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Chapter 8 - (Part 2)

181. The soul, therefore, by means of shaped sensations, perceives shapes first and foremost as limits of the body already felt by the fundamental feeling. The only shapes it feels are its own.

The wisdom of the Creator established the wonderful harmony between acquired, incidental feelings and the first, fundamental feeling. Shapeless feelings were to be simple alterations and modifications of the fundamental feeling, not completely new feelings. Shaped feelings were to reveal forms and shapes serving as boundaries and limits to the fundamental feeling which they would better delineate and define, and were to possess other relationships determined by the purposes they were to serve; they were not to be independent of the fundamental feeling or of one another. We must now carefully examine and reflect on this harmony and law of relationship which the Creator has established between the fundamental feeling and incidental feelings.

182. Let us suppose that a human being has only the fundamental feeling. If this person were touched successively over the whole surface of his body by a small object, a piece of metal for example, he would successively experience many surface-extended sensations situated at the extremity of his corporeal-fundamental feeling. The sensations would present (by means of the faculty of sense-retention) shapes which, relative to each other and to his fundamental feeling, are distributed according to a definite order. Relative to each other, they are so positioned that they constitute a continuous surface-covering in all directions, that is, a surface enclosing a solid. The shape they assume is precisely what we call the human body. However, relative to the fundamental feeling, the sensations define the limits in such a way that the feeling subject feels that his corporeal-fundamental feeling receives a previously unknown determination which now circumscribes him in a portion of space.

183. It may be objected that this is not surprising because, evidently, when the body is touched in all its extremities, the sensations must take place there, and thus be contiguous, while encompassing and determining the fundamental feeling. But this only repeats popular ideas of the body and fails to recognise that my suggestion of a piece of metal tracing the surface of the body entailed the use of everyday language in order to make myself understood. Our feeling subject, however, is ignorant of metals or surfaces; he simply feels himself as a feeling subject modified by something different from himself and acting upon him. He must wonder (if he thinks at all) at the harmony between the modifications he experiences, and must say to himself: `These feelings are not the result of chance, but of great wisdom. The unknown agent acts upon me according to a constant law of harmony and balance.'

As a result of these harmonious modifications of the fundamental feeling, the sentient subject 1. perceives the shape of the space occupied by his fundamental feeling; 2. invents the words shape, space or extension, surface and body; 3. perceives a surface-extended agent, which he calls metal; 4. perceives the motion of an agent which gives rise to partial sensations contiguous to each other.

Reflection on his feelings will certainly lead him to express himself in this way. For example, he will say that a piece of metal has moved over all the extremities of his body. Despite the fact, however, that he has distinguished, named and expressed different ideas, his initial wonder caused by the conformity and union of so many sensations need not be extinguished. The phenomena remain subject to the same wonderful laws, and their author still exists. Coining words like metal and body, does not mean I know what metal or body is. I have simply noted and described the apparent mechanism of an action, not the real forces involved in it, nor the wise principle legislating for them. In a word, I have not found a sufficient reason for the relative position of so many different feelings.(82)

184. Through force of habit we look at what nature presents, but forget its wonderful teaching power. There seems no reason to ask ourselves why things are done in one way rather than another. We see them as they are, and that is sufficient. In this case, the shape of our bodies is formed by a complex of feelings produced by sensations of touch. The sensations are collocated in such a way that relative to each other and to the fundamental feeling they describe the limits of the fundamental feeling. We do not ask ourselves why this is so because there is no apparent, intrinsic reason for it, as I shall explain.

Let us suppose that the piece of metal touches the whole surface of my arm. No intrinsic reason requires that I have a circular sensation or, more correctly, that I have a complex of sensations which, granted I retain them all, trace a circle for my sense-faculty. There is no reason why different modifications of my fundamental feeling could not arouse in my feeling principle a straight, rather than a curved, sensation, or a flat surface rather than a curved one. This possibility becomes obvious when we consider that the law which locates sensation at the extremity of the fundamental feeling applies solely to touch; the other senses have their own laws, and amongst these we must carefully consider the law that applies to the space perceived by the sense of sight.

If we consider only what this sense has in common with touch, the position of the visual sensation must be in the retina of the eye and occupy the various, tiny planes in which the different points of the retina can be moved. But if we consider sight as a special sense, its sensations, in common with touch, are spread over a surface. Visual surfaces, however, do not take their relative positions according to the law determining the position of tactile surfaces. Unlike tactile surfaces, which appear at the limits of the fundamental feeling where the stimuli are applied, visual surfaces do not appear in the planes determined by the nerve extremities which end in the retina of the eye. They are subject to quite a different law. If they followed the law of touch, each eye, when looking at a luminous object, would see a little surface in a different plane, because the rays from an object, striking the nerve extremities of the eyes looking directly at the object, fall upon two surfaces which are not in the same plane but inclined at an angle to each other. This angle varies according to the distance of the object, and therefore according to the acute or obtuse angle formed by the optic axes. If the visual surface adhered to our body, as a tactile surface does, it would necessarily divide into several surfaces whose location would depend on whether our gaze were fixed on a single, close or distant point, or on two different points. However, both eyes show only one visual surface, perfectly flat and determined by its own special law (cf. 115, 169).

