necessary action will take place automatically, when its hour strikes. But I have supposed that the office of the image which I call my body was to exercise on other images a real influence, and, consequently, to decide which step to take among several which are all materially possible. And since these steps are probably suggested to it by the greater or less advantage which it can derive from the surrounding images, these images must display in some way, upon the aspect which they present to my body, the profit which my body can gain from them. In fact, I note that the size, shape, even the colour, of external objects is modified according as my body approaches or recedes from them; that the strength of an odour, the intensity of a sound, increases or di minishes with distance; finally, that this very distance represents, above all, the measure in which surrounding bodies are insured, in some sort, against the immediate action of my body. In the degree that my horizon widens, the images which surround me seem to be painted upon a more uniform background and become to me more indifferent. The more I narrow this horizon, the more the objects which it circumscribes space themselves out distinctly according to the greater or less ease with which my body can touch and move them. They send back, then, to my body, as would a mirror, its eventual influence; they take rank in an order corresponding to the growing or decreasing powers of my body. The CHAP, i REAL AND VIRTUAL ACTION 7 objects which surround my body reflect its possible action upon them.
I will now, without touching the other images, modify slightly that image which I call my body.
In this image I cut asunder, in thought, point to all the afferent nerves of the cerebrot!l6S6 possible spinal system. What will happen? A few cuts with the scalpel have severed a few bundles of fibres: the rest of the universe, and even the rest of my body, remain what they were before. The change effected is therefore insignificant. As a matter of fact, my perception has entirely vanished. Let us con sider more closely what has just occurred. Here are the images which compose the universe in general, then those which are near to my body, and finally my body itself. In this last image the habitual office of the centripetal nerves is to transmit movements to the brain and to the cord; the centrifugal nerves send back this movement to the periphery. Section of the centripetal nerves can therefore produce only one intelligible effect; that is, to interrupt the current which goes from the periphery to the periphery by way of the centre, and, conse quently, to make it impossible for my body to extract, from among all the things which surround it, the quantity and quality of movement neces sary in order to act upon them. Here is some thing which concerns action, and action alone.
Yet it is my perception which has vanished. What does this mean, if not that my perception displays, in the midst of the image world, as would their outward reflexion or shadow, the eventual or possible actions of my body? Now the system of images in which the scalpel has effected only an insignificant change is what is generally called the material world; and, on the other hand, that which has just vanished is ' my perception ' of matter. Whence, provisionally, these two definitions: / call matter the aggregate of images, and perception of matter these same images referred to the eventual action of one particular image, my body.
Let us go more deeply into this reference. I consider my body, with its centripetal and cen-The brain IB trifugal nerves, with its nerve centres. w°i"hemotor ^ know that external objects make in SSth^onsSoM t^6 afferent nerves a disturbance which perception, passes onward to the centres, that the centres are the theatre of very varied molecular movements, and that these movements depend on the nature and position of the objects. Change the objects, or modify their relation to my body, and everything is changed in the interior move ments of my perceptive centres. But every thing is also changed in 'my perception.' My perception is, then, a function of these molecular movements; it depends upon them. But how does it depend upon them? It will perhaps be CHAP, i REPRESENTATION 9 said that it translates them, and that, in the main, I represent to myself nothing but the molecular movements of cerebral substance. But how should this have any meaning, since the image of the nervous system and of its internal movements is only, by hypothesis, that of a cer tain material object, whereas I represent to myself the whole material universe? It is true that many philosophers attempt to evade the diffi culty. They show us a brain, analogous in its essence to the rest of the material universe, an image, consequently, if the universe is an image. Then, since they want the internal move ments of this brain to create or determine the representation of the whole material world — an image infinitely greater than that of the cere bral vibrations— they maintain that these mole cular movements, and movement in general, are not images like others, but something which is either more or less than an image — in any case is of another nature than an image — and from which representation will issue as by miracle. Thus matter is made into