people to pass from the cradle to the grave without ever having had a pang of genuine fear. Many of us need an attack of mental disease to teach us the meaning of the word. Hence the possibility of so much blindly optimistic philosophy and religion. The atrocities of life become 'like a tale of little meaning though the words are strong;' we doubt if anything like _us_ ever really was within the tiger's jaws, and conclude that the horrors we hear of are but a sort of painted tapestry for the chambers in which we lie so comfortably at peace with ourselves and with the world.

Be this as it may, fear is a genuine instinct, and one of the earliest shown by the human child. _Noises_ seem especially to call it forth. Most noises from the outer world, to a child bred in the house, have no exact significance. They are simply startling. To quote a good observer, M. Perez:

"Children between three and ten months are less often alarmed by
visual than by auditory impressions. In cats, from the fifteenth
day, the contrary is the case. A child, three and a half months old,
in the midst of the turmoil of a conflagration, in presence of the
devouring flames and ruined walls, showed neither astonishment nor
fear, but smiled at the woman who was taking care of him, while his
parents were busy. The noise, however, of the trumpet of the firemen,
who were approaching, and that of the wheels of the engine, made him
start and cry. At this age I have never yet seen an infant startled
at a flash of lightning, even when intense; but I have seen many of
them alarmed at the voice of the thunder.... Thus fear comes rather
by the ears than by the eyes, to the child without experience. It is
natural that this should be reversed, or reduced, in animals
organized to perceive danger afar. Accordingly, although I have never
seen a child frightened at his first sight of fire, I have many a
time seen young dogs, young cats, young chickens, and young birds
frightened thereby.... I picked up some years ago a lost cat about a
year old. Some months afterward at the onset of cold weather I lit the
fire in the grate of my study, which was her reception-room. She first
looked at the flame in a very frightened way. I brought her near to
it. She leaped away and ran to hide under the bed. Although the fire
was lighted every day, it was not until the end of the winter that I
could prevail upon her to stay upon a chair near it. The next winter,
however, all apprehension had disappeared.... Let us, then, conclude
that there are hereditary dispositions to fear, which are independent
of experience, but which experiences may end by attenuating very
considerably. In the human infant I believe them to be particularly
connected with the ear."[377]

The effect of noise in heightening any terror we may feel in adult years is very marked. The _howling_ of the storm, whether on sea or land, is a principal cause of our anxiety when exposed to it. The writer has been interested in noticing in his own person, while lying in bed, and kept awake by the wind outside, how invariably each loud gust of it arrested momentarily his heart. A dog, attacking us, is much more dreadful by reason of the noises he makes.

_Strange men_, and _strange animals_, either large or small, excite fear, but especially men or animals advancing toward us in a threatening way. This is entirely instinctive and antecedent to experience. Some children will cry with terror at their very first sight of a cat or dog, and it will often be impossible for weeks to make them touch it. Others will wish to fondle it almost immediately. Certain kinds of 'vermin,' especially spiders and snakes, seem to excite a fear unusually difficult to overcome. It is impossible to say how much of this difference is instinctive and how much the result of stories heard about these creatures. That the fear of 'vermin' ripens gradually, seemed to me to be proved in a child of my own to whom I gave a live frog once, at the age of six to eight months, and again when he was a year and a half old. The first time he seized it promptly, and holding it, in spite of its struggling, at last got its head into his mouth. He then let it crawl up his breast, and get upon his face, without showing alarm. But the second time, although he had seen no frog and heard no story about a frog between whiles, it was almost impossible to induce him to touch it. Another child, a year old, eagerly took some very large spiders into his hand. At present he is afraid, but has been exposed meanwhile to the teachings of the nursery. One of my children from her birth upwards saw daily the pet pug-dog of the house, and never betrayed the slightest fear until she was (if I recollect rightly) about eight months old. Then the instinct suddenly seemed to develop, and with such intensity that familiarity had no mitigating effect. She screamed whenever the dog entered the room, and for many months remained afraid to touch him. It is needless to say that no change in the pug's unfailingly friendly conduct had anything to do with this change of feeling in the child.

Preyer tells of a young child screaming with fear on being carried near to the _sea_. The great source of terror to infancy is solitude. The teleology of this is obvious, as is also that of the infant's expression of dismay--the never-failing cry--on waking up and finding himself alone.