185. According to what we have said, this law consists 1. in all the objects being seen in a flat surface whose position is given by nature; 2. in the alignment of the optical axes which determines the way the external objects are carried on to this surface of given position: if the axes are parallel, each luminous object in which they terminate is felt individually on the visual surface. If the axes intersect to form an angle, the object situated at the apex of the angle appears on the visual surface as a single object. But how can this apex, whose distance varies, influence the eyes, if it is outside the eyes? And in such a way that the feelable object situated at the apex appears as a single object to the soul in the visual screen of given position? It is impossible for light rays, passing from an object and striking the retina of each eye, to undergo a refraction after striking the retina according to certain laws of refraction which would determine that the rays, or the movements initiated by the rays, are carried on to the same internal screen and in the same place.

Neither the visual surface in its position given by nature, nor the way in which the sensations of both eyes are initiated and distributed in the surface, can explain first how a single object becomes two objects, and then how two objects merge into a single sensation, and finally how a single sensation corresponds to two impressions made by the light on the eyes. The only explanation is that the surface has a relationship with external space and that, as a necessary condition of this relationship, space is present in feeling (cf. 164, 172).

It is clear, therefore, that this visual wall, a wall of the soul, as it were, is a surface located by the Author of nature in pure space. The process he employs differs radically from that used to locate the walls or tactile surfaces at the extremity of the fundamental feeling. But the law by which tactile sensations are arranged in surfaces to form the boundary of our body is no less extraordinary than the law that requires visual sensations to be placed in a flat, uniform surface within pure space.(83) The two laws are equally admirable.

186. We continue to consider how sensations are composed. First, in the case of sensations of touch, we note at once that when the piece of metal in our example moves over the whole surface of the body, the sensations it produces are successive, not simultaneous. Consequently the sensations alone cannot give us the limits of our fundamental feeling; they need a retentive faculty in the soul, which either unites successive sensations or at least extracts a single message from many. The continuity of position of the sensations, therefore, is not determined by the soul but is inherent in the sensations themselves, whose mode of existence is not only extension but also a position relative to each other in solid space.

187. When examining the sensation produced by the piece of metal passing over our skin, we have to distinguish very carefully between the sensation itself, which consists wholly in a modification of the fundamental feeling (enabling the feeling subject to feel only a partial mode of this feeling), and the perception of the external agent (which we later call `a piece of metal'). However, the sensation of our body and the perception of the external body have quantity and extension in common. For example, if we have two simultaneous sensations, we deduce that the agents must also be two, that is, that two pieces are touching our skin. If the extension of each of the two felt surfaces is a square centimetre, we say that each piece of metal has an extension of one square centimetre.

188. We must also take into account the passivity proper to sensation, and the activity proper to an external agent: an agent is not perceived unless its activity is felt in our passivity.

189. Moreover, we associate with the external agent what in reality belongs to our feeling. We say, for example, the metal is cold, although `cold' is not a property of the metal, but simply our sensation. The same is true of all the secondary properties of bodies. This kind of confusion gives rise to popular error, although we can allow bodies their secondary properties in order not to introduce unnecessary difficulties into our argument. We shall therefore call bodies enveloped by secondary qualities ordinary bodies. If they are also animal bodies, we shall continue to call them anatomical bodies.

190. Nevertheless, we must be careful to maintain the distinction between the modification of the fundamental feeling, which is properly called sensation, and the perception of an external agent, which consists entirely in the disturbance experienced in the modification of our fundamental feeling, where the modifying energy, alien to the feeling subject, is clearly evident.

We have called sensations subjective phenomena, and perceptions of external agents extrasubjective phenomena whether the external agents are considered in their genuine qualities or as ordinary bodies.

191. We must now see how by means of touch the soul perceives an extension greater than that presented by the limits of the soul's fundamental feeling.

I say `perceives' although `perception' is not altogether correct. We accept unlimited space as the constant term of the fundamental feeling, and find that as such it does possess indeed the nature of `term' of feeling. Space, however, does not begin to be perceived properly speaking (that is, to be distinguished as foreign to the feeling subject) except in the perception of bodies and as modes of bodies. It was under this aspect that we considered space in The Origin of Thought.

192. We said that a space larger than that occupied by our body can be perceived only by means of the sense of movement. As long as we imagine the feeling subject at rest, it could never, even if touched by foreign bodies, be touched in an extension greater than that presented by the limits of its fundamental feeling. Hence, such sensations could never make it feel a greater extension. In order to supply for this limitation of the fundamental feeling, the wisdom of the Creator endowed the feeling subject with movement. But movement is a phenomenon that does not attract particular attention; it is so ordinary and natural that we give no thought to it. Nevertheless, careful reflection reveals how extraordinary it is.

193. I shall confine myself solely to the action of touch. Let us suppose that our feeling subject places his extended hand on the edge of a table and follows the edge with a continuous motion to the opposite edge. It is certain that his moving hand cannot have a sensation extending beyond his hand. The only way his hand can feel an extension greater than itself is by feeling successive sensations, each the size of the extension of his hand. But this is not sufficient, because it could be merely the same sensation repeated. Indeed, if his hand remains motionless and is touched successively many times, the extension it feels will be no greater than that presented by the hand on contact with external agents. Moreover, the feeling principle, in addition to feeling many successive sensations in the surface where its fundamental feeling terminates, would have to know in some way that the surface-extended agent which first touched it (in our case, the part of the table touched by the palm of the hand) is not the second agent, not the part of the table touched by the hand when it moved. The feeling principle would also need to know that these two agents, and all the successive agents, are continuous and form a single surface extension.

