# Matter and Memory/Summary and Conclusion

I. The idea that we have disengaged from the facts and confirmed by reasoning is that our bodyThe body an instrument of action only. is an instrument of action, and of action only. In no degree, in no sense, under no aspect, does it serve to prepare, far less to explain, a representation. Consider external perception: there is only a difference of degree, not of kind, between the so-called perceptive faculties of the brain and the reflex functions of the spinal cord. While the spinal cord transforms the excitations received into movements which are more or less necessarily executed, the brain puts them into relation with motor mechanisms 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 repetition 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 ​store up recollections or images. Thus, neither in perception, nor in memory, nor a fortiori in the higher attainments of mind, does the body contribute directly to representation. By developing 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.
II. All the difficulties raised by this problem, either in ordinary dualism, or in materialism andPerception and memory, the physical and the mental, are not mere duplicates of each other. idealism, come from considering, in the phenomena of perception and memory, the physical and the mental as duplicates the one of the other. Suppose I place myself at the materialist point of view of the epiphenomenal consciousness: I am quite unable to understand why certain cerebral phenomena are accompanied by consciousness, that is to say, of what use could be, or how could ever arise, the conscious repetition of the material universe I have begun by positing. Suppose I prefer idealism: I then allow myself only perceptions, and my body is one of them. But whereas observation shows me that the images I perceive are entirely changed by very slight alterations of the image I call my body (since I have only to shut my eyes and my visual universe disappears), science assures me that all phenomena must succeed and condition one another according to a determined order, in which ​effects are strictly proportioned to causes. I am obliged, therefore, to seek, in the image which I call my body, and which follows me everywhere, for changes which shall be the equivalents—but the well-regulated equivalents, now deducible from each other—of the images which succeed one another around my body: the cerebral movements, to which I am led back in this way, again are the duplicates of my perceptions. It is true that these movements are still perceptions, 'possible' perceptions,—so that this second hypothesis is more intelligible than the first; but, on the other hand, it must suppose, in its turn, an inexplicable correspondence between my real perception of things and my possible perception of certain cerebral movements which do not in any way resemble these things. When we look at it closely, we shall see that this is the reef upon which all idealism is wrecked: there is no possible transition from the order which is perceived by our senses to the order which we are to conceive for the sake of our science,—or, if we are dealing more particularly with the Kantian idealism, no possible transition from sense to understanding.—So my only refuge seems to be ordinary dualism. I place matter on this side, mind on that, and I suppose that cerebral movements are the cause or the occasion of my representation of objects. But if they are its cause, if they are enough to produce it, I must fall back, step by step, upon the material​istic hypothesis of an epiphenomenal consciousness. If they are only its occasion, I thereby suppose that they do not resemble it in any way, and so, depriving matter of all the qualities which I conferred upon it in my representation, I come back to idealism. Idealism and materialism are then the two poles between which this kind of dualism will always oscillate; and when, in order to maintain the duality of substances, it decides to make them both of equal rank, it will be led to regard them as two translations of one and the same original, two parallel and predetermined developments of a single principle, and thus to deny their reciprocal influence, and, by an inevitable consequence, to sacrifice freedom.
Now, if we look beneath these three hypotheses, we find that they have a common basis:The mistake is due to our believing that perception and memory are pure knowledge, whereas they point to action. all three regard the elementary operations of the mind, perception and memory, as operations of pure knowledge. What they place at the origin of consciousness is either the useless duplicate of an external reality or the inert material of an intellectual construction entirely disinterested: but they always neglect the relation of perception with action and of memory with conduct. Now, it is no doubt possible to conceive, as an ideal limit, a memory and a perception that are disinterested; but, in fact, it is towards action that memory and perception are turned; it is action that the body pre​pares. Do we consider perception? The growing complexity of the nervous system shunts the excitation received on to an ever larger variety of motor mechanisms, and so sketches out simultaneously an ever larger number of possible actions. Do we turn to memory? We note that its primary function is to evoke all those past perceptions which are analogous to the present perception, to recall to us what preceded and followed them, and so to suggest to us that decision which is the most useful. But this is not all. By allowing us to grasp in a single intuition multiple moments of duration, it frees us from the movement of the flow of things, that is to say, from the rhythm of necessity. The more of these moments memory can contract into one, the firmer is the hold which it gives to us on matter: so that the memory of a living being appears indeed to measure, above all, its powers of action upon things, and to be only the intellectual reverberation of this power. Let us start, then, from this energy, as from the true principle: let us suppose that the body is a centre of action, and only a centre of action. We must see what consequences thence result for perception, for memory, and for the relations between body and mind.
