Return to Contents

Chapter 8

The Laws Governing The Relationship Between
The Feeling Principle And The Sensiferous Principle

135. We shall now investigate in greater depth the nature of the feeling principle, soul, and its relationship with the sensiferous principle, body. But before doing so, we must dismiss any popular ideas we may have formed about body and soul, and mistrust the different ways people speak about material and spiritual substances. Our task is to investigate how the ideas of body and soul originate and take form in our minds, how reliable these ideas are, and whether imagination adds anything to them. Imagination easily invents, or adds so much to our thoughts that they lose their pristine simplicity. As I have said, we must, by divesting our thoughts of the phantasy that clothes them, keep them in their naked simplicity.

136. Only observation and analysis can perform this task. We have to observe and analyse carefully the feelings we are aware of and see what ideas of the soul and body we can draw from them. If our opinions and persuasions about the body and soul do not have for their foundation and origin the feelings we experience, we must regard these thoughts as inventions of the imagination, and exclude them entirely from knowledge, like all false ideas.

137. The feelings we are speaking about must be put in order through observation, that is, we must distinguish our first, independent feelings from those which we observe to be dependent. Only after such a carefully ordered observation, can we safely commence the analysis.

138. Our first, immediately observable feeling is our fundamental feeling, as we have called it. Its existence has been shown and described in The Origin of Thought, to which we refer the reader.(71) We said that human beings have an intellective-fundamental feeling, different from the corporeal-fundamental feeling, although the subject of both is a single human being. Here we are not concerned with the intellective but solely with the animal part, common to both humans and animals.

139. In order to form a clear idea of the corporeal-fundamental feeling we have to strip it of every other feeling or sensation. We have to close our eyes and remove, first of all, every sensation of light, then all the sensations of our external senses, and finally all the partial feelings aroused in our body by individual stimuli. When all these external and partial feelings have been completely removed, the animal, in my opinion, still subsists with the feeling I have called corporeal-fundamental feeling, or feeling of life. We then come to know that this feeling is entirely uniform and simple: it has no shape because shape is given us by the exterior senses; it is not coloured because colour is supplied solely by our eyes. Having neither shape nor colour, it cannot have any surrounding limits that situate it in space.

140. We can in fact reflect on this first feeling, but without the experience of other sensations we could never extract from it our present ideas and concepts of the body. However, it would offer us sufficient ground to understand that two active principles are united in us, namely, that we feel, and that this feeling comes to us from the action of something different from ourselves, which, however, can be defined only as the proximate cause of our vital feeling.

141. If we wanted to give a name to the activity taking place directly within us and chose the word body, we could be sure that no one would understand us. The reason is very clear: the only meaning we can give the word is `proximate cause of the unique feeling we experience', a feeling which is, as it were, dumb, deaf, blind and empty. Everyone else, however, would be using the word to indicate the cause of their innumerable vivid, changing, moving, individual, extended, coloured sensations. For others, the word would indicate not only the cause of the sensations but also the subject of many of them, because they would take the sensations to be sensible qualities of the cause.

142. We can now ask who uses the word `body' more correctly: those in our hypothesis who are blind and deaf, bereft of every particular sensation, but able to reflect, or the many others who, enriched by the innumerable, attractive sensations of their particular organs, begin to philosophise?(72)

143. The question is not as strange as it first appears. There is no doubt that those who have only the fundamental feeling as the source of their ideas will know only that `body' is an active principle generating the simple feeling. Others will be able to draw upon many different feelings furnishing them with a great deal of knowledge about the principle which causes those feelings. But their possession of such abundant material does not ensure that they can legitimately deduce any wealth of knowledge from it. It is far easier to arrive by reflection at a single, simple conclusion than to work through many sources of information.

People equipped with many different sensations can no doubt form innumerable opinions and convictions about bodies, and think, write and talk about them at length. But those we have in mind, whose total knowledge is limited to a single, stated proposition to which nothing can be added, may well have greater understanding of body than those whose quantity of knowledge is far more extensive. In a word, our simple-minded persons could provide the word `body' with ideas more accurate and precise than those furnished by the learned.

144. Before we can logically accept that popular ideas about the nature and properties of the body, formed from acquired sensations, are genuine and free of all error, we have to presume: 1. that external, acquired sensations indicate the nature of the body more accurately than the fundamental feeling; 2. that in deducing knowledge about bodies from acquired sensations, only the faculty of reason is used, not persuasion. Persuasion, aided by imagination, continually fabricates opinions that are completely arbitrary.