something radically different from representation, something of which, consequently, we have no image; over against it they place a consciousness empty of images, of which we are unable to form any idea; lastly, to fill consciousness, they invent an incom prehensible action of this formless matter upon this matterless thought. But the truth is that the movements of matter are very clear, regarded as images, and that there is no need to look in movement for anything more than what we see in it. The sole difficulty would consist in bring ing forth from these very particular images the infinite variety of representations; but why seek to do so, since we all agree that the cerebral vibrations are contained in the material world, and that these images, consequently, are only a part of the representation? — What then are these movements, and what part do these particular images play in the representation of the whole? The answer is obvious: they are, within my body, the movements intended to prepare, while beginning it, the reaction of my body to the action of external objects. Images themselves, they cannot create images; but they indicate at each moment, like a compass that is being moved about, the position of a certain given image, my body, in relation to the surrounding images. In the totality of representation they are very little; but they are of capital importance for that part of representation which I call my body, since they foreshadow at each successive moment its virtual acts. There is then only a difference of degree — there can be no difference in kind — between what is called the perceptive faculty of the brain and the reflex functions.of the spinal cord. The cord transforms into move ments the stimulation received; the brain prolongs it into reactions which are merely nascent; but, in the one case as in the other, the function CHAP. 1 REPRESENTATION 11 of the nerve substance is to conduct, to coordin ate or to inhibit movements. How then does it come about that ' my perception of the universe ' appears to depend upon the internal movements of the cerebral substance, to change when they vary, and to vanish when they cease?
The difficulty of this problem is mainly due to the fact that the grey matter and its modifications The brain are regarded as things which are suffioannot'cfeSe" cient to themselves and might be isolated images. from the rest of the universe. Materia lists and dualists are fundamentally agreed on this point. They consider certain molecular move ments of the cerebral matter apart: then, some see in our conscious perception a phosphorescence which follows these movements and illuminates their track; for others, our perceptions succeed each other like an unwinding scroll in a conscious ness which expresses continuously, in its own way, the molecular vibrations of the cortical sub stance: in the one case, as in the other, our per ception is supposed to translate or to picture the states of our nervous system. But is it possible to conceive the nervous system as living apart from the organism which nourishes it, from the atmosphere in which the organism breathes, from the earth which that atmosphere envelopes, from the sun round which the earth revolves? More generally, does not the fiction of an isolated material object imply a kind of absurdity, since this object borrows its physical properties from the relations which it maintains with all others, and owes each of its determinations, and conse quently its very existence, to the place which it occupies in the universe as a whole? Let us no longer say, then,that our perceptions depend simply upon the molecular movements of the cerebral mass. We must say rather that they vary with them, but that these movements themselves remain inseparably bound up with the rest of the material world. The question, then, is not only how our perceptions are connected with the modifications of the grey matter. The problem widens, and can also be put in much clearer terms. It might be stated as follows: Here is a system of images which I term my perception of the universe, and which may be entirely images altered by a very slight change in fwo^stems, a cei"tain privileged image, — my body. tS c2SSou£d This image occupies the centre; by it ness. ai} t^ others are conditioned; at each of its movements everything changes, as though by a turn of a kaleidoscope. Here, on the other hand, are the same images, but referred each one to itself; influencing each other no doubt, but in such a manner that the effect is always in pro portion to the cause: this is what I term the universe. The question is: how can these two systems co-exist, and why are the same images relatively invariable in the universe, and infinitely variable in perception? The problem at issue between realism and idealism, perhaps even be- CHAP. I REPRESENTATION 13 tween materialism and spiritualism, should be stated, then, it seems to us, in the following terms: How is it that the same images can belong at the same time to two different systems, the one in which each image varies for itself and in the welldefined measure that it is patient of the real action of surrounding images, the other in which all change for a single image, and in the varying measure that they reflect the eventual action of this privileged image?