The soul comes to know all this by means of a wonderful law which governs the modification of its feeling act. According to this law the soul can change both the space it occupies and the partial limits of its corporeal fundamental feeling: this is motion. In fact the movement of the hand is only `a change of place of the limits of the corporeal fundamental feeling', and such a change presupposes the solid space given to the soul by nature. The change also requires sensuous retention of the limits of the preceding space. But even the union of the preceding and following limits by sensuous retention would be insufficient to constitute a continuous space for the soul if the change from one limit to another took place by leaps and bounds, so that, for example, the feeling of my arm when moved from pointing east to pointing south would not be extended in the quadrant between the two points. There is no contradiction in conceiving the possibility that feeling is subject to such a law. But if this were so, the soul would never feel a surface greater than that presented by its own limbs, while each felt surface would be separate and totally independent. Thus, if the surfaces were equal, they would be confused in the soul, identified like the sensations of the two eyes, and distinguishable only by their inequality.

194. For the feeling principle to present a surface greater than that given by the limits of the fundamental feeling, 1. the limits of the corporeal fundamental feeling must be variable, that is, they must circumscribe another portion of space (space is the term of the fundamental feeling); 2. the variability of the limits must be subject to the law of continuity, so that the new limits of the corporeal fundamental feeling are in a position of continuity with the preceding limits; 3. the change of limits and the law of continuity must be feelable, that is, within a space felt by nature (if the corporeal fundamental feeling, which has changed shape and limits, did not feel the change or the manner of the change, it could never inform the soul, as we know it does, of the extension which exceeds the limits of the body); 4. the soul must retain the limits it first felt and unite them in space (which is the term of feeling) with limits felt afterwards; otherwise, the soul could never form for itself the large extension of the table under discusion. We call this faculty of the soul sensuous retention.(84) According to its capacity for sensuous retention, the feeling subject, granted movement, can perceive how much a corporeal extension exceeds its own body.

195. We have already explained how sight, using signs of extraordinary precision and detail, wonderfully helps touch to indicate a variety of objects (cf. 169).(85) There is nothing more wonderful than the harmony of these two senses. Sight sensations have no similarity whatsoever to touch sensations, and visual objects are essentially different from tactile objects. Nevertheless, although the objects differ in size and in everything else, we accept them as identical simply by the analogy of their forms and the amazing correspondence of shape that exists between the sensations of sight and touch. The illusion originates in the fact that the size of the objects given by each of the two senses does not have a common measure: tactile objects are measured by touch, which is unable to measure visual objects; and visual objects are measured by the eyes, which cannot measure tactile size by comparing it with the size of its own objects. Thus the difference of size remains unknown to our feeling; it is revealed only by intelligence after careful reflection.(86)

196. Sight sensations, however, offer further assistance for perceiving an extension greater than that of our own body. Despite its tiny size, visual sensation corresponds not only to a single sensation of touch, but to the innumerable touch sensations produced as a result of great movement. Moreover, the eyes enlarge their sensation both with the movement of the fundamental feeling and when they are kept fixed on a scene which changes before them, provided the scene is varied and not entirely uniform.(87)

197. We have seen how the feeling subject comes to know 1. the limits of the fundamental feeling and the size of the space occupied by this feeling; 2. the spaces and external bodies that limit the fundamental feeling (as a result of the shapes presented by touch and sight).

We must, however, always keep in mind the difference between the perception of external bodies and the perception of our own. The perception of external bodies was explained by the extrasubjective agents' modifying the fundamental feeling; the perception of our own body was explained by the subjective modification of the fundamental feeling. The two explanations are so different that if we perceived our body only subjectively, it would be impossible to believe that it was of the same nature as external agents. We would have called it simply `fundamental feeling', or at most `extension of the fundamental feeling', but never `body'. But we saw that this being, although passive to external agents, is active in its own turn. It becomes an external agent itself, maintaining identical size and shape in both active and passive states. We cannot doubt, for example, that our hand, which we feel subjectively, makes itself felt extrasubjectively: it can be touched and seen like any other thing devoid of subjective feeling. When we touch our hand, an extended agent is felt in exactly the same surface that forms the limit of our fundamental feeling. We can easily demonstrate this by placing one hand on the other, when each naturally becomes an agent and recipient. The surface of one hand in which a feeling is aroused is the same surface acting on, and arousing a feeling in, the other hand.(88)

Our body, therefore, has the same active energy and the same laws of extension as any other body, and is rightly called `body' in common with all external bodies. However, it has something else: the space it occupies is the exact space of the fundamental feeling and its modifications.

198. The fundamental feeling is of course passive, and therefore the opposite of the agent which produces it. Nevertheless, because it occupies the same space and dimensions as the body, it melds with the body, which we then call sentient and living.(89)

199. We must carefully distinguish the two ways of considering our body. They constitute two series of facts which have only extension in common, and presuppose two beings, as it were, in the same extension.

Our investigation into the relationship between the two beings or series of facts must ignore theory and a priori conceptions, and be guided solely by attentive observation. Our aim is to deduce the harmonious laws that unite the two kinds of phenomena, subjective and extrasubjective, which may in some way be seen as parallel, although they cannot be considered united as cause and effect; this is excluded even by the anomalies present in their parallelism.