145. Unfortunately for the mass of people, these two suppositions cannot be easily proved. We cannot easily show: 1. that corporeal nature is more acurately indicated by what we feel and experience in acquired sensations than by our experience of the fundamental feeling; 2. that when people in general suddenly begin to reflect, they refrain from using their imagination to fabricate notions of bodies from external, partial sensations, and use reason instead of their capacity for blindly believing in arbitrarily formed opinions. The difficulty of demonstrating these two points is immense, and indeed a more balanced reflection demonstrates precisely the contrary of the two suppositions.

146. Serious reflection on the second supposition reveals that in general people prefer not to suspend their judgment; if they cannot bring their judgments to a strict logical conclusion, they rush to any conclusion, using the faculty we call persuasion. This faculty consists in forming an opinion to which full credence is given, although the opinion lacks logical foundations. Popular philosophical ideas about nature and the properties of bodies have been formed this way.(73)

147. The inaccuracy of the first supposition is also easily demonstrated. We need only note that acquired sensations are subsequent to the fundamental feeling; they are in fact simply a partial modification of the feeling. Hence, it is clear that when we know our body through feelings (which are effects of the body's action), the first action carried out on our soul by this principle called `body' is the most constant, universal action, which alone can make us know the nature of the body. Partial variations of this universal, constant action of the body help us greatly in knowing the laws which govern that first action wherein all other actions are virtually contained. But the variations alone, without their first original action, make us know the body only partially, and certainly not without error.(74)

148. Even granted the corporeal fundamental feeling, it will be said that we cannot observe extension in it, and therefore cannot say it makes us know our body, of which extension is an essential property. The objection, however, clearly concerns extension based on the concept obtained from external sensations. Our task is to ascertain whether there is another concept of extension in addition to that obtained from external sensations, or whether, more accurately, extension is already felt in the fundamental feeling, although without the qualities provided by external sensations. We must also decide if these qualities are genuine or simply illusions supplied by the impatient human spirit. This is often the case with the ideas of corporeal qualities formed by people generally.

149. I am convinced that the same extension is felt in the fundamental feeling as in the external sensations, but without the phenomenal qualities (which are not entirely true and valid), although the external sensations lead us to believe that extension possesses these qualities. Extension felt in this way I call fundamental or internal extension. I admit that it is difficult to form an accurate concept of it, because people generally cannot conceive any real extension except by means of shape, colours, and limits. But if serious thinkers turn their attention to the extension obtained from all our feelings and then set aside everything supplied by external sense, they will be able to form the concept of the extension I am speaking of. All the qualities supplied by external sense can be reduced to limits, colours, and the possibility of motion, that is, the possibility of variations in the colours. When we remove these qualities, we do not eliminate extension. The foundation and subject, as it were, of the limits and colours remains (even if it seems undefinable) [App., no. 4].

150. We must, therefore, be very cautious about accepting all the notions popularly formed about corporeal nature. Thinkers and those who seek the truth must subject such notions to the most exacting critique and separate out everything that does not strictly belong to extension. Otherwise our ideas will be formed from a figment of our imagination, as so often happens. In order to subject all popular ideas of the body and its qualities to rigorous investigation, we need to see whether they have been formed directly or as the arbitary product of our imagination.

151. We must return to our hypothetical subjects who although unable to use their external senses, can think and reason about their internal fundamental feeling.

These sentient subjects could now be affected by two kinds of successive sensations: 1. extremely intense feelings of pleasure and pain where the feelings present no shape, limits or colour; 2. sensations or feelings, such as touch and sight, which present shape, limits and colours. In our example, the subjects have only (corporeal) sensations of the first kind, without shape, boundaries and colours. A question immediately comes to mind: `Are these shapeless and colourless sensations which we receive, referred to some part of our body?' The question itself is sufficient indication that we have not entirely rid ourselves of popular, common opinions about the body, and are as yet incapable of conceiving the state of a human being who has only the corporeal fundamental feeling and sensations devoid of shape and colour. To ask if such a being would refer sensations of pleasure and pain to some part of his body presupposes that for him his body already has distinct parts. But his body, relative to himself, cannot have distinct parts, because the parts cannot be perceived without his perceiving the limits distinguishing them and making them parts of the whole. Such a being, however, has never perceived nor felt the limits in any way, nor the shapes formed by the limits.

152. If the pleasant or painful sensations are corporeal, as we have supposed, they can be caused only by changes taking place in our subjects' bodies, that is, by movements of their nerves stimulated in some way.

But this kind of language, too, shows that popular ideas of bodies are still present as an obstacle to understanding the argument, which cannot be grasped until such ideas are completely banished. By insisting that pleasant or painful sensations can be caused by nerve changes, and so on, we have presupposed knowledge of nerves in our body, and of their power when stimulated to generate sensations by their movement. Moreover, we have accepted these things as though they had been proved with certainty, despite setting out with the deliberate intention of testing them and not admitting them as valid in our argument until they had been proved true. We wanted to avoid introducing unproven current opinion into our work lest we construct a system based on deceptive and erroneous preconceptions.

