Images as data—Nerves, afferent and efferent, cannot beget images, nor can the brain give rise to representations—All our perception relative to action. Denial of this involves the fallacies of Idealism or of Realism—Perception and knowledge—Physiological data—Zone of indetermination—"Pure" perception—Memory and Perception.

From the study of Change we are led on to a consideration of the problems connected with our perception of the external world, which has its roots in change. These problems have given rise to some very opposing views—the classic warfare between Realism and Idealism. Bergson is of neither school, but holds that they each rest on misconceptions, a wrong emphasis on certain facts. He invites us to follow him closely while he investigates the problems of Perception in his own way.

"We will assume for the moment that we know nothing of theories of matter and theories of spirit, nothing of the discussions as to the reality or ideality of the external world. Here I am in the presence of images, in the vaguest sense of the word, images perceived when my senses are opened to them, unperceived when they are closed. ... Now of these images there is ONE which is distinct from all the others, in that I do not know it only from without by perceptions, but from within by affections; it is my body." [Footnote: Matter and Memory, p. 1 (Fr. p. 1).] Further examination shows me that these affections "always interpose themselves between the excitations from without and the movement which I am about to execute." [Footnote: Matter and Memory, p. 1 (Fr. p. 1).] Indeed all seems to take place as if, in this aggregate of images which I call the universe, nothing really new could happen except through the medium of certain particular images, the type of which is furnished me by my body." [Footnote: Matter and Memory, p. 3 (Fr. p. 2).] Reference to physiology shows in the structure of human bodies afferent nerves which transmit a disturbance to nerve centres, and also efferent nerves which conduct from other centres movement to the periphery, thus setting in motion the body in whole or in part. When we make enquiries from the physiologist or the psychologist with regard to the origin of these images and representations, we are sometimes told that, as the centrifugal movements of the nervous system can evoke movement of the body, so the centripetal movements—at least some of them—give rise to the representation, mental picture, or perception of the external world. Yet we must remember that the brain, the nerves, and the disturbance of the nerves are, after all, only images among others. So it is absurd to state that one image, say the brain, begets the others, for "the brain is part of the material world, but the material world is not part of the brain." Eliminate the image which bears the name 'material world,' and you destroy, at the same time, the brain and the cerebral disturbances which are parts of it. Suppose, on the contrary, that these two images, the brain and the cerebral disturbance, vanish; ex hypothesi you efface only these, that is to say, very little—an insignificant detail from an immense picture—the picture in its totality, that is to say, the whole universe remains. To make of the brain the condition on which the whole image depends is a contradiction in terms, since the brain is, by hypothesis, a part of this image." [Footnote: Matter and Memory, p. 4 (Fr. pp. 3-4).] The data of perception are external images, then my body, and changes brought about by my body in the surrounding images. The external images transmit movement to my body, it gives back movement to them. My body or part of my body, i.e., my brain, could not beget a whole or part of my representation of the external world. "You may say that my body is matter or that it is an image—the word is of no importance. If it is matter, it is a part of the material world, and the material world consequently exists around it and without it. If it is an image—that image can give but what has been put into it, and since it is, by hypothesis, the image of my body only, it would be absurd to expect to get from it that of the whole universe. My body, an object destined to move other objects, is then a centre of action; it cannot give birth to a representation." [Footnote: Matter and Memory, p. 5 (Fr. p. 4).] The body, however, is privileged, since it appears to choose within certain limits certain reactions from possible ones. It exercises a real influence on other images, deciding which step to take among several which may be possible. It judges which course is advantageous or dangerous to itself, by the nature of the images which reach it. The objects which surround my body reflect its possible action upon them. All our perception has reference, primarily, to action, not to speculation.[Footnote: Cf. Creative Evolution, p. 313 (Fr. p. 321).] The brain centres are concerned with motor reaction rather than with conscious perception, "the brain is an instrument of action and not of representation." [Footnote: Matter and Memory, p. 83 (Fr. p. 69).] Therefore, in the study of the problems of perception, the starting-point should be action and not sensation. All the confusions, inconsistencies and absurdities of statement, made in regard to our knowledge of the external world, have here their origin. Many philosophers and psychologists "show us a brain, analogous in its essence to the rest of the material universe, consequently an image, if the universe is an image. Then, since they want the internal movements of this brain to create or determine the representation of the whole material world—an image infinitely greater than that of the cerebral vibrations—they maintain that these molecular 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 a 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 incomprehensible action of this formless matter upon this matterless thought." [Footnote: Matter and Memory, p. 9 (Fr. pp. 7-8).]