Every image is within certain images and with out others; but of the aggregate of images we cannot say that it is within us or without us, since interiority and exteriority are only relations among images. To ask whether the universe exists only in our thought, or outside of our thought, is to put the problem in terms that are insoluble, even if we suppose them to be intelli gible; it is to condemn ourselves to a barren discussion, in which the terms thought, being, universe, will always be taken on either hand in entirely different senses. To settle the matter, we must first find a common ground on which combatants may meet; and since on both sides it is agreed that we can only grasp things in the form of images, we must state the problem in terms of images, and of images alone. Now no philosophical doctrine denies that the same images can enter at the same time into two dis tinct systems, one belonging to science, wherein each image, related only to itself, possesses an absolute value; and the other, the world of con sciousness, wherein all the images depend on a central image, our body, the variations of which they follow. The question raised between realism and idealism then becomes quite clear: what are the relations which these two systems of images maintain with each other? And it is easy to see that subjective idealism consists in deriving the first system from the second, materialistic realism in deriving the second from the first.
The realist starts, in fact, from the universe, that is to say from an aggregate of images gov erned, as to their mutual relations, by realism nor fixed laws, in which effects are in strict able to proportion to their causes, and of which there are two the character is an absence of centre, all the images unfolding on one and the same plane indefinitely prolonged. But he is at once bound to recognize that, besides this system, there are perceptions, that is to say, systems in which these same images seem to depend on a single one among them, around which they range them selves on different planes, so as to be wholly transformed by the slightest modification of this central image. Now this perception is just what the idealist starts from: in the system of images which he adopts there is a privileged image, )ris body, by which the other images are conditioned. But as soon as he attempts to connect the present with the past and to foretell the future, he is obliged to abandon this central position, to replace CHAP, i REALISM AND IDEALISM 15 all the images on the same plane, to suppose that they no longer vary for him, but for themselves; and to treat them as though they made part of a system in which every change gives the exact measure of its cause. On this condition alone a science of the universe becomes possible; and, since this science exists, since it succeeds in fore seeing the future, its fundamental hypothesis can not be arbitrary. The first system alone is given to present experience; but we believe in the second, if only because we affirm the continuity of the past, present, and future. Thus in idealism, as in realism, we posit one of the two systems and seek to deduce the other from it.
But in this deduction neither realism nor ideal ism can succeed, because neither of the two systems of images is implied in the other, and each of them is sufficient to itself. If you posit the system of images which has no centre, and in which each element possesses its absolute dimensions and value, I see no reason why to this system should accrue a second, in which each image has an undetermined value, subject to all the vicissi tudes of a central image. You must then, to engender perception, conjure up some deus ex machina, such as the materialistic hypothesis of the epiphenomenal consciousness, whereby you choose, among all the images that vary absolutely and that you posited to begin with, the one which we term our brain, --conferring on the internal states of this image the singular and inexplicable l6 MATTER AND MEMORY CHAP. I privilege of adding to itself a reproduction, this time relative and variable, of all the others. It is true that you afterwards pretend to attach no importance to this representation, to see in it a mere phosphorescence which the cerebral vibrations leave behind them: as if the cerebral matter and cerebral vibrations, set in the images which com pose this representation, could be of another nature than they! All realism is thus bound to make per ception an accident, and consequently a mystery. But, inversely, if you posit a system of unstable images disposed about a privileged centre, and profoundly modified by trifling displacements of this centre, you begin by excluding the order of nature, that order which is indifferent to the point at which we take our stand and to the particular end from which we begin. You will have to bring back this order by conjuring up in your turn a deus ex machina; I mean that you will have to assume, by an arbitrary hypothesis, some sort of pre-established harmony between things and mind, or, at least (to use Kant's terms), between sense and understanding. It is science now that will become an accident, and its success a mys tery. — You cannot, then, deduce the first system of images from the second, nor the second from the first; and these two antagonistic doctrines, realism and idealism, as soon as they decide to enter the same lists, hurl themselves from opposite directions against the same obstacle.
