The essence of English idealism is to regard extensity as a property of tactile perceptions. As it sees nothing in sensible qualities but sen sations, and in sensations themselves nothing but mental states, it finds in the different qualities CHAP, rv EXTENSITY AND EXTENSION 283 nothing on which to base the parallelism of idealism and their phenomena. It is therefore con- regard the strained to account for this parallelism orders of by a habit which makes the actual persensation as...,.
discontinuous, ceptions of sight, lor instance, suggest and so miss ~. 0<:> the true to us potential sensations of touch. If nature of.,.. „ perception, the impressions of two different senses resemble each other no more than the words of two languages, we shall seek in vain to de duce the data of the one from the data of the other. They have no common element; and consequently, there is nothing common between extensity, which is always tactile, and the data of the senses other than that of touch, which must then be supposed to be in no way extended. But neither can atomistic realism, which locates movements in space and sensations in conscious ness, discover anything in common between the modifications or phenomena of extensity and the sensations which correspond to them. Sensations are supposed to issue from the modifications as a kind of phosphorescence, or, again, to translate into the language of the soul the manifestations of matter; but in neither case do they re flect, we are told, the image of their causes. No doubt they may all be traced to a common origin, which is movement in space; but, just because they develop outside of space, they must forego, qua sensations, the kinship which binds their causes together. In breaking with space they break also their connexion with each other; they 284 MATTER AND MEMORY CHAP, nr have nothing in common between them, nor with extensity.
Idealism and realism, then, only differ in that the first relegates extensity to tactile perception, of which it becomes the exclusive property, while the second thrusts extensity yet further back, outside of all perception. But the two doctrines are agreed in maintaining the discon tinuity of the different orders of sensible qualities, and also the abrupt transition from that which is purely extended to that which is not extended at all. Now the principal difficulties which they both encounter in the theory of perception arise from this common postulate.
For suppose, to begin with, as Berkeley did, that all perception of extensity is to be referred to the sense of touch. We may, indeed, if you will have it so, deny extension to the data of hearing, smell and taste; but we must at least explain the genesis of a visual space that corre sponds to tactile space. It is alleged, indeed, that sight ends by becoming symbolic of touch, and that there is nothing more in the visual per ception of the order of things in space than a suggestion of tactile perception. But we fail to understand how the visual perception of relief, for instance, a perception which makes upon us an impress sui generis, and indeed indescribable, could ever be one with the mere remembrance of a sensation of touch. The association of a mem ory with a present perception may complicate CHAP, iv EXTENSITY AND EXTENSION 285 this perception by enriching it with an element already known, but it cannot create a new kind of impress, a new quality of perception: now the visual perception of relief presents an abso lutely original character. It may be urged that it is possible to give the illusion of relief with a plane surface. This only proves that a surface, on which the play of light and shadow on an object in relief is more or less well imitated, is enough to remind us of relief; but how could we be reminded of relief if relief had not been, at first, actually perceived? We have already said, but we cannot repeat too often, that our theories of perception are entirely vitiated by the idea that if a certain arrangement produces, at a given moment, the illusion of a certain perception, it must always have been able to produce the perception itself; — as if the very- function of memory were not to make the complexity of the effect survive the simplifica tion of the cause! Again, it may be urged that the retina itself is a plane surface, and that if we perceive by sight something that is extended, it can only be the image on the retina. But is it not true, as we have shown at the beginning of this book, that in the visual perception of an object the brain, nerves, retina and the object itself form a connected whole, a continuous process in which the image on the retina is only an episode? By what right, then, do we isolate this image to sum up in it the whole of percep- 286 MATTER AND MEMORY CHAP, iv tion? And then, as we have also shown,1 how could a surface be perceived as a surface otherwise than,in a space that has recovered its three dimensions? Berkeley, at least, carried out his theory to its conclusion; he denied to sight any perception of extensity. But the ob jections which we raised only acquire the more force from this, since it is impossible to understand the spontaneous creation, by a mere association of memories, of all that is original in our visual perceptions of line, surface and volume, per ceptions so distinct that the mathematician does not go beyond them and works with a space that is purely visual. But we will not insist on these various points, nor on the disputable argu ments drawn from the observation of those, born blind, whose sight has been surgically restored: the theory of the acquired perceptions of sight, classical since Berkeley's day, does not seem likely to resist the multiplied attacks of contemporary psychology.2 Passing over the difficulties of a psychological order, we will content ourselves with drawing attention to another point, in our opinion essential. Suppose for a moment that 1 Time and Free Will. Sonnenschein & Co., 1910.
8 See on this subject: Paul Janet, La perception visuelle de la distance, Revue philosophique, 1879, vol. vii, p. I et seq. — William James, Principles of Psychology, vol.ii, chap. xxii. — Cf. on the subject of the visual perception of extensity: Dunan, L'espace visuel et I'espace tactile (Revue philosophique, Feb. and Apr. 1888, Jan. 1889).