If we say that the shapeless, colourless sensations (hypothetically granted to the feeling subject) are the effects of movement stimulated in certain feeling parts of our body, we have begun to describe the body according to ideas provided by the external senses, especially the eyes and hands. Anatomy is founded on sensations of this kind, and our argument now begins by presupposing, as legitimate and certain, tenets of popular philosophy about the body for which we no longer require proof. We presuppose that the phenomena given by our eyes and hands constitute the objective reality and truth of things. We also presuppose that the only ideas we have of the body are those I call visual and tactile. In a word, when we say body we mean the visible, tactile body. This would be true if the only way of knowing the body were by means of the eyes and hands. But there is, as we have shown, another more basic way which precedes all others, even if it presents no shapes or colours. Our question, based on serious reflection and without preconceptions, has to be posed as follows: `Do those who have only the fundamental feeling refer the shapeless and colourless sensations they receive to some part of their visible, tactile body?'

It must be carefully noted that here we are not asking simply about the body of these hypothetical subjects, but about their visible, tactile body, the phenomenal body which manifests itself to us by the sensations of sight and touch. This phenomenal body, however, does not exist for those who are supposed to be without the sensations of sight and touch. To ask if they refer the pain or pleasure they feel to some part of their tactile or visible body or of their body shaped in a more general way, is to ask about something foreign to their state. On the other hand, refusing to allow the question simply leaves undecided whether the phenomenal body of sight and touch (the object of anatomy) is real or illusory.

153. We can therefore never refer any pleasure that we experience to any part of our shaped body, if such pleasure does not present shaped space to our feeling principle and we have not yet felt and perceived our body as a shaped object with parts. Such a body does not yet exist for us. On the other hand, extension is certainly present in corporeal sensations, which are only simple modifications of the fundamental feeling. This extension, which I have called internal (cf. 149) is completely shapeless and devoid of parts, like the extension itself of the fundamental feeling.

154. We must now consider carefully how the sentient subject begins to feel any shaped extension.

First of all, we should note that corporeal extension is shaped only by the limits surrounding it on all sides. Consequently, the perception of any shape implies the perception of the limits enclosing a space.

155. Indeed, very careful observation reveals the great difference between feeling and perceiving a limited space, and feeling and perceiving the limits enclosing the space. If this distinction is not borne in mind, what I wish to say cannot be understood.

I have said we cannot feel or perceive shape without feeling the limits that form it. This is what happens when touch and sight perceive shape: our hand and eyes perceive only the limits of the objects, that is, their surfaces. Conversely, while the extension in which the fundamental feeling terminates, along with the other internal feelings that modify the fundamental feeling without presenting shape, is undoubtedly limited, its limits are not felt. Thus, although the felt extension is limited, it lacks shape, having no felt limits.

156. What we have just said is important and requires further comment.

In order to feel the limits of my own body, I have to feel something beyond my body, something terminating my body, for the clear reason that no thing is its own limit.

157. If I consider the outline of my body, the limit is a line that follows the body's different curves and angles. But I cannot mentally conceive a line without conceiving simultaneously a space on either side of the line, for example, a convex space on one side and a concave space on the other. Without this condition, the line cannot be conceived at all. Thus, if the line is my body, the space on the other side of the line will be either empty or full but always different from my body. I cannot feel and perceive the line terminating my body unless I simultaneously perceive something beyond and outside my body.

158. Now the the same is true if, instead of considering the line-limit of my body, I consider the limit extended as a surface. I can conceive a surface only if I perceive it as a plane cutting a solid space in half, that is, I need to perceive the two parts of the solid divided by, and lying on either side of, the surface. I cannot perceive the surface of my body unless I perceive it as a division between the space occupied by my body and the space outside my body. I have to conclude therefore that I could never feel and perceive the surface limits of my body unless I felt and perceived the external space limiting it.

159. The preceding observation demonstrates clearly why there can be no shape in the fundamental feeling, although the feeling is limited in itself.

The fundamental feeling, like the body felt by it, is limited, but presents no shape; it seems as formless and indeterminate as black night. It feels only the body, nothing more; and because it feels no other space outside the body, it does not feel the limits of the body that give it shape. The same is true of all feelings which have no shape: they feel no space outside the body which constitutes their limits.