If we now look closely at the two doctrines, CHAP, i REALISM AND IDEALISM 17 we shall discover in them a common postulate, which we may formulate thus: perboth imply an cefition has a wholly speculative interest; erroneous.., _...,,.
postulate, it is pure knowledge. The whole disviz.,that. * J • perception cussion turns upon the importance to be has merely a.,, *,,, speculative attnbuted to this knowledge as com pared with scientific knowledge. The one doctrine starts from the order required by science, and sees in perception only a confused and provisional science. The other puts perception in the first place, erects it into an absolute, and then holds science to be a symbolic expression of the real. But, for both parties, to perceive means above all to know.
Now it is just this postulate that we dispute. Even the most superficial examination of the structure of the nervous system in the animal series gives it the lie. And it is not possible to accept it without profoundly obscuring the threefold problem of matter, consciousness, and their relation.
For if we follow, step by step, the progress of external perception from the monera to the higher vertebrates, we find that living matter, But facts.
reaiiy suggest even as a simple mass of protoplasm, is the opposite,,..,,,., view. already irritable and contractile, that Evidence bom the it is open to the influence of external structure and.
evolution of stimulation, and answers to it by mechanical, physical, and chemical re actions. As we rise in the organic series, we find a division of physiological labour. Nerve cells l8 MATTER AND MEMORY CHAP. I appear, are diversified, tend to group themselves into a system; at the same time, the animal reacts by more varied movements to external stimulation. But even when the stimulation re ceived is not at once prolonged into movement, it appears merely to await its occasion; and the same impression, which makes the organism aware of changes in the environment, determines it or pre pares it to adapt itself to them. No doubt there is in the higher vertebrates a radical distinction between pure automatism, of which the seat is mainly in the spinal cord, and voluntary activity, which requires the intervention of the brain. It might be imagined that the impression received, instead of expanding into more movements, spiritualizes itself into consciousness. But as soon as we compare the structure of the spinal cord with that of the brain, we are bound to infer that there is merely a difference of complication, and not a difference in kind, between the functions of the brain and the reflex activity of the medullary system. For what takes place in reflex action? The centripetal movement communicated by the stimulus is reflected at once, by the intermediary of the nerve centres of the spinal cord, in a centrifugal movement determining a muscular contraction.
In what, on the other hand, does the function of the cerebral system consist? The peripheral excita tion, instead of proceeding directly to the motorcells of the spinal cord and impressing on the muscle a necessary contraction, mounts first to the brain, and then descends again to the very same motor cells of the spinal cord which intervened in the reflex action. Now what has it gained by this round about course, and what did it seek in the so-called sensory cells of the cerebral cortex? I do not un derstand, I shall never understand, that it draws thence a miraculous power of changing itself into a representation of things; and moreover, I hold this hypothesis to be useless, as will shortly ap pear. But what I do see clearly is that the cells of the various regions of the cortex which are termed sensory, — cells interposed between the terminal branches of the centripetal fibres and the motor cells of the Rolandic area, — allow the stimulation received to reach at will this or that motor mechan ism of the spinal cord, and so to choose its effect. The more these intercalated cells are multiplied and the more they project amoeboid prolonga tions which are probably capable of approaching each other in various ways, the more numerous and more varied will be the paths capable of opening to one and the same disturbance from the periphery, and, consequently, the more systems of movements will there be among which one and the same stimulation will allow of choice. In our opinion, then, the brain is no more than a kind of central telephonic exchange: its office is to allow communication, or to delay it. It adds nothing to what it receives; but, as all the organs of perception send it to their ultimate prolongations, and as all the motor mechanisms of the spinal cord and of the medulla oblongata have in it their accredited representatives, it really constitutes a centre, where the peripheral excitation gets into relation with this or that motor mechanism, chosen and no longer prescribed. On the other hand, as a great multitude of motor tracks can open simul taneously in this substance to one and the same excitation from the periphery, this disturbance may subdivide to any extent, and consequently dissipate itself in innumerable motor reactions which are merely nascent. Hence the office of the brain is sometimes to conduct the movement received to a chosen organ of reaction, and sometimes to open to this movement the totality of the motor tracks, so that it may manifest there all the potential reactions with which it is charged, and may divide and so disperse. In other words, the brain appears to us to be an instrument of analysis in regard to the movement received, and an instrument of selec tion in regard to the movement executed. But, in the one case as in the other, its office is limited to the transmission and division of movement. And no more in the higher centres of the cortex than in the spinal cord do the nervous elements work with a view to knowledge: they do but indicate a number of possible actions at once, or organize one of them.