_Black things_, and especially _dark places_, holes, caverns, etc., arouse a peculiarly gruesome fear. This fear, as well as that of solitude, of being 'lost,' are explained after a fashion by ancestral experience. Says Schneider:

"It is a fact that men, especially in childhood, fear to go into a
dark cavern or a gloomy wood. This feeling of fear arises, to be sure,
partly from the fact that we easily suspect that dangerous beasts may
lurk in these localities--a suspicion due to stories we have heard and
read. But, on the other hand, it is quite sure that this fear at a
certain perception is also directly inherited. Children who have been
carefully guarded from all ghost-stories are nevertheless terrified
and cry if led into a dark place, especially if sounds are made there.
Even an adult can easily observe that an uncomfortable timidity steals
over him in a lonely wood at night, although he may have the fixed
conviction that not the slightest danger is near.
"This feeling of fear occurs in many men even in their own house after
dark, although it is much stronger in a dark cavern or forest. The
fact of such instinctive fear is easily explicable when we consider
that our savage ancestors through innumerable generations were
accustomed to meet with dangerous beasts in caverns, especially bears,
and were for the most part attacked by such beasts during the night
and in the woods, and that thus an inseparable association between the
perceptions of darkness of caverns and woods, and fear took place, and
was inherited."[378]

_High places_ cause fear of a peculiarly sickening sort, though here, again, individuals differ enormously. The utterly blind instinctive character of the motor impulses here is shown by the fact that they are almost always entirely unreasonable, but that reason is powerless to suppress them. That they are a mere incidental peculiarity of the nervous system, like liability to sea-sickness, or love of music, with no teleological significance, seems more than probable. The fear in question varies so much from one person to another, and its detrimental effects are so much more obvious than its uses, that it is hard to see how it could be a selected instinct. Man is anatomically one of the best fitted of animals for climbing about high places. The best psychical complement to this equipment would seem to be a 'level head' when there, not a dread of going there at all. In fact, the teleology of fear, beyond a certain point, is very dubious. Professor Mosso, in his interesting monograph, 'La Paura' (which has been translated into French), concludes that many of its manifestations must be considered pathological rather than useful; Bain, in several places, expresses the same opinion; and this, I think, is surely the view which any observer without _a priori_ prejudices must take. A certain amount of timidity obviously adapts us to the world we live in, but the _fear-paroxysm_ is surely altogether harmful to him who is its prey.

Fear of the supernatural is one variety of fear. It is difficult to assign any normal object for this fear, unless it were a genuine ghost. But, in spite of psychical research-societies, science has not yet adopted ghosts; so we can only say that certain _ideas_ of supernatural agency, associated with real circumstances, produce a peculiar kind of horror. This horror is probably explicable as the result of a combination of simpler horrors. To bring the ghostly terror to its maximum, many usual elements of the dreadful must combine, such as loneliness, darkness, inexplicable sounds, especially of a dismal character, moving figures half discerned (or, if discerned, of dreadful aspect), and a vertiginous baffling of the expectation. This last element, which is _intellectual_, is very important. It produces a strange emotional 'curdle' in our blood to see a process with which we are familiar deliberately taking an unwonted course. Any one's heart would stop beating if he perceived his chair sliding unassisted across the floor. The lower animals appear to be sensitive to the mysteriously exceptional as well as ourselves. My friend Professor W. K. Brooks, of the Johns Hopkins University, told me of his large and noble dog being frightened into a sort of epileptic fit by a bone being drawn across the floor by a thread which the dog did not see. Darwin and Romanes have given similar experiences.[379] The idea of the supernatural involves that the usual should be set at naught. In the witch and hobgoblin supernatural, other elements still of fear are brought in--caverns, slime and ooze, vermin, corpses, and the like.[380] A human corpse seems normally to produce an instinctive dread, which is no doubt somewhat due to its mysteriousness, and which familiarity rapidly dispels. But, in view of the fact that cadaveric, reptilian, and underground horrors play so specific and constant a part in many nightmares and forms of delirium, it seems not altogether unwise to ask whether these forms of dreadful circumstance may not at a former period have been more normal objects of the environment than now. The ordinary cock-sure evolutionist ought to have no difficulty in explaining these terrors, and the scenery that provokes them, as relapses into the consciousness of the cave-men, a consciousness usually overlaid in us by experiences of more recent date.

There are certain other pathological fears, and certain peculiarities in the expression of ordinary fear, which might receive an explanatory light from ancestral conditions, even infra-human ones. In ordinary fear, one may either run, or remain semi-paralyzed. The latter condition reminds us of the so-called death-shamming instinct shown by many animals. Dr. Lindsay, in his work 'Mind in Animals,' says this must require great self-command in those that practise it. But it is really no feigning of death at all, and requires no self-command. It is simply a terror-paralysis which has been so useful as to become hereditary. The beast of prey does not think the motionless bird, insect, or crustacean dead. He simply fails to notice them at all; because his senses, like ours, are much more strongly excited by a moving obje