160. An important corollary of the preceding observation gives us a firm principle for determining the feelings in which, while feeling corporeal extension, we feel no shape: `Whenever a feeling is diffused in a given extension of our body but tells us nothing more about the extension or about anything limiting the extension, the feeling has no shape in space.' Thus, pain in a sensitive part of our body produces a shapeless sensation, if the pain is due to an internal alteration or movement of the parts and not to an external stimulus. The same is true if the stimulus gives no surface sensation limiting the solid space in which the pain is diffused.(75)

161. We see therefore that the space felt in the fundamental feeling, and all undefined space, is solid, having the three distinct dimensions of length, height and breadth. Contrariwise, the space perceived by shaped feelings is surface space, because the sensations of external touch and of sight present only a surface-extended feeling terminated by lines.

162. We must not think that external touch also perceives solid spaces, even if we form some concept of solids by means of touch and sight, and by means of the imagination.

163. We grant, of course, that solids, considered as the subject of geometry and anatomy, are mentally conceived by the help of touch and sight, and also of the imagination. But it is no less true that the perceptions proper to these two senses never go beyond a surface, and that we know only the surfaces of solids perceived in this way.

164. No one can deny that the concept of something solid is determined by surfaces, but it is difficult to explain how these felt surfaces present a solid. Clearly surfaces can circumscribe a solid only if they have a given situation in space, with such a relationship between them that they enclose and limit a portion of solid space in every direction. In order, therefore, to perceive solids through touch and sight, that is, by means of surfaces, which are the immediate, proper term of these senses, it is not sufficient that the surfaces be perceived; their relative situation must also be perceived. For this to happen, we need somehow to feel the same solid space in which the surfaces extend, especially in the case of a line or felt surface which supposes that we feel what is on either side of the surface (cf. 156-158). This first difficulty is eased by the theory of the fundamental feeling: solid space, whose limits must be the surfaces felt by touch and sight, is precisely where, as we have said, the fundamental feeling is extended (cf. 161). This fact itself is a proof of the existence of the fundamental feeling, for without this feeling we could not explain how touch and sight enable us to conceive solids.

165. But because of its many variations and the laws governing it, the fact still needs further explanation. For example, if the solid space which is the term of our fundamental feeling is no more than the space occupied by our material body, how can we feel the respective position of the surfaces of exterior bodies? The solid space of these bodies is foreign to us and therefore cannot be a term of our fundamental feeling. It may be suggested that if we know the position in space of the surfaces of our own body, we must also conceive the space beyond these surfaces because, as we have already explained, a surface cannot be felt if we have no feeling at all of what is outside it (cf. 156-158). This solution, however, only increases the difficulty. The supposition that the fundamental space is only that of our body may indeed allow us to think we have explained how we perceive at least the surfaces of our own body, but if the solid space of the fundamental feeling is no more than that of our body, the very perception of the position of the surfaces of our body obviously becomes impossible. It is clear, therefore, that in order to be capable of knowing the position in space of the surfaces of our body, we have to admit that simple unlimited space, as well as the space of our body, is the term of our fundamental feeling, and that this is true even though our sense-organs occupy a limited space, and material sensations arise in, and are limited to the organs.

166. There is still greater need to presuppose this if we are to explain how touch can inform us of the solidity of external bodies, when their surfaces are perceived solely by means of touch. I fully agree that when we hold a ball in our hand, we are aware of a solid sphere. We experience a concave sensation in the internal surface of our hand to which must correspond a similar, convex surface in the body. But the problem is how to identify the space that our spirit had to perceive so that it could have this awareness. If touch indicates the concave surface of our hand, it must also indicate the convex surface of the ball. But both surfaces are only limits of solid space. Our spirit therefore cannot be aware of the concave form assumed by the palm of our hand or of the convex form of the ball unless we suppose the spirit to have in some way the feeling of the solid space limited by these surfaces. Furthermore our spirit feels both the solid space occupied by our hand and the solid space occupied by the ball. But with one difference: together with the feeling of the solid space occupied by our hand, our spirit also has the feeling of the felt, living matter of our hand. The latter feeling is not present in the portion of solid space occupied by the ball. This presents us with a very important corollary: `No part of space can be perceived unless we presuppose the feeling of all space,' or: `We cannot feel limited space unless we feel unlimited space.'

167. What makes it difficult for us to be convinced of this is the immense difference between the surface sensation of touch and the fundamental feeling of space. The former is vivid, actual, transitory; the latter is habitual, immanent, uniform and simply does not stimulate or attract our reflection. Thus the illusion easily arises that the only feelings that exist are those of actual, partial sensations, whereas these merely indicate the limits bounding the universal feeling.