CHAP iv. EXTENSITY AND EXTENSION 287 the eye does not, at the outset, give us any informa tion as to any of the relations of space. Visual form, visual relief, visual distance, then become the symbols of tactile perceptions. But how is it, then, that this symbolism succeeds? Here are objects which change their shape and move. Vision takes note of definite changes which touch afterwards verifies. There is, then, in the two series, visual and tactile, or in their causes, something which makes them correspond one to another and ensures the constancy of their parallelism. What is the principle of this con nexion?
For English idealism, it can only be some deus ex machina, and we are confronted with a mys tery again. For ordinary realism, it is in a space distinct from the sensations themselves that the principle of the correspondence of sensations one with another lies; but this doctrine only throws the difficulty further back and even aggravates it, for we shall now want to know how a system of homogeneous movements in space evokes various sensations which have no resemblance whatever with them. Just now the genesis of visual perception of space by a mere association of images appeared to us to imply a real creation ex nihilo; here all the sen sations are born of nothing, or at least have no resemblance with the movement that occasions them. In the main, this second theory differs much less from the first than is commonly believed.
288 MATTER AND MEMORY CHAP, iv Amorphous space, atoms jostling against each other, are only our tactile perceptions made ob jective, set apart from all our other perceptions on account of the special importance which we attribute to them, and made into independent realities, — thus contrasting with the other sensa tions which are then supposed to be only the symbols of these. Indeed, in the course of this operation, we have emptied these tactile sensa tions of a part of their content; after having reduced all other senses to being mere appen dages of the sense of touch, touch itself we mu tilate, leaving out everything in it that is not a mere abstract or diagrammatic design of tac tile perception: with this design we then go on to construct the external world. Can we wonder that between this abstraction on the one hand, and sensations on the other, no possible link is to be found? But the truth is that space is no more without us than within us, and that it does not belong to a privileged group of sensations. All sensations partake of extensity; all are more or less deeply rooted in it; and the difficulties of ordinary realism arise from the fact that, the kinship of the sensations one with another having been extracted and placed apart under the form of an indefinite and empty space, we no longer see either how these sensations can partake of extensity or how they can corre spond with each other.
Contemporary psychology is more and more CHAP, iv EXTENSITY AND EXTENSION 289 impressed with the idea that all our sensations But modem are in some degree extensive. It is psychology..,., has a tendency maintained, not without an appearance to regard all.,.
sensation as of reason, that there is no sensation extensive. without cxtensity l or without a feel ing 'of volume.' 2 English idealism sought to reserve to tactile perception a monopoly of the extended, the other senses dealing with space only in so far as they remind us of the data of touch. A more attentive psychology reveals to us, on the contrary, and no doubt will hereafter reveal still more clearly, the need of regarding all sensa tions as primarily extensive, their extensity fading and disappearing before the higher intensity and usefulness of tactile, and also, no doubt, of visual, extensity.
So understood, space is indeed the symbol of fixity and of infinite divisibility. Concrete we invert extensity, that is to say the diversity of wewlaSSst sensible qualities, is not within space; interior*"! rather is it space that we thrust into S°?he'neoe£ extensity. Space is not a ground on which St totece" real motion is posited; rather is it real movements. motiOn that deposits space beneath it self. But our imagination, which is preoccu- 1 Ward, Article Psychology in the Encycl. Britannica.
2 W. James, Principles of Psychology, vol. ii, p. 134 et seq. — We may note in passing that we might, in strictness, attribute this opinion to Kant, since The Transcendental /Esthetic allows no difference between the data of the different senses as far as their extension in space is concerned. But it must not be forgotten that the point of view of the Critique is other than u 29O MATTER AND MEMORY CHAP, iv pied above all by the convenience of expression and the exigencies of material life, prefers to invert the natural order of the terms. Accus tomed to seek its fulcrum in a world of ready- made motionless images, of which the apparent fixity is hardly anything else but the outward reflexion of the stability of our lower needs, it cannot help believing that rest is anterior to motion, cannot avoid taking rest as its point of reference and its abiding place, so that it comes to see movement as only a variation of distance, space being thus supposed to precede motion. Then, in a space which is homo geneous and infinitely divisible, we draw, in imagination, a trajectory and fix positions: after wards, applying the movement to the trajectory, we see it divisible like the line we have drawn, and equally denuded of quality. Can we wonder that our understanding, working thenceforward on this idea, which represents precisely the reverse of the truth, discovers in it nothing but contra dictions? Having assimilated movements to space, we find these movements homogeneous like space; and since we no longer see in them anything but calculable differences of direction and velocity, all relation between movement and quality is for us destroyed. So that all we have to do is to shut up motion in space, qualities in consciousness, and that of psychology, and that it is enough for its purpose that all our sensations should end by being localized in space when perception has reached its final form.