III. To take perception first. Here is my body with its 'perceptive centres.' These centresPerception gives us 'things-in-themselves.' vibrate, and I have the representation of things. On the other hand I have supposed that these vibrations can ​neither produce nor translate my perception. It is, then, outside them. Where is it? I cannot hesitate as to the answer: positing my body, I posit a certain image, but with it also the aggregate of the other images, since there is no material image which does not owe its qualities, its determinations, in short its existence, to the place which it occupies in the totality of the universe. My perception can, then, only be some part of these objects themselves; it is in them rather than they in it. But what is it exactly within them? I see that my perception appears to follow all the vibratory detail of the so-called sensitive nerves; and on the other hand I know that the rôle of their vibrations is solely to prepare the reaction of my body on neighbouring bodies, to sketch out my virtual actions. Perception, therefore, consists in detaching, from the totality of objects, the possible action of my body upon them. Perception appears, then, as only a choice. It creates nothing; its office, on the contrary, is to eliminate from the totality of images all those on which I can have no hold, and then, from each of those which I retain, all that does not concern the needs of the image which I call my body. Such is, at least, much simplified, the way we explain or describe schematically what we have called pure perception. Let us mark out at once the intermediate place which we thus take up between realism and idealism.
That every reality has a kinship, an analogy, ​in short a relation with consciousness—this isThough it gives us only a part of these things. what we concede to idealism by the very fact that we term things 'images.' No philosophical doctrine, moreover, provided that it is consistent with itself, can escape from this conclusion. But if we could assemble all the states of consciousness, past, present, and possible, of all conscious beings, we should still only have gathered a very small part of material reality, because images outrun perception on every side. It is just these images that science and metaphysic seek to reconstitute, thus restoring the whole of a chain of which our perception grasps only a few links. But in order thus to discover between perception and reality the relation of the part to the whole, it is necessary to leave to perception its true office, which is to prepare actions. This is what idealism fails to do. Why is it unable, as we said just now, to pass from the order manifested in perception to the order which is successful in science, that is to say, from the contingency with which our sensations appear to follow each other to the determinism which binds together the phenomena of nature? Precisely because it attributes to consciousness, in perception, a speculative rôle, so that it is impossible to see what interest this consciousness has in allowing to escape, between two sensations for instance, the intermediate links through which the second might be deduced from the first. These intermediaries and their strict order thus ​remain obscure, whether, with Mill, we make the intermediaries into 'possible sensations,' or, with Kant, hold the substructure of the order to be the work of an impersonal understanding. But suppose that my conscious perception has an entirely practical destination, that it simply indicates, in the aggregate of things, that which interests my possible action upon them: I can then understand that all the rest escapes me, and that, nevertheless, all the rest is of the same nature as what I perceive. My consciousness of matter is then no longer either subjective, as it is for English idealism, or relative, as it is for the Kantian idealism. It is not subjective, for it is in things rather than in me. It is not relative, because the relation between the 'phenomenon' and the 'thing' is not that of appearance to reality, but merely that of the part to the whole.