168. However, other arguments demonstrate the necessity of presupposing in the human soul both a basic feeling of unlimited space and a material feeling of one's own feelable body which occupies only a little part of that space. If we consider, for example, the phenomenon of movement, especially active movement by which the animal transports its body from one place to another, we find that such a phenomenon is impossible unless we presuppose that human beings, in addition to feeling the space occupied by their own body, also feel space not occupied by their body. If we did not feel the latter, we would be unable to transport our body from the place it occupies to a space it does not occupy.

169. The laws governing the phenomena of sight offer us an even more effective proof of the argument. Let us suppose that the sensation of sight considered in itself presents phenomenally a simple surface plane that can never be used to form a solid. Let us also suppose that the solids perceived by sight are formed by means of an unknown, habitual judgment or association of sensations. In this supposition, the luminous points of the optic sensation would be referred to the corresponding points of the sensation of touch and movement in such a way that the sensation of sight would act as a sign to the soul for noting the solid forms and distances perceived by touch and movement.(76) If this were all that was involved, the difficulty would concern touch alone, and once we had explained how touch perceives solids, we would have explained everything. We would need no other argument to demonstrate the fundamental feeling of unlimited space.

But my argument is drawn from the laws of perspective governing external objects, which I have already discussed (cf. 115-129). One of these laws, the basis of many others, states that when the optic axes meet at a fixed external point, the soul sees one point, although the sensations are two because we have two eyes. The law is determined by straight lines drawn in the space outside our body. The laws of optics therefore do not depend on the portion of space occupied by our body, but on external, unlimited space, as the whole science of optics demonstrates. This science establishes the laws of vision; it does not investigate what happens inside the eyes or the brain but simply indicates lines beginning from the eye and continuing to a luminous body, as if the eye itself projected the visual rays and struck the object seen at a distance (as the ancient thinkers believed).(77)

This error of the ancient thinkers was natural and fully excusable, because in effect the phenomena of sight respond perfectly to the hypothesis that the act of vision is a projection of visual rays to the object. But the fact is that rays emanating from the eyes do not exist. We cannot doubt that the eyes receive impressions like all the other external sense-organs, that the impressions are two, because the eyes are two, and that the impressions do not physically unite.

How, therefore, can the sensations of the eyes be subject to the laws of external space if this space itself is not part of our fundamental feeling? When both our eyes are fixed on a distant point, the point is outside and distant from our eyes. The very energy required for focusing both eyes on the point demonstrates that we see one point only with both eyes, although the eyes are two and receive two sensations. Thus the space where we locate the fixed point is a plane in unlimited space. This plane and its position, however, must be given by nature, as we have said (cf. 115-116); sensation alone as experienced by our eyes cannot give it, because this kind of sensation, in its physical reality, is double, and adheres to the retina. If, for example, we fix our eyes on a relatively close object, we notice that we have to turn the two planes of the retinas so that the apex of the angle formed by the verticals striking the retinas is the fixed object. This explanation of how both retinas can thus see the same object would obviously be impossible if external space were not considered as part of the fundamental feeling which enables the action of the retinas to be determined by the laws of this external space. Consequently, space, relative to the actual, partial and transitory sensation of sight, is said to be external, but relative to the fundamental feeling, is truly internal.

170. When we gaze steadily at some distant object, we are conscious of directing our sense-activity to a point outside us, and outside our material feeling (which would be impossible if the point were not within the sphere of our activity or fundamental feeling). We can also act on the external point by using other faculties: for example, we could throw a stone and, if our human nature were perfect, hit the target infallibly. We are told that sight sensation gives only a sign of the object and that the sign is used as a norm for the locomotive force needed to determine the direction and energy of the throw. Although this is possible, it does not explain the phenomenon sufficiently, for the following reasons.

1st. If the sign is different from the object, we see the sign but not, properly speaking, the object. If, however, we saw both the object and the sign, we would see - contrary to fact - two things, the sign in us and the object outside us; and the original difficulty returns. If we see only the sign, it must be situated somewhere, otherwise we could not direct our aim. We see it, therefore, either in our body or outside our body. It cannot be in our body, first, because we never say we see external objects in our body, and second, because the sign could not indicate the external spot to aim at; rather it would indicate our body as our target. If the sign of the object appears outside our body, as the laws of optics show, we still have the original difficulty. Seeing the sign in external space without seeing the object contributes nothing to solving the problem.

2nd. To introduce an habitual judgment by which we refer the sight sensation to the external object supplied by touch and movement does not, on careful examination, explain the matter satisfactorily. First, it is difficult to understand how touch sensation, which is not present and must be supplied by the imagination, can prevail over sight which is present. This requires an extraordinary illusion by which touch changes the place of the object, making it appear where it is not. Second, we would have to compare the actual sight sensation with the imaginary sensation of touch and the feeling of movement associated with touch. In this comparison, we could not be unaware that the imaginary sensation prevails over and subjects the sight sensation to its own laws, granted the laws of vision.