CHAP, iv EXTENSITY AND EXTENSION to establish between these two parallel series, incapable, by hypothesis, of ever meeting, a mysterious correspondence. Thrown back into consciousness, sensible qualities become incap able of recovering extensity., Relegated to space, and indeed to abstract space, where there is never but a single instant and where everything is always being born anew — movement aban dons that solidarity of the present with the past which is its very essence. And as these two aspects of perception, quality and movement, have been made equally obscure, the phenomenon of perception, in which a consciousness, assumed to be shut up in itself and foreign to space, is supposed to translate what occurs in space, be comes a mystery. — But let us, on the contrary, banish all preconceived idea of interpreting or measuring, let us place ourselves face to face with immediate reality: at once we find that there is no impassable barrier, no essential differ ence, no real distinction even, between percep tion and the thing perceived, between quality and movement.
So we return, by a round-about way, to the conclusions worked out in the first chapter of this book. Our perception, we said, is originally in things rather than in the mind, without us rather than within. The several kinds of percep tion correspond to so many directions actually marked out in reality. But, we added, this theTr MATTER AND MEMORY CHAP, iv perception, which coincides with its object, exists rather in theory than in fact: it could only happen if we were shut up within the present moment. In concrete perception memory inter venes, and the subjectivity of sensible qualities is due precisely to the fact that our consciousness, which begins by being only memory, prolongs a plurality of moments into each other, contract ing them into a single intuition.
Consciousness and matter, body and soul, were thus seen to meet each other in perception. But Perception m one asPect this idea remained for us obscure, because our perception, and con- sequently also our consciousness, seemed of tnus to snare m the divisibility which is action. attributed to matter. If, on the dualis- tic hypothesis, we naturally shrink from accepting the partial coincidence of the perceived object and the perceiving subject, it is because we are conscious of the undivided unity of our percep tion, whereas the object appears to us to be, in essence, infinitely divisible. Hence the hypo thesis of a consciousness with inextensive sensa tions, placed over against an extended multiplicity. But if the divisibility of matter is entirely relative to our action thereon, that is to say to our faculty of modifying its aspect, if it belongs not to matter itself but to the space which we throw beneath this matter in order to bring it within our grasp, then the difficulty disappears. Ex tended matter, regarded as a whole, is like a CHAP, iv SOUL AND BODY consciousness where everything balances and compensates and neutralizes everything else; it possesses in very truth the indivisibility of our perception; so that, inversely, we may without scruple attribute to perception something of the extensity of matter. These two terms, perception and matter, approach each other in the measure that we divest ourselves of what may be called the prejudices of action: sensation recovers ex- tensity, the concrete extended recovers its natural continuity and indivisibility.. And homogeneous space, which stood between the two terms like an insurmountable barrier, is then seen to have no other reality than that of a diagram or a symbol. It interests the behaviour of a being which acts upon matter, but not the work of a mind which specu lates on its essence.
Thereby also some light may be thrown upon the problem towards which all our en- ordinary quiries converge, that of the union of body and soul. The obscurity of this problem, on the dualistic hypothesis, comes from the double fact that matter is considered as essentially divisible and every state of the soul as rigorously in- thcm. extensive, so that from the outset the communication between the two terms is severed. And when we go more deeply into this double postulate, we discover, in regard to matter, a confusion of concrete and indivisible extensity with the divisible space which underlies it; and 294 MATTER AND MEMORY CHAP, iv also, in regard to mind, the illusory idea that there are no degrees, no possible transition, between the extended and the unextended. But if these two postulates involve a common error, if there is a gradual passage from the idea to the image and from the image to the sensation; if, in the measure in which it evolves towards actuality, that is to say towards action, the mental state draws nearer to extension; if, finally, this extension once attained remains undivided and therefore is not out of harmony with the unity of the soul; we can understand that spirit can rest upon matter and consequently unite with it in the act of pure perception, yet nevertheless be radically distinct from it. It is distinct from matter in that it is, even then, memory, that is to say a synthesis of past and present with a view to the future, in that it contracts the moments of this matter in order to use them and to manifest itself by actions which are the final aim of its union with the body. We were right, then, when we said, at the beginning of this book, that the distinction between body and mind must be estab lished in terms not of space but of time.