Here we seem to return to realism. But realism, unless corrected on an essential point, is asThe mistake is to set up homogeneous space as a real or even ideal medium prior to extension. inacceptable as idealism, and for the same reason. Idealism, we said, cannot pass from the order manifested in perception to the order which is successful in science, that is to say to reality. Inversely, realism fails to draw from reality the immediate consciousness which we have of it. Taking the point of view of ordinary realism, we have, on the one hand, a composite matter made up of more or less independent parts, diffused through​out space, and, on the other, a mind which can have no point of contact with matter, unless it be, as materialists maintain, the unintelligible epiphenomenon. If we prefer the standpoint of the Kantian realism, we find between the 'thing-in-itself,' that is to say the real, and the 'sensuous manifold' from which we construct our knowledge, no conceivable relation, no common measure. Now, if we get to the bottom of these two extreme forms of realism, we see that they converge towards the same point: both raise homogeneous space as a barrier between the intellect and things. The simpler realism makes of this space a real medium, in which things are in suspension; Kantian realism regards it as an ideal medium, in which the multiplicity of sensations is coördinated; but for both of them this medium is given to begin with, as the necessary condition of what comes to abide in it. And if we try to get to the bottom of this common hypothesis, in its turn, we find that it consists in attributing to homogeneous space a disinterested office: space is supposed either merely to uphold material reality, or to have the function, still purely speculative, of furnishing sensations with means of coördinating themselves. So that the obscurity of realism, like that of idealism, comes from the fact that, in both of them, our conscious perception and the conditions of our conscious perception are assumed to point to pure knowledge, not to action.—But suppose now ​that this homogeneous space is not logically anterior, but posterior to material things and to the pure knowledge which we can have of them; suppose that extensity is prior to space; suppose that homogeneous space concerns our action and only our action, being like an infinitely fine network which we stretch beneath material continuity in order to render ourselves masters of it, to decompose it according to the plan of our activities and our needs. Then, not only has our hypothesis the advantage of bringing us into harmony with science, which shows us each thing exercising an influence on all the others and consequently occupying, in a certain sense, the whole of the extended (although we perceive of this thing only its centre and mark its limits at the point where our body ceases to have any hold upon it). Not only has it the advantage, in metaphysic, of suppressing or lessening the contradictions raised by divisibility in space,—contradictions which always arise, as we have shown, from our failure to dissociate the two points of view, that of action from that of knowledge. It has, above all, the advantage of overthrowing the insurmountable barriers raised by realism between the extended world and our perception of it. For whereas this doctrine assumes on the one hand an external reality which is multiple and divided, and on the other sensations alien from extensity and without possible contact with it, we find that concrete extensity is not really ​divided, any more than immediate perception is in truth unextended. Starting from realism, we come back to the point to which idealism had led us; we replace perception in things. And we see realism and idealism ready to come to an understanding when we set aside the postulate, uncritically accepted by both, which served them as a common frontier.
To sum up: if we suppose an extended continuum, and, in this continuum, the centre of real action which is represented by our body, its activity will appear to illumine all those parts of matter with which at each successive moment it can deal. The same needs, the same power of action, which have delimited our body in matter, will also carve out distinct bodies in the surrounding medium. Everything will happen as if we allowed to filter through us that action of external things which is real, in order to arrest and retain that which is virtual: this virtual action of things upon our body and of our body upon things is our perception itself. But since the excitations which our body receives from surrounding bodies determine unceasingly, within its substance, nascent reactions,—since these internal movements of the cerebral substance thus sketch out at every moment our possible action on things, the state of the brain exactly corresponds to the perception. It is neither its cause, nor its effect, nor in any sense its duplicate: it merely continues it, the perception being our virtual action and the cerebral state our action already begun.
​IV. But this theory of 'pure perception' had to be both qualified and completed in regard to twoReal action and virtual action. Transition to affection and memory. points. For the so-called 'pure' perception, which is like a fragment of reality, detached just as it is, would belong to a being unable to mingle with the perception of other bodies that of its own body, that is to say, its affections; nor with its intuition of the actual moment that of other moments, that is to say, its memory. In other words, we have, to begin with, and for the convenience of study, treated the living body as a mathematical point in space and conscious perception as a mathematical instant in time. We then had to restore to the body its extensity and to perception its duration. By this we restored to consciousness its two subjective elements, affectivity and memory.
What is an affection? Our perception, we said, indicates the possible action of our body on others. But our body, being extended, is capable of acting upon itself as well as upon other bodies. Into our perception, then, something of our body must enter. When we are dealing with external bodies, these are, by hypothesis, separated from ours by a space, greater or less, which measures the remoteness in time of their promise or of their menace: this is why our perception of these bodies indicates only possible actions. But the more the distance diminishes between these bodies and our own, the more the possible action ​tends to transform itself into a real action, the call for action becoming more urgent in the measure and proportion that the distance diminishes. And when this distance is nil, that is to say when the body to be perceived is our own body, it is a real and no longer a virtual action that our perception sketches out. Such is, precisely, the nature of pain, an actual effort of the damaged part to set things to rights, an effort that is local, isolated, and thereby condemned to failure, in an organism which can no longer act except as a whole. Pain is therefore in the place where it is felt, as the object is at the place where it is perceived. Between the affection felt and the image perceived there is this difference, that the affection is within our body, the image outside our body. And that is why the surface of our body, the common limit of this and of other bodies, is given to us in the form both of sensations and of an image.