The problem at issue between Realists and Idealists turns on the fact that there are two systems of images in existence. "Here is a system of images which I term 'my perception of the universe,' and which may be entirely altered by a very slight change in the privileged image—my body. This image occupies the centre. By it all the 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 proportion to the cause; this is what I term the 'universe.'" [Footnote: Matter and Memory, p. 12 (Fr. p. 10).] The question is, "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 well-defined 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?" [Footnote: Matter and Memory, p. 13 (Fr. p. 11).] We may style one the system of science, the other the system of consciousness. Now, Realism and Idealism are both incapable of explaining why there are two such systems at all. Subjective Idealism derives the system of science from that of consciousness, while materialistic Realism derives the system of consciousness from that of science. They have, however, this common meeting-place, that they both regard Perception as speculative in character—for each of them "to perceive" is to "know." Now this is just the postulate which Bergson disputes. The office of perception, according to him, is to give us, not knowledge, but the conditions necessary for action.[Footnote: Notre croyance a la loi de causalite (Revue de metaphysique et de morale, 1900), p. 658.] A little examination shows us that distance stands for the degree in which other bodies are protected, as it were, against the action of my body against them, and equally too for the degree in which my body is protected from them.[Footnote: Le Souvenir du present et la fausse reconnaissance in L'Energie spirituelle, pp. 117-161 (Mind-Energy), or Revue philosophique, 1908, pp. 561-593.] Perception is utilitarian in character and has reference to bodily action, and we detach from all the images coming to us those which interest us practically.

Bergson then examines the physiological aspects of the perceptual process. Beginning with reflex actions and the development of the nervous system, he goes on to discuss the functions of the spinal cord and the brain. He finds in regard to these last two that "there is 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 movements the stimulation received, the brain prolongs into reactions which are merely nascent, but in the one case as in the other, the function of the nerve substance is to conduct, to co-ordinate, or to inhibit movements.[Footnote: Matter and Memory, pp. 10-11 (Fr. p. 9).] As we rise in the organic series we find a division of physiological labour. Nerve cells appear, are diversified and 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 received 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 prepares 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." [Footnote: Matter and Memory, pp. 17-18 (Fr. p. 15).] The brain is no more than a kind of central telephone exchange, its office is to allow communication or to delay it. It adds nothing to what it receives, it is simply a centre where perceptions get into touch with motor mechanisms. Sometimes the function of the brain is to conduct the movement received to a chosen organ of reaction, while at other times it opens to the movement the totality of the motor tracks. The brain appears as an instrument of analysis in regard to movements received by it, but an instrument of selection in regard to the movements executed. In either case, its office is limited to the transmission and division of movements. In the lower organisms, stimulation takes the form of immediate contact. For example, a jelly-fish feels a danger when anything touches it, and reacts immediately. The more immediate the reaction has to be, the more it resembles simple contact. Higher up the scale, sight and hearing enable the individual to enter into relation with a greater number of objects and with objects at a distance. This gives rise to an amount of uncertainty, "a zone of indetermination," where hesitation and choice come into play. Hence, says Bergson: "Perception is master of space in the exact measure in which action is master of time." [Footnote: Matter and Memory, p. 23 (Fr. p. 19).]

In the paper read before the First International Congress of Philosophy at Paris in 1900, on Our Belief in the Law of Causality,[Footnote: Notre croyance a la loi de causalite (Revue de metaphysique et de morale, Sept., 1900, pp. 655-660).] Bergson showed that it has its root in the co-ordination of our tactile impressions with our visual impressions. This co-ordination becomes a continuity which generates motor habits or tendencies to action.

There now comes up for consideration the question as to why this relation of the organism, to more or less distinct objects, takes the particular form of conscious perception, and further, why does everything happen as if this consciousness were born of the internal movements of the cerebral substance? To answer this question, we must turn to perceptual processes, as these occur in our everyday life. We find at once that "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." [Footnote: Matter and Memory, p. 24 (Fr. p. 20).] To such an extent is this true that the immediate data of perception serve as a sign to bring much more to the mind. Psychological experiments have conclusively proved that we never actually perceive all that we imagine to be there. Hence arise illusions, examples of which may be easily thought of—incorrect proof-reading is one, while another common one is the mistake of taking one person for another because of some similarity of dress. What is actually perceived is but a fraction of what we are looking at and acts normally as a suggestion for the whole. Now, although it is true that, in practice, Perception and Memory are never found absolutely separate in their purity, yet it is necessary to distinguish them from one another absolutely in any investigation of a psychological nature. If, instead of a perception impregnated with memory-images, nothing survived from the past, then we should have "pure" perception, not coloured by anything in the individual's past history, and so a kind of impersonal perception. However unreal it may seem, such a perception is at the root of our knowledge of things and individual accidents are merely grafted on to this impersonal or "pure" perception. Just because philosophers have overlooked it, and because they have failed to distinguish it from that which memory contributes to it, they have regarded Perception as a kind of interior and subjective vision, differing from Memory only by its greater intensity and not differing in nature. In reality, however, Perception and Memory differ fundamentally.