Third, touch alone knows the distance of objects, which are not felt unless they touch the body. Consequently, we have only the feeling and intensity of actual movement for measuring the distance of an object from us by means of the time required to reach the object. But the movement by which we transport our body from one place to another in unlimited space cannot be explained without the feeling of unlimited space (cf. 168).

Fourth, the feeling of the active movement of our body is unable to give us the precise measure of the distance of a body we see; we also need the help of the visual sensation in which objects grow smaller in proportion to the distance. This gradation of the distance of different bodies indicated by their sizes helps us to know the relative distance of many bodies but does not help us to know the absolute distance of a body close at hand. If we want to throw the stone accurately, we need to know the absolute, not the comparative, distance.

Fifth, if our feeling of the active movement necessary for reaching a body is not in fact seconded by sight (which helps us to know only comparative distances of objects), it cannot in any way give us the measure of the absolute distance of the object, unless we in fact move towards it and touch it. Sight, therefore, which actually guides the thrower's arm, needs some other means to know distances independently of actual movement.

3rd. Finally, I agree that the association of sight with touch and with the feeling of movement produces in us an habitual criterion which helps us to measure the absolute distance of objects. But this association would be inexplicable and impossible, if the object were not actually seen in a point of unlimited space. If the eye saw only one object, not many, without any association of touch and movement, it would not know the distance of the object, because it would have no other felt object with which to make the comparison. Equally, if it did see the two objects whose distance is to be measured, but did not feel them in two points of unlimited space, no comparison could be made at all. This is true whether the objects are felt by sight alone or by different senses such as sight and touch joined with the feeling of movement.

These reasons demonstrate rigorously that the phenomena of the perception of surfaces are inexplicable unless we first grant solid, uniform, unlimited space in the feeling of the soul.

171. We can see how mistaken Emmanuel Kant was when he said that space was the form of the external sense (if we understand form as he understood it). I admit that in introducing his `form', he saw better than others the difficulty of explaining the phenomena of external sensitivity, and I can accept his indirect confession of the need to find some principle, then unknown to philosophers, which would explain the phenomena. I must, however, indicate two serious errors in his theory.

1st. His arbitrary form is insufficient. This `form' is only a law or natural disposition which obliges the spirit to clothe its external sensations with space. If this were to take place, sensations would have to come first in order to be clothed with space, and be followed by the space needed to clothe them. But the opposite is true: no external sensation exists unless it is in space. Moreover, the spirit would create space on the occasion of sensations. But because we have no proof of this, such an affirmation is arbitrary. In fact, consciousness tells us the contrary: our soul does not create space; space is given to and imposed on the soul.

2nd. If space were a creation of the soul, it would be only a modification of the soul, not something in itself. Consequently even bodies would be subjective illusions, since they need space to exist.

172. These difficulties can be entirely avoided if we posit pure, unlimited space as the term of the fundamental feeling. The first difficulty disappears because in this case sensations truly exist in space. The second loses all validity if our own theory is correctly understood. The term of our feeling does not change its nature whether it is given to us on the occasion of an accidental, transitory sensation, or at the beginning of our existence by the Creator himself. In both cases it retains its nature as term of our feeling. And if it has the nature of term, it is really distinct from the feeling principle which is the subject. Hence, it is not a modification of the subject. It is something extrasubjective, not subjective, and when applied to the thinking human being is non-self, which cannot in any way be confused with its opposite, self.

173. What we said at the beginning, therefore, remains true: solid space, which comes to be circumscribed by the surface sensations of sight(78) and touch, is given by nature and not by these sense-organs, which only limit space, enveloping it in surfaces, and therefore presuppose it as already given to the spirit.

Touch, for example, makes us feel the whole surface of a sphere or the six surfaces terminating a cube. But it never enters a cube or sphere; only our imagination does this, creating an `inside'. The imagination is supported and strengthened by the mutability of the shape of the two solids; the sphere can be divided into two hemispheres, the cube can be cut in any direction. This gives rise to the illusion that we touch and see the inside of the sphere and cube, when in fact we see only fresh surfaces as a result of cutting the two bodies in half and changing their shape and location. Even if both bodies were smashed into smithereens, we would still neither see nor touch the inside, because every tiny bit of them would itself be a new body, offering only surfaces to our touch and eye. Our touch and sight would never penetrate what is solid because what is solid is not the term of these senses; they always see and touch surfaces, which can be infinitely changed. This mutability, aided by the imagination, leads us to believe, as I have said, that solids themselves are felt with our hands and seen with our eyes.

174. Solidity, therefore, is given by nature but without limits. Only that part is limited in which what is felt corporeally is extended.