In this inferiority of affective sensation consists its subjectivity; in that exteriority of images in general their objectivity. But here again we encounter the ever-recurring mistake with which we have been confronted throughout this work. It is supposed that perception and sensation exist for their own sake; the philosopher ascribes to them an entirely speculative function; and, as he has overlooked those real and virtual actions with which sensation and perception are bound up and by which, according as the action ​is virtual or real, perception and sensation are characterized and distinguished, he becomes unable to find any other difference between them than a difference of degree. Then, profiting by the fact that affective sensation is but vaguely localized (because the effort it involves is an indistinct effort) at once he declares it to be unextended; and these attenuated affections or unextended sensations he sets up as the material with which we are supposed to build up images in space. Thereby he condemns himself to an impossibility of explaining either whence arise the elements of consciousness, or sensations, which he sets up as so many absolutes, or how, unextended, they find their way to space and are coordinated there, or why, in it, they adopt a particular order rather than any other, or, finally, how they manage to make up an experience which is regular and common to all men. This experience, the necessary field of our activity, is, on the contrary, what we should start from. Pure perceptions, therefore, or images, are what we should posit at the outset. And sensations, far from being the materials from which the image is wrought, will then appear as the impurity which is introduced into it, being that part of our own body which we project into all others.
V. But, as long as we confine ourselves to sensation and to pure perception, we can hardly be said to be dealing with the spirit. No doubt we demonstrate, as against the theory of an ​epiphenomenal consciousness, that no cerebralMemory is spirit, not a manifestation of matter. state is the equivalent of a perception. No doubt the choice of perceptions from among images in general is the effect of a discernment which foreshadows spirit. No doubt also the material universe itself, defined as the totality of images, is a kind of consciousness, a consciousness in which everything compensates and neutralizes everything else, a consciousness of which all the potential parts, balancing each other by a reaction which is always equal to the action, reciprocally hinder each other from standing out. But to touch the reality of spirit we must place ourselves at the point where an individual consciousness, continuing and retaining the past in a present enriched by it, thus escapes the law of necessity, the law which ordains that the past shall ever follow itself in a present which merely repeats it in another form, and that all things shall ever be flowing away. When we pass from pure perception to memory, we definitely abandon matter for spirit.
VI. The theory of memory, around which the whole of our work centres, must be both the theoretic consequence and the experimental verification of our theory of pure perception. That the cerebral states which accompany perception are neither its cause nor its duplicate, and that perception bears to its physiological counterpart the relation of a virtual action to an action begun—this we cannot substantiate by ​facts, since on our hypothesis everything is bound to happen as if perception were a consequence of the state of the brain. For, in pure perception, the perceived object is a present object, a body which modifies our own. Its image is then actually given, and therefore the facts permit us to say indifferently (though we are far from knowing our own meaning equally well in the two cases) that the cerebral modifications sketch the nascent reactions of our body or that they create in consciousness the duplicate of the present image. But with memory it is otherwise, for a remembrance is the representation of an absent object. Here the two hypotheses must have opposite consequences. If, in the case of a present object, a state of our body is thought sufficient to create the representation of the object, still more must it be thought so in the case of an object that is represented though absent. It is necessary therefore, on this theory, that the remembrance should arise from the attenuated repetition of the cerebral phenomenon which occasioned the primary perception, and should consist simply in a perception weakened. Whence this double thesis: Memory is only a function of the brain, and there is only a difference of intensity between perception and recollection.—If, on the contrary, the cerebral state in no way begets our perception of the present object but merely continues it, it may also prolong and convert into action the recollection of it which we summon up, but it cannot ​give birth to that recollection. And as, on the other hand, our perception of the present object is something of that object itself, our representation of the absent object must be a phenomenon of quite another order than perception, since between presence and absence there are no degrees, no intermediate stages. Whence this double thesis, which is the opposite of the former: Memory is something other than a function of the brain, and there is not merely a difference of degree, but of kind, between perception and recollection.—The conflict between the two theories now takes an acute form; and this time experience can judge between them.
We will not here recapitulate in detail the proof we have tried to elaborate, but merely recall its essential points. All the arguments from fact, which may be invoked in favour of a probable accumulation of memories in the cortical substance, are drawn from localized disorders of memory. But, if recollections were really deposited in the brain, to definite gaps in memory characteristic lesions of the brain would correspond. Now, in those forms of amnesia in which a whole period of our past existence, for example, is abruptly and entirely obliterated from memory, we do not observe any precise cerebral lesion; and, on the contrary, in those disorders of memory where cerebral localization is distinct and certain, that is to say, in the different types of aphasia and in the diseases of visual or auditory recognition, we do not find that certain ​definite recollections are as it were torn from their seat, but that it is the whole faculty of remembering that is more or less diminished in vitality, as if the subject had more or less difficulty in bringing his recollections into contact with the present situation. The mechanism of this contact was, therefore, what we had to study in order to ascertain whether the office of the brain is not rather to ensure its working than to imprison the recollections in cells.