That is to say that the nervous system is in no sense an apparatus which may serve to fabricate, or even to prepare, representations. Its function is to receive stimulation, to pro vide motor apparatus, and to present the largest possible number of these apparatuses to a given stimulus. The more it develops, the more numerous and the more distant are the points of space which it brings into relation with ever more complex motor mechan isms. In this way the scope which it allows to our action enlarges: its growing perfection consists in nothing else. But if the nervous system is thus constructed, from one end of the animal series to the other, in view of an action which is less and less necessary, must we not think that perception, of which the progress is regulated by that of the nervous system, is also entirely directed towards action, and not towards pure knowledge? And, if this be so, is not the growing richness of this perception likely to symbolize the wider range of indetermination left to the choice of the living being in its conduct with regard to things? Let us start, then, from this indetermination as from the true principle, and try whether we cannot deduce from it the possibility, and even the necessity, of conscious perception. In other words, let us posit that system of closely-linked images which we call the material world, and imagine here and there, within the system, centres of real action, represented by living matter: what we mean to prove is that there must be, ranged round each one of these centres, images that are subordinated to its posi tion and variable with it; that conscious percep tion is bound to occur, and that, moreover, it is possible to understand how it arises.
We note, in the first place, that a strict law con nects the amount of conscious perception with the intensity of action at the disposal of the st°ar7efr?msthe living being. If our hypothesis is well founded, this perception appears at the precise moment when a stimulation received by matter is not prolonged into a necessary action. In the case of a rudi mentary organism, it is true that immediate contact with the object which interests it is necessary to pro duce the stimulation, and that reaction can then hardly be delayed. Thus, in the lower organ isms, touch is active and passive at one and the same time, enabling them to recognize their prey and seize it, to feel a danger and make the effort to avoid it. The various prolongations of the pro tozoa, the ambulacra of the echinodermata, are organs of movement as well as of tactile percep tion; the stinging apparatus of the coelenterata is an instrument of perception as well as a means of defence. In a word, the more immediate the reaction is compelled to be, the more must percep tion resemble a mere contact; and the complete process of perception and of reaction can then hardly be distinguished from a mechanical impul sion followed by a necessary movement. But in the measure that the reaction becomes more un certain, and allows more room for suspense, does the distance increase at which the animal is sensible of the action of that which interests it. By sight, by hearing, it enters into relation with an ever greater number of things, and is subject to more and more distant influences; and, whether these objects promise an advantage or threaten a danger, both promises and threats defer the date of their fulfilment. The degree of independence of which a living being is master, or, as we shall say, the zone of indetermination which surrounds its activity, allows, then, of an a 'priori estimate of the number and the distance of the things with which it is in relation. Whatever this relation may be, whatever be the inner nature of percep tion, we can affirm that its amplitude gives the exact measure of the indetermination of the act which is to follow. So that we can formulate this law: perception is master of space in the exact measure in which action is master of time.
But why does this relation of the organism to more or less distant objects take the particular form what then °f conscious perception? We have Sonsdous-* examined what takes place in the orp?eiiLinary ganized body, we have seen movements hmts- transmitted or inhibited, metamor phosed into accomplished actions or broken up into nascent actions. These movements appear to us to concern action, and action alone; they remain absolutely foreign to the process of repre sentation. We then considered action itself, and the indetermination which surrounds it and is implied in the structure of the nervous system, — an indetermination to which this system seems to point much more than to representation.