200. For the sake of clarity in touching upon the law of the relationship between the two series of phenomena, and their parallelism and its anomalies, I call our body `extrasubjective body' in so far as we know it as an external agent, that is, in the extrasubjective way we know all foreign bodies. I call `subjective body' the extension we feel subjectively, as presented to our soul in our feelings. However, I also consider the subjective and extrasubjective body as two entities having the same limits and, generally speaking, the same extension.

201. I must point out immediately that the extrasubjective body is either real, or is phenomenal, popular and anatomical.

Our real extrasubjective body is known by us simply as an energy which modifies our soul, giving it extended sensations (as a sensiferous principle) and modifying the other energies capable of modifying our soul.

The popular or anatomical extrasubjective body is the same energy considered in its indirect, not its direct, action on our soul, and clothed with the so-called secondary qualities of colour, smell, etc. The body, considered as directly acting on our soul, cannot be an object of anatomy or of our exterior senses, and is known only in a direct way by the feeling it produces.

202. Following our argument, we say that such energy can be considered clothed with secondary qualities not because the qualities are part of the energy but because some element causing them must be present in the energy. Thus, when we speak of a white body, we do not intend to attribute whiteness, which is a sensation, to the body. We are attributing a power which, granted certain conditions, produces whiteness in us. Whiteness is understood as the sign of the power of this quality, whatever it may be.

203. The relationship to be investigated, therefore, is that between our ordinary, anatomical, extrasubjective body and the subjective body or, more accurately, between the extension of the anatomical body and the subjective extension in which feeling terminates. This relationship is at the core of our investigation and the subject of all the great controversies.

204. The relationship, however, between the corporeal feeling and the body acting directly on the soul is simple and unique, without any possible anomaly in its parallelism. Feeling itself makes known the agent causing the feeling, so that the body, by the very fact of this action, becomes the cause of the feeling. This observation has led me to ascertain, without doubt as far as I can see, reciprocity between soul and body.(90)

If, however, instead of considering the body in its essential act, where its nature is given in the very fact itself, we turn our attention to the ordinary, anatomical, extrasubjective body, the case is quite different. Our task now is to investigate the law of the relationship which unites this body to the extension of the corporeal feeling, that is, to the subjective body.

205. The human mind, impatient and desirous of reaching immediate conclusions, always prefers to guess about nature rather than observe it. Thus, in the question we have proposed, our first thought is that the law of the connection between the extension of the ordinary or anatomical extrasubjective body (the only body our mind usually considers) and the extension of the corporeal feeling simply states that `to every change in the extension of the ordinary, extrasubjective body there corresponds a feeling in the same place'.

206. A person who makes this kind of judgment has already progressed beyond the first stage, despite his mistake. In the first stage anyone could have confused the impression or change in the ordinary, extrasubjective body with the feeling accompanying it - the childish error, one might say, of materialists. But the person who has made some progress distinguishes the impression or change taking place in the anatomical body from the subsequent sensation, although he believes that `feeling is always joined with identity of place to the impression or change in the anatomical body'.

207. Now, because the absolute motion of our body is in itself totally unfeelable,(91) the question is reduced to examining whether this opinion is true in the case of the relative motion of the parts composing our body.

208. The man in the street does not doubt the truth of the opinion we are examining. Hence, granted this common error which springs from excessive generalisation, Haller's discovery was considered of great importance. He demonstrated that a corresponding feeling was not always present in the place where parts of the body were touched and moved; only the nerves were the proper seat of feeling. Such a discovery was contrary to the opinion that sensation must accompany every change of place in the parts of the anatomical body.

209. Despite Haller, the error was maintained not only by people in general but also by the most learned naturalists, although the latter limited it to the nerves. The well-known anatomist, Felice Fontana, firmly held that a sensation took place where a nerve was touched. `Feeling,' he said, `is a quality of the nerves and cannot exist where there are no nerves. We can have clear ideas about what we are trying to understand, only if we realise that extension, weight, and impenetrability of bodies (qualities proper to bodies) cannot be found separate from bodies themselves.'(92) Such words presuppose as certain that `feeling is a quality inherent in bodies'. But the bodies mentioned are only ordinary bodies, which do not feel, but cause feeling, although only indirectly and as acquired feeling. Popular opinions of this kind are maintained with great facility even by those who, like Felice Fontana, firmly aim to be guided in everything by accurate, logical observation.

210. It is important therefore to demonstrate the falsity of the claim that to every movement produced in a part of the ordinary, anatomical body there corresponds a new feeling in the same part and place. Nor is it true that the extension with which feeling is endowed is modified in a way fully parallel with, and corresponding to the modification of the ordinary, anatomical body. To show this, we begin with an observation on the very phenomenon used to support the popular misconception we refute. For example, when a sharp point is applied as a stimulus to the external surface of our body, we feel pain at the spot where the point is applied. From this we generally conclude that the feeling happens in the part of the body which has been modified and touched. We also consider the conclusion applicable to all parts of the body (or at least those considered to have feeling) and to every kind of stimuli.