We were thus led to follow through its windings the progressive movement by whichRecognition. past and present come into contact with each other, that is to say, the process of recognition. And we found, in fact, that the recognition of a present object might be effected in two absolutely different ways, but that in neither case did the brain act as a reservoir of images. Sometimes, by an entirely passive recognition, rather acted than thought, the body responds to a perception that recurs by a movement or attitude that has become automatic: in this case everything is explained by the motor apparatus which habit has set up in the body, and lesions of the memory may result from the destruction of these mechanisms. Sometimes, on the other hand, recognition is actively produced by memory-images which go out to meet the present perception; but then it is necessary that these recollections, at the moment that they overlie the perception, should be able to set going ​in the brain the same machinery that perception ordinarily sets to work in order to produce actions; if not foredoomed to impotence, they will have no tendency to become actual. And this is why, in all cases where a lesion of the brain attacks a certain category of recollections, the affected recollections do not resemble each other by all belonging to the same period, for instance, or by any logical relationship to each other, but simply in that they are all auditive, or all visual, or all motor. That which is damaged appears to be the various sensorial or motor areas, or, more often still, those appendages which permit of their being set going from within the cortex, rather than the recollections themselves. We even went further, and by an attentive study of the recognition of words, as also of the phenomena of sensory aphasia, we endeavoured to prove that recognition is in no way effected by a mechanical awakening of memories that are asleep in the brain. It implies, on the contrary, a more or less high degree of tension in consciousness, which goes to fetch pure recollections in pure memory in order to materialize them progressively by contact with the present perception.
But what is this pure memory, what are pure recollections? By the answer to this enquiry we completed the demonstration of our thesis. We had just established its first point, that is to say, that memory is something other than a function of the brain. We had still to show, by the analysis ​of 'pure recollection,' that there is not between recollection and perception a mere difference of degree but a radical difference of kind.
VII. Let us point out to begin with the metaphysical, and no longer merely psychological,The different planes of consciousness. bearing of this last problem. No doubt we have a thesis of pure psychology in a proposition such as this: recollection is a weakened perception. But let there be no mistake: if recollection is only a weakened perception, inversely perception must be something like an intenser memory. Now the germ of English idealism is to be found here. This idealism consists in finding only a difference of degree, and not of kind, between the reality of the object perceived and the ideality of the object conceived. And the belief that we construct matter from our interior states and that perception is only a true hallucination, also arises from this thesis. It is this belief that we have always combated whenever we have treated of matter. Either, then, our conception of matter is false, or memory is radically distinct from perception.
We have thus transposed a metaphysical problem so as to make it coincide with a psychological problem which direct observation is able to solve. How does psychology solve it? If the memory of a perception were but this perception weakened, it might happen to us, for instance, to take the perception of a slight sound for the recol​lection of a loud noise. Now such a confusion never occurs. But we may go further, and say that the consciousness of a recollection never occurs as an actual weak state which we try to relegate to the past so soon as we become aware of its weakness. How, indeed, unless we already possessed the representation of a past previously lived, could we relegate to it the less intense psychical states, when it would be so simple to set them alongside of strong states as a present experience more confused beside a present experience more distinct? The truth is that memory does not consist in a regression from the present to the past, but, on the contrary, in a progress from the past to the present. It is in the past that we place ourselves at a stroke. We start from a 'virtual state' which we lead onwards, step by step, through a series of different planes of consciousness, up to the goal where it is materialized in an actual perception; that is to say, up to the point where it becomes a present, active state; in fine, up to that extreme plane of our consciousness against which our body stands out. In this virtual state pure memory consists.
How is it that the testimony of consciousness on this point is misunderstood? How is it that we make of recollection a weakened perception, of which it is impossible to say either why we relegate it to the past, how we rediscover its date, or by what right it reappears at one moment rather than at another? Simply because we forget the ​practical end of all our actual psychical states. Perception is made into a disinterested work of the mind, a pure contemplation. Then, as pure recollection can evidently be only something of this kind (since it does not correspond to a present and urgent reality), memory and perception become states of the same nature, and between them no other difference than a difference of intensity can be found. But the truth is that our present should not be defined as that which is more intense: it is that which acts on us and which makes us act, it is sensory and it is motor;—our present is, above all, the state of our body. Our past, on the contrary, is that which acts no longer but which might act, and will act by inserting itself into a present sensation of which it borrows the vitality. It is true that, from the moment when the recollection actualizes itself in this manner, it ceases to be a recollection and becomes once more a perception.