From this indetermination, accepted as a fact, we have been able to infer the necessity of a perception, that is to say, of a variable relation between the living being and the more or less distant influence of the objects which interest it. How is it that this perception is consciousness, and why does everything happen as if this con sciousness were born of the internal movements of the cerebral substance?
To answer this question, we will first simplify considerably the conditions under which conscious perception takes place. In fact, there is no perception which is not full of memories. With the immediate and present data of our senses we mingle a thousand details out of our past experience. In most cases these memories supplant our actual perceptions, of which we then retain only a few hints, thus using them merely as ' signs ' that recall to us former images. The convenience and the rapidity of perception are bought at this price; but hence also springs every kind of illusion. Let us, for the purposes of study, substitute for this perception, impregnated with our past, a per ception that a consciousness would have if it were supposed to be ripe and full-grown, yet confined to the present and absorbed, to the exclusion of all else, in the task of moulding itself upon the external object. — It may be urged that this is an arbitrary hypothesis, and that such an ideal perception, obtained by the CHA*. I THE CHOICE OF IMAGES 25 elimination of individual accidents, has no corre spondence with reality. — But we hope to show that the individual accidents are merely grafted on to this impersonal perception, which is at the very root of our knowledge of things; and that just because philosophers have overlooked it, because they have not distinguished it from that which memory adds to or subtracts from it, they have taken perception as a whole for a kind of interior and subjective vision, which would then differ from memory only by its greater intensity. This will be our first hypothesis. But it leads naturally to another. However brief we suppose any perception to be, it always occupies a certain duration, and involves consequently an effort of memory which prolongs one into another a plurality of moments. As we shall endeavour to show, even the 'subjectivity' of sensible quali ties consists above all else in a kind of contraction of the real, effected by our memory. In short, memory in these two forms, covering as it does with a cloak of recollections a core of immediate percep tion, and also contracting a number of external moments into a single internal moment, con stitutes the principal share of individual con sciousness in perception, the subjective side of the knowledge of things; and, since we must neglect this share in order to make our idea clearer, we shall go too far along the path we have chosen. But we shall only have to retrace our steps and to correct, especially by bringing memory back again, whatever may be excessive in our conclusions. What follows, therefore, must be regarded as only a schematic rendering, and we ask that perception should be provisionally understood to mean not my concrete and com plex perception — that which is enlarged by memories and offers always a certain breadth of duration — but a pure perception, I mean a percep tion which exists in theory rather than in fact and would be possessed by a being placed where I am, living as I live, but absorbed in the present and capable, by giving up every form of memory, of obtaining a vision of matter both immediate and instantaneous. Adopting this hypothesis, let us consider how conscious per ception may be explained.
To deduce consciousness would be, indeed, a bold undertaking; but it is really not necessary here, because by positing the material world we assume an aggregate of images, and morereflectedfrom over because it is impossible to assume thoiuh by a anything else. No theory of matter escapes mirror. ^his necessity. Reduce matter to atoms in motion: these atoms, though denuded of physical qualities, are determined only in relation to an eventual vision and an eventual contact, the one without light and the other without materiality. Condense atoms into centres of force, dissolve them into vortices revolving in a continuous fluid: this fluid, these movements, these centres, can themselves be determined only in relation to an impotent touch, an ineffectual impulsion, a colour less light; they are still images. It is true that an image may be without being perceived; it may be present without being represented; and the distance between these two terms, presence and representation, seems just to measure the interval between matter itself and our con scious perception of matter. But let us examine the point more closely, and see in what this difference consists. If there were more in the second term than in the first, if, in order to pass from presence to representation, it were necessary to add something, the barrier would indeed be insuperable, and the passage from matter to perception would remain wrapt in impenetrable mystery. It would not be the same if it were possible to pass from the first term to the second by way of diminution, and if the representation of an image were less than its presence; for it would then suffice that the images present should be compelled to abandon some thing of themselves in order that their mere pre sence should convert them into representations.