211. But if we consider this phenomenon of external touch carefully, the opposite of what we think proves to be the case. Everybody accepts that there is no evident sensation unless the movement of a nerve touched at its extremity reaches the brain. If a finger is pricked, the movement does not remain there alone, but is communicated along the arm to the brain. Now, if the opinion we are refuting were true, we should feel the pain not only in the finger but in the whole nerve as it is moved and modified throughout the length of the arm to the brain. But this does not happen. Thus, the modification of the anatomical body and the new feeling it arouses in the soul are different things. Although both present an extension, they do not present the same extension; nor is the extension modified according to the same laws. In the example given, the extension of the modification of the nerve follows a line stretching from the finger to the brain, but the feeling is concentrated in a point, at the extremity of the finger.(93)

212. We should not be surprised, therefore, at the phenomenon presented by those who have had an arm or leg amputated: they sometimes claim to feel pain in the extremities of the limb, which they have lost.(94) Such a fact would indeed be a source of wonder if it were true that the affected part of the anatomical body corresponded at every point to the location of the feeling. But we cannot say this, and if we wanted to say it, we would first have to identify it by a very attentive observation rather than imagine it or argue to it a priori. Hence, we believe that the laws of the relationship between these two kinds of location demand deep, careful study.

213. There is in fact no difficulty in indicating similar phenomena, in which the location of the feeling corresponds not to the movements of the parts but to the external surface of the body. Diseases are a good example: it is not uncommon in the case of fevers of the nerves for internal parts to be inflamed while the extremities are cold.(95) Sometimes the whole surface of the body is seized by cold, as in the case of the fever which antiquity called algida.(96) At other times a feeling of warmth covers the whole external surface, while the sick person feels cold internally. In these cases where the feeling of warmth and cold is situated in the skin, we cannot believe that the movement of the nerves preceding the cold in the anatomical body is restricted only to the skin. The body of the sick person is not touched externally by anything hot or cold, which might warm or cool it. The feeling of cold and warmth located in the skin comes from internal movements of the nerves. But these movements are not felt, at least not with a cold or warm sensation located solely in the surface extension.(97) Sometimes the cold in the skin is the effect of the internal action of poisons, like the sap of the cinchona or the poison of a rattlesnake bite. We have to conclude therefore that the divine Author of the human race has in his wisdom established the following law: `corporeal feeling (given certain circumstances) is principally referred to the surfaces of the body'. By this wonderful law human beings are able to perceive, as I have said, shaped spaces which are necessary for the development of their understanding and for daily life.

214. It used to be thought that the vital principle resided at the centre of the animal. For a long time this opinion prevented physiologists from devoting to the surfaces of the body all the attention that modern thinkers have given.

215. Professor Santarelli called these surfaces `organic levers of life'(98) - an extraordinarily apposite phrase, I think. In one of his writings he enumerates the different classes of sensations, and says: `All these sensations take place where the nerves begin, that is, in both the external and internal surfaces of every cavity and vessel. The movement of the nerves therefore begins at these apexes, from which it spreads to all the parts, giving rise to the harmony and accord which is health.'(99)

216. The intestinal canal can be considered as a continuation of the skin. The covering of the larynx, trachea and bronchial tubes is also considered to have the same texture. If the different kinds of sensations we experience along this passageway are not shaped, as is the case with those referred to the skin, we must bear in mind that the precise position of the sensations situated in the cutaneous surface depends largely on two conditions which cannot be present relative to the internal surface of the intestinal canal. The conditions are: 1. the use of sight, which is a sense eminently adapted for outlining or shaping things and an incredible aid for perceiving the positions, relative to the whole body, of the external stimulus arousing the sensation and of the sensation joined to the stimulus; 2. the use of movement, especially of the hands, with which we can touch successively all the parts of the external surface of our body, become fully acquainted with our body in a practical way, and are thus able to note precisely the position of sensations. Noting the position of sensations means knowing the place where they are situated relative to all the other parts of our body. In order to be able to state where we feel, we have to perceive all the parts of our body. And the only parts we can feel totally are the external surfaces, precisely because they are all perceived together by our eyes, and by our touch which can be applied to all the parts successively.

217. Thus there is a difference between a sensation with its real seat in a determined place and limb, and our adverting and telling ourselves where we feel respectively these different parts of our body. We can feel in a part without knowing which part, because we lack this awareness. For example, if we had never seen or touched the surface of our body, and had as our first sensation the prick of a needle in our arm, we would certainly feel in the spot where we had been pricked. But we would not be able to know, advert to, or state to ourselves the distance of the sensation from our head, feet or hands, etc., because we would not yet have perceived the size, shape and respective position of these parts. I have already pointed out that if we sit for a long time in darkness without moving, we lose awareness of the way we have disposed our hands and feet, so that we cannot say how they are folded relative to each other. A friend of mine was once sitting in church next to an old man who had the habit of crossing one leg over the other. On this occasion the man made a mistake and crossed his leg over the knee of my friend, who made no move. Only when it was time to leave, did the old man become aware of what he had done.

218. When speaking about the position of sensations, we have to distinguish two very different cases. The first, absolute position, is inherent to all sensations that have position. The second, relative position, is not inherent to individual sensations but deduced from the relationship of place between many sensations. This deduction is carried out by mental advertence rather than feeling.

The relative position of sensations is known only by experiencing all the parts of our body. This experience, which helps us determine the relationship between the subjective feeling and our body perceived extrasubjectively, is due particularly to the two senses of touch and sight, as I have said.

219. The absolute position of sensations (and its relationship with the position of movements produced in the anatomical, extrasubjective body) offers many phenomena that would need careful study, in addition to those I have already mentioned. Here I shall mention only a few in the hope that others will be encouraged to consider the matter more deeply.