We understand then why a remembrance cannot be the result of a state of the brain. The state of the brain continues the remembrance; it gives it a hold on the present by the materiality which it confers upon it: but pure memory is a spiritual manifestation. With memory we are in very truth in the domain of spirit.
VIII. It was not our task to explore this domain. Placed at the confluenceAssociationism and general ideas. of mind and matter, desirous ​chiefly of seeing the one flow into the other, we had only to retain, of the spontaneity of intellect, its place of conjunction with bodily mechanism. In this way we were led to consider the phenomena of association and the birth of the simplest general ideas.
What is the cardinal error of associationism? It is to have set all recollections on the same plane, to have misunderstood the greater or less distance which separates them from the present bodily state, that is from action. Thus associationism is unable to explain either how the recollection clings to the perception which evokes it, or why association is effected by similarity or contiguity rather than in any other way, or, finally, by what caprice a particular recollection is chosen among the thousand others which similarity or contiguity might equally well attach to the present perception. This means that associationism has mixed and confounded all the different planes of consciousness, and that it persists in regarding a less complete as a less complex recollection, whereas it is in reality a recollection less dreamed, more impersonal, nearer to action and therefore more capable of moulding itself—like a ready-made garment—upon the new character of the present situation. The opponents of associationism have, moreover, followed it on to this ground. They combat the theory because it explains the higher operations of the mind by association, but not because it misunderstands the true nature of ​association itself. Yet this is the original vice of associationism.
Between the plane of action—the plane in which our body has condensed its past into motor habits,—and the plane of pure memory, where our mind retains in all its details the picture of our past life, we believe that we can discover thousands of different planes of consciousness, a thousand integral and yet diverse repetitions of the whole of the experience through which we have lived. To complete a recollection by more personal details does not at all consist in mechanically juxtaposing other recollections to this, but in transporting ourselves to a wider plane of consciousness, in going away from action in the direction of dream. Neither does the localizing of a recollection consist in inserting it mechanically among other memories, but in describing, by an increasing expansion of the memory as a whole, a circle large enough to include this detail from the past. These planes, moreover, are not given as ready-made things superposed the one on the other. Rather they exist virtually, with that existence which is proper to things of the spirit. The intellect, for ever moving in the interval which separates them, unceasingly finds them again, or creates them anew: the life of intellect consists in this very movement. Then we understand why the laws of association are similarity and contiguity rather than any other laws, and why memory chooses among recollections which are similar or contiguous certain ​images rather than other images, and, finally, how by the combined work of body and mind the earliest general ideas are formed. The interest of a living being lies in discovering in the present situation that which resembles a former situation, and then in placing alongside of that present situation what preceded and followed the previous one, in order to profit by past experience. Of all the associations which can be imagined, those of resemblance and contiguity are therefore at first the only associations that have a vital utility. But, in order to understand the mechanism of these associations and above all the apparently capricious selection which they make of memories, we must place ourselves alternately on the two extreme planes of consciousness which we have called the plane of action and the plane of dream. In the first are displayed only motor habits; these may be called associations which are acted or lived, rather than represented: here resemblance and contiguity are fused together, for analogous external situations, as they recur, have ended by connecting together certain bodily movements, and thenceforward the same automatic reaction, in which we unfold these contiguous movements, will also draw from the situation which occasions them its resemblance with former situations. But, as we pass from movements to images and from poorer to richer images, resemblance and contiguity part company: they end by contrasting sharply with each other on that ​other extreme plane where no action is any longer affixed to the images. The choice of one resemblance among many, of one contiguity among others, is, therefore, not made at random: it depends on the ever varying degree of the tension of memory, which, according to its tendency to insert itself in the present act or to withdraw from it, transposes itself as a whole from one key into another. And this double movement of memory between its two extreme limits also sketches out, as we have shown, the first general ideas,—motor habits ascending to seek similar images in order to extract resemblances from them, and similar images coming down towards motor habits, to fuse themselves, for instance, in the automatic utterance of the word which makes them one. The nascent generality of the idea consists, then, in a certain activity of the mind, in a movement between action and representation. And this is why, as we have said, it will always be easy for a certain philosophy to localize the general idea at one of the two extremities, to make it crystallize into words or evaporate into memories, whereas it really consists in the transit of the mind as it passes from one term to the other.