Our conscious perception is just our power of choice, reflected from things as though by a mirror, so that representation arises from the omission of that in the totality of matter which has no bearing on our needs and consequently no interest for us. "There is for images merely a difference of degree and not of kind between 'being' and 'being consciously perceived.'" [Footnote: Matter and Memory, p. 30 (Fr. p. 25).] Consciousness—in regard to external perception—is explained by this indeterminateness and this choice. "But there is in this necessary poverty of conscious perception, something that is positive, that foretells spirit; it is, in the etymological sense of the word, discernment.'" [Footnote: Matter and Memory, p. 31 (Fr. p. 26).] The chief difficulty in dealing with the problems of Perception, is to explain "not how Perception arises, but how it is limited, since it should be the image of the whole and is in fact reduced to the image of that which interests you." [Footnote: Matter and Memory, p. 34 (Fr. p. 29).] We only make an insuperable difficulty if we imagine Perception to be a kind of photographic view of things, taken from a fixed point by that special apparatus which is called an organ of perception—a photograph which would then be developed in the brain-matter by some unknown chemical and psychical process. "Everything happens as though your perception were a result of the internal motions of the brain and issued in some sort from the cortical centres. It could not actually come from them since the brain is an image like others, enveloped in the mass of other images, and it would be absurd that the container should issue from the content. But since the structure of the brain is like the detailed plan of the movements among which you have the choice, and since that part of the external images which appears to return upon itself, in order to constitute perception, includes precisely all the points of the universe which these movements could affect, conscious perception and cerebral movement are in strict correspondence. The reciprocal dependence of these two terms is therefore simply due to the fact that both are functions of a third, which is the indetermination of the Will." [Footnote: Matter and Memory, p. 35 (Fr. p. 29).]

Moreover, we must recognize that the image is formed and perceived in the object, not in the brain, even although it would seem that rays of light coming from a point P are perceived along the path of the sensori-motor processes in the brain and are afterwards projected into P. There is not, however, an unextended image which forms itself in consciousness and then projects itself into the position P. Really, the point P, and the rays which it emits, together with the retina and nervous elements affected in the process of perception, all form a single whole. The point P is an indispensable factor in this whole and it is really in P and not anywhere else that the image of P is formed and perceived.[Footnote: Cf. Matter and Memory, p. 37 (Fr p. 31), also paper entitled Notre croyance a la loi de causalite in the Revue de metaphysique et de morale, 1900, p. 658.]

In the field of "pure" perception, that is to say, perception unadulterated by the addition of memory-images, there can arise no image without an object. "Sensation is essentially due to what is actually present." [Footnote: Le Souvenir du present et la fausse reconnaissance, p. 579 of Revue philosophique, Dec., 1908; also L'Energie spirituelle, p. 141 (Mind-Energy).] Exactly how external stimuli, such as rays of a certain speed and length, come to give us a certain image, e.g., the sensation "red" or the sound of "middle C," we shall never understand. "No trace of the movements themselves can be actually perceived in the sensation which translates them." [Footnote: Time and Free Will, pp. 34-35 (Fr. p. 26).] We only make trouble by regarding sensations in an isolated manner and attempting to construct Perception from them. "Our sensations are to our perceptions, that which the real action of our body is to its possible or virtual action." [Footnote: Matter and Memory, p. 58 (Fr. p. 48).] Thus, everything happens as if the external images were reflected by our body into surrounding space. This is why the surface of the body, which forms the common limit of the external and internal, is the only portion of space which is both perceived and felt. Just as external objects are perceived by me where they are, in themselves and not in me, so my affective states (e.g. pains—which are local, unavailing efforts) are experienced where they occur, in my body. Consider the system of images which we term the "external world." My body is one of them and around it is grouped the representation, i.e., its eventual influence on others. Within it occurs affection, i.e., its actual effort upon itself. It is because of this distinction between images and sensations that we affirm that the totality of perceived images subsists, even if our body disappears, whereas we cannot annihilate our body without destroying our sensations. In practice, our "pure" perception is adulterated with affection, as well as with memories. To understand Perception, however, we must—as previously insisted upon—study it with reference to action. It is false to suppose "that perception and sensation exist for their own sake; the philosopher ascribes to them an entirely speculative function," [Footnote: Matter and Memory, p. 311 (Fr p. 261).] a proceeding which gives rise to the fallacies of Realism and Idealism.

It has been said that the choice of perceptions from among images in general is the effect of a "discernment" which foreshadows spirit. But to touch the reality of spirit, we must place ourselves at the point where an individual consciousness continues and retains the past in a present, enriched by it.[Footnote: See Chapter VI on la duree. Time—True and False.] Perception we never meet in its pure state; it is always mingled with memories. The rose has a different scent for you from that which it has for me, just because the scent of the rose bears with it all the memories of all the roses we have ever experienced, each of us individually.[Footnote: Time and Free Will, pp. 161-162 (Fr. p. 124).] Memory, however mingled with Perception, is nevertheless fundamentally different in character.[Footnote: Le Souvenir du present et la fausse reconnaissance, Revue philosophique, Dec., 1908, p. 580; also L'Effort intellectuel, Revue philosophique, Jan., 1902, p. 23; L'Energie spirituelle, pp. 141 and 197 (Mind-Energy).] "When we pass from 'pure' Perception to Memory, we definitely abandon matter for spirit." [Footnote: Matter and Memory, p. 313 (Fr. p. 263).]