Cold, by obstructing the functions of the stomach, can sometimes cause convulsions in people subject to such attacks. The convulsive movements can be preceded by exceptional cold in the neck, but the cold certainly has its origin in the stomach, even if the place of the sensation is the lower part of the head. Pains in the head are common with gastric fevers. The stimulus therefore is very often in the stomach nerves, but the sensation phenomenon reveals itself in the brain. Hunger, when felt, produces an intense sensation only in the cardiac, although all abdominal parts involved in digestion are affected. The explanation could be a possible nerve communication between the cardiac and the brain, but even so the communication is not felt. My observation, therefore, that the place of sensation is different from that of movement, remains valid. Bichat says:

220. Physiologists unhesitatingly posit the nerves as the seat of feeling. They then find it inexplicable that certain, apparently nerveless parts of the body seem, under certain conditions, to have feeling. Ligaments irritated by an acid or a concentrated alkali or by some instrument do not give any feeling, but when scratched or torn cause intense pain. Cartilages and serious membranes, which appear insensitive in their natural state, cause very sharp pain when inflamed - I have already mentioned the painful caruncle of Professor Scarpa (cf. 91). Fontana suggested that these apparent pains in parts devoid of nerves could be explained either by the communication of movement to the neighbouring nerves or by the disturbance of the fluid which he thought filled the basic nerve canals and which he believed he had undoubtedly seen under very powerful microscopes. But it would be difficult to believe that the fluid disturbed by the nerves had feeling independently of the transmission of its movement to the brain because the movement could not conceivably propagate itself outside the vessels.(101) In the other case the movement communicated to the nerve would explain the origin of the pain, but not how the seat of the pain is outside the nerve.

221. Dumas sought to explain the phenomenon by saying that the nerves possessed the property of radiating the feeling and extending it to the parts devoid of nerves. Many have used the expression after him. This, however, would be a case not of radiating the feeling but of projecting it over a great distance, because in fact where there are nerves, there is no feeling, and contrarily, where there are no nerves, there is feeling. Is it not preferable to say that subjective feeling is not inherent to any part of an extrasubjective body but may occupy different places at various times, according to laws which must be deduced by patient observation? It would be impossible to find, in the modifications and movements of the anatomical body, any identity between place and extraordinary sensations such as those of the auras of a person subject to epileptic fits.

222. We must also distinguish the position of certain sensations from the extension with which they are endowed. For example, sight sensation has extension but no position in its phenomenal part (cf. 173). A coloured surface is perceived, but, as we have already indicated, the soul does not assign any place to the surface, nor refer it to any part of its own body. In fact, if the soul referred sensations of light to the retina, the objects would undoubtedly be double because referred to the two retinas. Because the sensations are not referred to any part of the body, the surfaces can be identified in space, and the objects of sight transported outside us, making the coloured surface of the eye like a stage, whose scenery depicts the objects of touch.

223. Finally, there are feelings entirely devoid of position and extension; smell, sound, colour and taste are evidently of this kind.

224. I do not doubt that these sensations in so far as they possess something in common with touch have a position in our body. However, the quantity of the tiny sensations from which they result, and the inequality of the impact of a stream of particles on the nerve endings, prevent them from presenting a clearly defined extension.(102) Thus, if the light is too strong for our eyes, or disease has made our sense of sound (or sense of smell, in the case of women after childbirth) extremely acute, an unpleasant sensation is associated with the unextended, phenomenal sensation. This unpleasant sensation has position by being referred to the place of the affected organ, which then acts like the general sense of touch.

225. Consequently we must distinguish: the quality, extension and position of sensations.

226. The quality of sensations requires different conditions from those necessary for their extension. Relative to the anatomical body, the quality varies according to 1. the varying construction of the organs, 2. their healthy or diseased state,(103) 3. the degree of natural vitality, and 4. the accidental stimuli activating the vitality in different ways.(104)

227. I conclude these comments on the laws of the relationship between the changes in our anatomical extrasubjective body and those in our subjective body by noting that this relationship can never consist in a connection of cause and effect. It consists solely in concomitance or parallelism, in two accompanying series of phenomena, as it were, without either being the cause of the other. What I have said about the ordinary, anatomical, extrasubjective body clearly indicates that the phenomena of this body cannot be the cause of the subjective phenomena. The extrasubjective body does not present us with what it really is, but only with the effects of an agent on us, effects which depend in great part on the nature of the subjective body and our soul. Hence the cause of both series of phenomena must be sought in an unknown principle, that is, the real body, the sensiferous principle, which truly acts in our soul, producing the subjective phenomena and subjective body, and then modifying this subjective body. With this new action or impact on the subjective body the sensiferous principle produces the extrasubjective phenomena and the ordinary body. Because these phenomena are so vivid, distinct, limited, shaped and constant, they generate an overriding, almost invincible persuasion in us that together they constitute the only corporeal reality.

228. We can easily understand, therefore, why the interaction of the soul with the body fruitlessly exercised the greatest minds, and was ultimately considered inexplicable.(105) Only the ordinary, extrasubjective body was considered. Consequently, the cause of the subjective phenomena was sought where it could not be found. The truth is that the ordinary, extrasubjective body is not and cannot be the cause of the subjective phenomena or feelings.

229. As a corollary of this teaching, we may affirm that the principle posited by Gall, Spurzheim and other phrenologists, `certain forms of the brain correspond to certain dispositions of the soul', cannot be accused of materialism or rejected a priori.