IX. By representing elementary mental activity in this manner to ourselves, and by thusThe union of body and mind. making of our body and all that surrounds it the pointed end ever moving, ever driven into the future by the ​weight of our past, we were able to confirm and illustrate what we had said of the function of the body, and at the same time to prepare the way for an approximation of body and mind.
For after having successively studied pure perception and pure memory, we still had to bring them together. If pure recollection is already spirit, and if pure perception is still in a sense matter, we ought to be able, by placing ourselves at their meeting place, to throw some light on the reciprocal action of spirit and matter. 'Pure,' that is to say instantaneous, perception is, in fact, only an ideal, an extreme. Every perception fills a certain depth of duration, prolongs the past into the present, and thereby partakes of memory. So that if we take perception in its concrete form, as a synthesis of pure memory and pure perception, that is to say of mind and matter, we compress within its narrowest limits the problem of the union of soul and body. This is the attempt we have made especially in the latter part of this essay.
The opposition of the two principles, in dualism in general, resolves itself into the threefold opposition of the inextended and the extended, quality and quantity, freedom and necessity. If our conception of the function of the body, if our analyses of pure perception and pure memory, are destined to throw light on any aspect of the correlation of body and mind, it can only be on condition of suppressing or toning down these ​three oppositions. We will, then, examine them in turn, presenting here in a more metaphysical form the conclusions which we have made a point of drawing from psychology alone.
1st. If we imagine on the one hand the extended really divided into corpuscles, for example, andExtension. on the other a consciousness with sensations, in themselves inextensive, which come to project themselves into space, we shall evidently find nothing common to such matter and such a consciousness, to body and mind. But this opposition between perception and matter is the artificial work of an understanding which decomposes and recomposes according to its habits or its laws: it is not given in immediate intuition. What is given are not inextensive sensations: how should they find their way back to space, choose a locality within it, and coördinate themselves there so as to build up an experience that is common to all men? And what is real is not extension, divided into independent parts: how, being deprived of all possible relationship to our consciousness, could it unfold a series of changes of which the relations and the order exactly correspond to the relations and the order of our representations? That which is given, that which is real, is something intermediate between divided extension and pure inextension. It is what we have termed the extensive. Extensity is the most salient quality of perception. It is in consolidating and in subdividing ​it by means of an abstract space, stretched by us beneath it for the needs of action, that we constitute the composite and infinitely divisible extension. It is, on the other hand, in subtilizing it, in making it, in turn, dissolve into affective sensations and evaporate into a counterfeit of pure ideas, that we obtain those inextensive sensations with which we afterwards vainly endeavour to reconstitute images. And the two opposite directions in which we pursue this double labour open quite naturally before us, because it is a result of the very necessities of action that extension should divide itself up for us into absolutely independent objects (whence an encouragement to go on subdividing extension); and that we should pass by insensible degrees from affection to perception (whence a tendency to suppose perception more and more inextensive). But our understanding, of which the function is to set up logical distinctions, and consequently clean-cut oppositions, throws itself into each of these ways in turn, and follows each to the end. It thus sets up, at one extremity, an infinitely divisible extension, at the other sensations which are absolutely inextensive. And it creates thereby the opposition which it afterwards contemplates amazed.