175. We can now see how a serious error arose in sensist philosophy, whose only idea of substance is that formed from bodies. This idea of bodies, however, is only the common, popular idea formed from external, shaped sensations. The sensists observed that shaped sensations presented only sensations of surfaces to the soul, and nothing solid beyond the surfaces. They concluded that corporeal substance, which is thought to support the surface, is entirely unknown, and consequently that all substances are unknown.(79)

176. But such a conclusion is hasty and false. We must distinguish different substances and not reduce the concept of substance in general to the concept of the particular substance of bodies. Moreover there is a first, fundamental way of feeling and perceiving space and solid bodies. I fully agree that the senses of touch and sight cannot in any way give us the idea of corporeal substance, which presupposes something solid and not mere surfaces. But if we reduce the concept of body to the aggregate of the qualities given us by these surface senses, we will never be able to form a positive concept of body as substance, nor even of surfaces enclosing a space. The concepts of solid space, corporeal substance and substance in general are not deduced from touch and sight.

177. Not only sensists but philosophers in general have, it seems, given no more than passing attention to what I call `surface sensations', which deserve the closest consideration. Indeed they offer a new and clear proof of the simplicity of the feeling principle.

What is extended in surfaces and devoid of thickness of any kind cannot be a body, because extension in the three dimensions of length, breadth and depth is essential to body. It is only the mind that by abstraction separates the dimensions; in reality they are inseparable and indivisible. If those who feel were to feel the three dimensions, they could never have sensations in the form of pure surfaces because the felt surface would have to be really separated from the dimension of depth, a separation which contradicts our concept of bodies. Surface sensations, therefore, are essentially incorporeal; they are phenomena that take place only in an entirely incorporeal, simple principle.

No one can doubt that touch and sight sensations are limited to surfaces and do not penetrate the bodies we see and touch, even those with the most delicate of surfaces (cf. 173). But we can be misled into believing the opposite either by the transparency of the body, when we seem to see the colour below the surface, or by touching a soft body, when we seem to feel a harder body below. But even these sensations are only surface sensations, although they lead us to make a judgment about the bodies below the surfaces. We reason to these bodies from the quality of their combined effect. The effect itself, however, is never more than a surface sensation.

178. It may be suggested that these sensations are of only apparent surfaces, and that the soul, although it feels in the brain, refers its feeling to the extremities where its body is touched. But we have shown that it is gratuitous and contrary to fact to say that the soul feels in the brain.(80) This is a common mistake of physiologists, who confuse impression with sensation. They see that there is no sensation unless the disturbance of the nerve reaches the brain, and conclude that the brain feels. But nothing could be more gratuitous, because the only thing we can infer from this fact is that the propagation of the movement to the brain is a necessary condition of sensation. Such a fact, however, is not sufficient to determine the place where the sensation must be felt, a place that can be known only from its own factual existence.

179. Moreover, saying that the soul refers its feeling to the extremity where it is touched unnecessarily introduces a mysterious action. To say refer is both obscure and contradictory because the soul cannot refer a sensation that it does not have. But if it already has the sensation, the sensation must either be referred somewhere, in which case we have two sensations, or the soul must send the sensation somewhere, in which case we would be aware of its passage because as a sensation it must make itself felt at every point of its movement. Such an action, therefore, is neither real nor tenable as an explanation of how the soul or brain transmits and refers sensation to different parts of the body.

We have to say that the feeling of the soul is a simple fact, which either does or does not exist. If it exists, we must analyse it. If we find space in it, we must accept space as one of the feeling's properties and modes. We must not arbitrarily presuppose that the space we notice in sensation, whatever it is, is something different from sensation, or requires another action of the soul to explain it. Such a procedure would truly be a false use of hypothesis. If there are sensations which make the soul feel surfaces, these surfaces must be part of the sensations themselves. We do not need to suppose that the soul produces them there by referring the sensations to certain parts of the body.

180. These errors and the apparent clarity with which they are expressed deceive many superficial thinkers. The errors originate, as we have said, when we accept as proven some opinions about bodies which, lacking proof, are the product of our imagination. Indeed, the very statement `the soul refers sensations to certain parts of its body' implies that such a soul has a body endowed with shape and parts. But the contrary is true: the soul does not have a body endowed with shape and parts. It feels the body in this way only after receiving the surface sensations we are discussing.