Experience alone must identify the laws of the relationship between the forms of the anatomical body, the feelings and the dispositions of the spirit. But whatever these laws may be, they will never constitute a connection of cause and effect. Such a union is seen to be impossible and absurd as soon as we ask `what in reality are the brain, fissures and protuberances'. The question cannot be answered unless we acknowledge that they `are simply effects and phenomena produced in our touch and sight (or in our imagination which reproduces similar sensations) which do indeed suppose an unknown agent. But it is absurd and even childish to put our faith in them by changing the phenomena into absolute reality and entity'. The materialists' error consists precisely in their belief that the two series of subjective and extrasubjective phenomena are cause and effect. Materialists are not satisfied with the fact, which presents the phenomena as concurrent, or with serious reflection, which tells us that their only possible connection depends upon parallelism and nothing more.(106)

Notes

(82) It is clear that if the various shaped and non-shaped feelings experienced by a feeling principle were all isolated from each other, we could not form with them the notion of a fixed, determined entity, like the popular notion of body. To acquire this notion and the persuasion that bodies subsist, and therefore to be able to name them, the union of the surfaces or forms that we feel must clothe and limit a solid extension in every direction; otherwise we would have only independent surfaces. This distribution of the sensations of surfaces is particularly necessary for forming the concept of our own body; the surface-covering must enclose the fundamental feeling entirely, and thus constitute a living solid.

(83) The flat surface of sight, however, has a certain intrinsic relationship with the total feeling of our body. The relationship makes us aware that the visual surface is in front of us, not behind us, nor anywhere else.

(84) This is a function of the animal unitive force, as we shall see later.

(85) OT, 907-922.

(86) To understand better what I am saying, let us suppose that the nerve membrane, sensitive to light, instead of being extended solely in the middle of the pupil, extends over the whole of our body, covering it entirely. Only in this case could we compare the absolute size of the sensation received in the retina with the size of our whole body, because the whole body would be sensitive to the same stimulus of light. On the other hand, if optic sensitivity is restricted to the pupil, the whole visual world is restricted to the pupil while, relative to this way of feeling, the rest of the body would apparently be non-existent. It is impossible, therefore, to compare the size of the retina with the size of our body, which is not felt, or to know the difference between the two.

(87) I do not deny, however, that something similar can happen in touch, provided the uniformity in the sensations is not interrupted. For example, if a perfectly smooth rod is drawn across a part of my arm, I cannot know the length of the rod. The sensation is constantly equal, and therefore I cannot be certain whether the same agent is acting all the time or the agent is continually different. On the other hand, if the rod has a jagged surface, I successively feel new sensations and am able to note the direction in which they are moving; I can form for myself, although with great difficulty, a single perception of the multiple sensations. Even if the rod had only one or two irregularities, these would distort my skin and thus indicate an agent moving continuously across my arm. In this case and in similar experiments, I would not deny that the length of the rod could be perceived, at least in a general way.

(88) To avoid any equivocation, the words `agent' and `recipient' must here be understood solely in relationship to the sensations. If I see a living body cut by a knife, the body, relative to myself who see, is as much an agent as the knife, but, relative to the living body that receives the impression of the knife, the knife is the agent and the body the recipient.

(89) OT, 842-844.

(90) I do not think, however, that it is possible to argue from the extension of the fundamental feeling to the extension of the body, which acts directly on the soul. For this reason, in The Origin of Thought, I demonstrated the extension of the body by deducing it solely from the action of external bodies on our body. Cf. OT, 842-871.

(91) Cf. OT, 806.

(92) Letter to Prof. Scarpa, 8th September 1801.

(93) We must note carefully the disharmony we are discussing between the subjective and extrasubjective body. When I say `the pain I feel in a finger' I am speaking about the subjective body. When I say `the impression made by a point pricking my finger and the movement it produces to the brain', I am speaking about the extrasubjective body. But what is this extrasubjective body and extension which we wish to translate, as it were, into a subjective body and extension? Note how I perceive the point, the impression and the movement of the whole nerve to the brain. I perceive them by touch and sight: by touch, by actually touching them or imagining they can be touched; by sight, by actually seeing them or imagining they can be seen. Now, if I touched or imagined I touched with parts of my body the point, wound and whole length of the nerve up to the brain, I would trace a line on the surface of my body which would have the same length as the nerve; a sensation would correspond to the whole line where the surface of my body was touched. If we say that the impression and movement of the extrasubjective body has the same length as the nerve from the finger to the brain, we are saying that the impression and movement is the cause of a subjective feeling of equal length. In order to express in precise philosophical language the relationship between the anatomical, extrasubjective body and the subjective body, we would have to say that the following law applies in our example: `If a living body is modified by touch, which produces in the person perceiving the modification a subjective, extended feeling whose length is the distance from the finger to the brain, a sensation having the extension of a physical point located in the finger is aroused in the subject of the modified body.' The same reasoning would also apply to sight.

(94) This is another fact concerning the relationship between corporeal sensitivity and the unlimited space given in the fundamental feeling (cf. 191-194). Note that the painful sensation cannot be referred by habit to the place of the amputated fingers. Cf. OT, 761, 762.

(95) Coldness of the skin is shown also by external signs, such as paleness, dryness, wrinkling, goose-flesh, loss of feeling, etc.