2nd. Far less artificial is the opposition between quality and quantity, that is to say betweenTension. consciousness and movement: but this opposition is radical only if we have ​already accepted the other. For if you suppose that the qualities of things are nothing but inextensive sensations affecting a consciousness, so that these qualities represent merely, as so many symbols, homogeneous and calculable changes going on in space, you must imagine between these sensations and these changes an incomprehensible correspondence. On the contrary, as soon as you give up establishing between them a priori this factitious contrariety, you see the barriers which seemed to separate them fall one after another. First, it is not true that consciousness, turned round on itself, is confronted with a merely internal procession of inextensive perceptions. It is inside the very things perceived that you put back pure perception, and the first obstacle is thus removed. You are confronted with a second, it is true: the homogeneous and calculable changes on which science works seem to belong to multiple and independent elements, such as atoms, of which these changes appear as mere accidents, and this multiplicity comes in between the perception and its object. But if the division of the extended is purely relative to our possible action upon it, the idea of independent corpuscles is a fortiori schematic and provisional. Science itself, moreover, allows us to discard it; and so the second barrier falls. A last interval remains to be over-leapt: that which separates the heterogeneity of qualities from the apparent homogeneity of movements that ​are extended. But, just because we have set aside the elements, atoms or what not, to which these movements had been affixed, we are no longer dealing with that movement which is the accident of a moving body, with that abstract motion which the mechanician studies and which is nothing, at bottom, but the common measure of concrete movements. How could this abstract motion, which becomes immobility when we alter our point of reference, be the basis of real changes, that is, of changes that are felt? How, composed as it is of a series of instantaneous positions, could it fill a duration of which the parts go over and merge each into the others? Only one hypothesis, then, remains possible; namely, that concrete movement, capable, like consciousness, of prolonging its past into its present, capable, by repeating itself, of engendering sensible qualities, already possesses something akin to conciousness, something akin to sensation. On this theory, it might be this same sensation diluted, spread out over an infinitely larger number of moments, this same sensation quivering, as we have said, like a chrysalis within its envelope. Then a last point would remain to be cleared up: how is the contraction effected,—the contraction no longer of homogeneous movements into distinct qualities, but of changes that are less heterogeneous into changes that are more heterogeneous? But this question is answered by our analysis of concrete perception: this ​perception, the living synthesis of pure perception and pure memory, necessarily sums up in its apparent simplicity an enormous multiplicity of moments. Between sensible qualities, as regarded in our representation of them, and these same qualities treated as calculable changes, there is therefore only a difference in rhythm of duration, a difference of internal tension. Thus, by the idea of tension we have striven to overcome the opposition between quality and quantity, as by the idea of extension that between the inextended and the extended. Extension and tension admit of degrees, multiple but always determined. The function of the understanding is to detach from these two genera, extension and tension, their empty container, that is to say, homogeneous space and pure quantity, and thereby to substitute, for supple realities which permit of degrees, rigid abstractions born of the needs of action, which can only be taken or left; and to create thus, for reflective thought, dilemmas of which neither alternative is accepted by reality.
3rd. But if we regard in this way the relations of the extended to the inextended, of qualityFreedom and necessity. to quantity, we shall have less difficulty in comprehending the third and last opposition, that of freedom and necessity. Absolute necessity would be represented by a perfect equivalence of the successive moments of duration, each to each. Is it so with the duration ​of the material universe? Can each moment be mathematically deduced from the preceding moment? We have throughout this work, and for the convenience of study, supposed that it was really so; and such is, in fact, the distance between the rhythm of our duration and that of the flow of things, that the contingency of the course of nature, so profoundly studied in recent philosophy, must, for us, be practically equivalent to necessity. So let us keep to our hypothesis, though it might have to be attenuated. Even so, freedom is not in nature an imperium in imperio. We have said that this nature might be regarded as a neutralized and consequently a latent consciousness, a consciousness of which the eventual manifestations hold each other reciprocally in check, and annul each other precisely at the moment when they might appear. The first gleams which are thrown upon it by an individual consciousness do not therefore shine on it with an unheralded light: this consciousness does but remove an obstacle; it extracts from the whole that is real a part that is virtual, chooses and finally disengages that which interests it; and although, by that intelligent choice, it indeed manifests that it owes to spirit its form, it assuredly takes from nature its matter. Moreover, while we watch the birth of that consciousness we are confronted, at the same time, by the apparition of living bodies, capable, even in their simplest forms, of movements spontaneous and unforeseen. ​The progress of living matter consists in a differentiation of function which leads first to the production and then to the increasing complication of a nervous system capable of canalizing excitations and of organizing actions: the more the higher centres develop, the more numerous become the motor paths among which the same excitation allows the living being to choose, in order that it may act. An ever greater latitude left to movement in space—this indeed is what is seen. What is not seen is the growing and accompanying tension of consciousness in time. Not only, by its memory of former experience, does this consciousness retain the past better and better, so as to organize it with the present in a newer and richer decision; but, living with an intenser life, contracting, by its memory of the immediate experience, a growing number of external moments in its present duration, it becomes more capable of creating acts of which the inner indetermination, spread over as large a multiplicity of the moments of matter as you please, will pass the more easily through the meshes of necessity. Thus, whether we consider it in time or in space, freedom always seems to have its roots deep in necessity and to be intimately organized with it. Spirit borrows from matter the perceptions on which it feeds, and restores them to matter in the form of movements which it has stamped with its own freedom.