The mistake of ordinary dualism is that it starts from the spatial point of view: it puts on the one hand matter with its modifications in space, on the other unextended sensations in con sciousness. Hence the impossibility of under standing how the spirit acts upon the body or the body upon spirit. Hence hypotheses which are CHAP, iv SOUL AND BODY andean be nothing but disguised statements of the fact, — the idea of a parallelism or of a pre-estab lished harmony. But hence also the impossibility of constituting either a psychology of memory or a metaphysic of matter. We have striven to show that this psychology and this metaphysic are bound up with each other, and that the difficul ties are less formidable in a dualism which, starting from pure perception, where subject and object coincide, follows the development of the two terms in their respective durations, — matter, the further we push its analysis, tending more and more to be only a succession of infinitely rapid moments which may be deduced each from the other and thereby are equivalent to each other • spirit being in perception already memory, and declaring itself more and more as a prolonging of the past into the present, a progress, a true evolution.
But does the relation of body and mind become thereby clearer? We substitute a temporal for But the dis- a spatial distinction: are the two terms tween m£d anY the more able to unite? It must be ™oumabteer observed that the first distinction does ™ofoei S^eT not admit of degree: matter is supposed to be in space, spirit to be extra- spatial; there is no possible transition degrees. between them. But if, in fact, the humblest function of spirit is to bind together the successive moments of the duration of things, if it is by this that it comes into con tact with matter and by this also that it is first 296 MATTER AND MEMORY CHAP, iv of all distinguished from matter, we can con ceive an infinite number of degrees between matter and fully developed spirit — a spirit capable of action which is not only undetermined, but also reasonable and reflective. Each of these suc cessive degrees, which measures a growing inten sity of life, corresponds to a higher tension of dura tion and is made manifest externally by a greater development of the sensori-motor system. But let us consider this nervous system itself: we note that its increasing complexity appears to allow an ever greater latitude to the activity of the living being, the faculty of waiting before reacting, and of putting the excitation received into relation with an ever richer variety of motor mechanisms. Yet this is only the outward aspect; and the more complex organization of the nervous system, which seems to assure the greater independence of the living being in regard to matter, is only the material symbol of that independence itself, that is to say of the inner energy which allows the being to free itself from the rhythm of the flow of things, and to retain in an ever higher degree the past in order to influence ever more deeply the future, — the symbol, in the special sense which we give to the word, of its memory. Thus, between brute matter and the mind most cap able of reflexion there are all possible intensities of memory or, what comes to the same thing, all the degrees of freedom. On the first hypo thesis, that which expresses the distinction be- CHAF. iv SOUL AND BODY tween spirit and body in terms of space, body and spirit are like two railway lines which cut each other at a right angle; on the second, the rails come together in a curve, so that we pass insensibly from the one to the other.
But have we here anything but a metaphor? Does not a marked distinction, an irreducible oppo sition, remain between matter properly so-called and the lowest degree of freedom or of memory? Yes, no doubt, the distinction subsists, but union becomes possible, since it would be given, under the radical form of a partial coincidence, in pure perception. The difficulties of ordinary dualism come, not from the distinction of the two terms, but from the impossibility of seeing how the one is grafted upon the other. Now, as we have shown, pure perception, which is the lowest degree of mind, — mind without memory — is really part of matter, as we understand matter. We may go further: memory does not intervene as a func tion of which matter has no presentiment and which it does not imitate in its own way. If matter does not remember the past, it is because it repeats the past unceasingly, because, subject to necessity, it unfolds a series of moments of which each is the equivalent of the preceding moment and may be deduced from it: thus its past is truly given in its present. But a being which evolves more or less freely creates something new every moment: in vain, then, should we seek to read its past in its present 298 MATTER AND MEMORY CHAP, iv unless its past were deposited within it in the form of memory. Thus, to use again a metaphor which has more than once appeared in this book, it is necessary, and for similar reasons, that the past should be acted by matter, imagined by mind.
SUMMARY AND CONCLUSION I. THE idea that we have disengaged from the facts and confirmed by reasoning is that our body The body an *s an instrument of action, and of action SsSo£nt omv- I*1 no degree, in no sense, under only- no aspect, does it serve to prepare, far less to explain, a representation. Consider ex ternal perception: there is only a difference of degree, not of kind, between the so-called percep tive faculties of the brain and the reflex functions of the spinal cord. While the spinal cord trans forms the excitations received into movements which are more or less necessarily executed, the brain puts them into relation with motor mechan isms which are more or less freely chosen; but that which the brain explains in our perception is action begun, prepared or suggested, it is not perception itself. Consider memory, the body retains motor habits capable of acting the past over again; it can resume attitudes in which the past will insert itself; or, again, by the repeti tion of certain cerebral phenomena which have prolonged former perceptions, it can furnish to remembrance a point of attachment with the actual, a means of recovering its lost influence upon present reality: but in no case can the brain 280 3<X> MATTER AND MEMORY store up recollections or images. Thus, neither in perception, nor in memory, nor a fortiori in the higher attainments of mind, does the body con tribute directly to representation. By develop ing this hypothesis under its manifold aspects and thus pushing dualism to an extreme, we appeared to divide body and soul by an impassable abyss. In truth, we were indicating the only possible means of bringing them together.