(96) The earlier thinkers had also observed the phenomenon of the feeling of cold diffused only on the surface. Celsus distinguishes between `cold' and 'fright': `I speak of "cold" when the extremities of the limbs are frozen; of "fright" when the whole body trembles' (Bk. 3, c. 3).

(97) The distinction between the subjective and the extrasubjective way of perceiving the body is further strengthened by reflecting on the phenomenon sometimes experienced by sick people, who complain of feeling cold, although their body-heat, according to the reading on a thermometer or even felt by hand, is normal, or even higher than normal. The same can be said about feeling hot. The difference of opinion arises because the sick perceive their body subjectively, but anyone touching them perceives it extrasubjectively.

(98) Among the studies carried out recently on the membranes present externally in the surface of the body, those of Donné are important. He observed that the skin secretes an acid fluid, while the mucous membranes inside the body from the mouth to the anus secrete an alkaline fluid. He thought the explanation could be electrical currents between both membranes acting like the two poles of Volta's battery. Donné presented these findings to the Academy of Science of Paris (cf. no. 38 of the Journal of the Institut, 1834). Matteucci, in an article in the Biblioth. Univ. (August, 1834), accepted these facts, but did not agree that the acid and alkaline substances, separated from each other by the body's internal and external surfaces, were the cause of electrical currents. He thought they were the effects of these currents, principally because the acidity and alkalinity remained after death, while the electrical currents ceased. They therefore seemed to be an effect of life. We see how all these studies must contribute to discovering the laws of the relationship between feeling and the ordinary, extrasubjective body, but the relationship can be one only of parallelism, never of cause and effect, as I shall explain.

(99) Prof. Santarelli's findings are presented in the Giornale Accadico, vol. 54, Jan., Feb. and March, 1832. However, the professor, despite such an important observation, does not show himself completely free of the misconception we are refuting. `Consciousness,' he had said a little earlier, 'makes us attribute sensation to the organ where it arises' (no. 36). The proposition is not exact. In the first place, sensation does not arise when the movement of the nerve begins. Granted all the movement necessary for arousing sensation, it arises immediately, locating itself appropriately, according to certain hidden laws which must be deduced, as I have said, by observation. In the second place, we refer the feeling to the surface even when the movement of the nerve does not begin at the surface, as in the case of cold skin produced by fever or fright.

(100) Ricerche fisiologiche intorno alla vita e alla morte, pt. 1, art. 6, §4. We would do well to investigate carefully whether the places where the pain manifests itself are not the extremities of some complex or organ.

(101) For this to be possible, we would have to suppose that the fluid issuing from the nerve canals finds other natural vessels suitable for constructing a continuation of the canals.

(102) These sensations give us two kinds of different phenomena: 1. those which I call the phenomenal part, and 2. those which the sensations have in common with touch. This arises from the two laws of shaped and non-shaped sensitivity. As we have seen, the principle of the law of shaped sensitivity is that `surfaces affected by a stimulus give shaped sensations'.

(103) Relative to this, changes due to disease manifest extraordinary phenomena that should be carefully assembled and studied. Phenomena like this would throw much light on the theory of sensitivity. We have an example in a man subject to convulsions. When he was in a convulsion, he did not hear sounds directed to his ear, but did hear when the sound waves struck his epigastrium and the vicinity of the apex of his heart. Cf. Bulletino di scienze mediche, published in Bologna, Year 4, vol. 6, facc. 131 ss., September and October, 1832.

(104) I do not mean natural stimuli, which are conditions rather than accidental increase of the vitality of the organs. Such stimuli belong to natural vitality, which is the third kind of causes I have listed. This vitality, however, also has its own levels, which are largely dependent on natural stimuli. Thus the blood is the natural stimulant of the brain, and the quantity of vital excitement of this main organ depends on the amount of such a stimulus. The stimuli I am speaking about, therefore, are accidental and foreign, like food and alcoholic beverages, etc. For example, the experiments carried out by Davy at the Royal Institute of Bristol with nitric acid and nitrogen gas, demonstrate that a person breathing the gas manifests phenomena similar to those of the early stage of drunkenness: objects become very clear, hearing acquires an extraordinary sensitivity, muscular strength increases, with an accompanying tendency to move about, laugh, etc.

(105) St. Augustine himself was desperate to find a solution to the problem. He writes: `The way in which spirits adhere to bodies and become animals is extraordinary. We humans cannot understand it, and we ourselves are composed in the same way' (De Civ. Dei, 21, 10). It must be carefully noted here that we do not claim to have explained the interaction between soul and body, but only to have demonstrated that philosophers ask the question out of context. This makes any solution not only difficult but impossible and absurd. On the other hand, once the real nature of the problem is known, the matter is reduced to the action of two beings. This mutual action is explained in exactly the same way as all the other facts of the universe consisting in mutual actions.

(106) The facts adduced by phrenologists must be separated from the arguments and systems they use. Unfortunately their systems are very often affected by materialism, because they give so much importance to the study of matter and very little to the study of spirit. Logic was not their chosen discipline, and consequently they have not hesitated to disseminate absurd conclusions in every direction. Examples of their false reasoning, which is not worth the trouble of correcting, can be seen even in the most recent writers, for example, Broussais and others. But we accept facts gratefully whatever their source. If they have been verified, they are common property, bringing greater light, and confirming the truth, the sole object of our work and love.