Sensations of touch and sight cannot be referred by the soul to the phenomenal, anatomical body, which does not yet exist for it. The anatomical body begins to exist for the soul by means of touch, sight and shaped sensations in general. These sensations have within themselves a space extended in surfaces, and these surfaces are the origin of every form and shape, and of the many variations in form and shape caused by the continual change in surfaces. Thus the anatomist, when he has observed all the external surfaces of the human body, can go on to cut away the outer skin and discover another surface. He can then cut this away and so on, penetrating further into the body, but never seeing or touching anything other than another surface. The only knowledge he can obtain about this kind of body, no matter how perfect his instrument, is simply an aggregate of infinitely varying surface sensations which constitute the indefinitely variable limits of the anatomical body.

The anatomical body, therefore, exists for the soul only as an aggregate of its surface sensations which wonderfully delineate the body for it. We cannot accept that this phenomenal, anatomical body surrounding the soul exists prior to shaped sensations, so that the soul can place sensations in different parts of it. On the contrary, the different parts are, for the soul, the parts themselves of sensations, and the extension of the anatomical body is identical with the extension of the sensations of the soul. The soul, therefore, does not create extension and location for its sensations. The sensations are, from the outset, in extension and naturally located there.(81)

Notes

(71) Cf. 693 ss. Physiologists have recognised the existence of this fundamental feeling, calling it in Greek koinaisdhsiV, universal feeling.

(72) I say `others who begin to philosophise' because if we did not reflect on our sensations at all, we could not say that external bodies are their subject. In fact we could say nothing even to ourselves about our sensations, and our actions would be governed by sensible appearances.

(73) All this has been demonstrated in OT, 692 ss. where the theory of bodies is discussed. One of the errors found in common opinions about bodies, and now acknowledged by all philosophical schools, is the confusion between sensations and the qualities of external bodies. However, many errors found amongst the masses can be excused if we bear in mind what I said in Certainty, 1302-1306, about popular errors.

(74) For the relationship between acquired sensations and the fundamental feeling, see OT, 705, 706, where I have shown that acquired sensations are only modifications of the permanent, universal feeling.

(75) When Condillac speaks about the odours he supposes to be in the nostrils of his statue, he sometimes says that `the soul might consider itself to be all the different odours it sensed' (p. 58); other times he says that the soul might think `it has the odours within itself'. The statements are clearly contradictory, because if the soul believes it has the odours within itself, it cannot believe it is the odours. Neither of the statements is true. When the soul first has an odour, it neither distinguishes itself from the odour, nor confuses itself with the odour. It has not yet discovered itself. Its activity is only in the odour; it is completely ohlivious of itself. Hence, it cannot judge the relationship of identity or difference that the odour has with it.

(76) OT, 906-921.

(77) Cf. St. Augustine, De Genesi ad Litt., 1, 31.

(78) We said that the position of the surface plane of visual sensations has been wisely determined by the author of nature (cf. 115). But we must also note that although all visible points are depicted in the surface plane, they are referred to this plane according to the laws of vision. These laws state that an object of our vision is always situated at the apex of the angle made by the optic axes. The distance of the apex corresponds to the distance of the object. But in the pure, isolated sensation of the eye, the seeing subject finds nothing that marks the distance of an object. Hence, the sensation always has the form of a surface plane, like a screen stretched out, as it were, before our eye, but a screen suspended nowhere because there is nowhere to hang it; for the eye, it is the whole of space. Moreover, the screen could be changed into another nearer to the eye without the visual sensation undergoing any alteration if the objects appeared on the nearer screen with the correct relationship of vision, as Wheatstone's experiments demonstrate. Consequently, relative to pure eye sensation, the distance of the screen is indifferent, precisely because the screen, relative to the sensation, has neither distance nor location. But the case is not the same relative to the unlimited space which is the term of the fundamental feeling. If the visual sensation is compared with this space, it corresponds equally to all the planes (provided they are parallel) into which the space can be divided. Thus, we can say that the sensation of a disc seen by the eye corresponds in solid space to a cylinder that stretches to infinity. Hence, if an object seen at a distance grows in size as it approaches the eye, the growth becomes a sign to the eye that the object is approaching. Afterwards, touch and movement can verify the existence of the solid space that adheres to the fundamental feeling.

(79) The truth of this observation can be verified by reading chapter 23, bk. 2, of John Locke's Human Understanding. We see clearly how 1. he draws the idea of substance in general from the particular substance of bodies; 2. considers bodies as an amalgam of tactile and visible qualities; and therefore, 3. infers that the substance of bodies, and even substance in general, always remains entirely unknown to us. The following extract will suffice for those without time to read the whole chapter: `So that if any one will examine himself concerning his notion of pure substance in general' (we note how he speaks here of substance in general, not simply of the substance of bodies), `he will find he has no other idea of it at all, but only a supposition of he knows not what support of such qualities, which are capable of producing simple ideas in us; which qualities are commonly called accidents. If any one should be asked, what is the subject wherein colour or weight inheres, he would have nothing to say, but the solid extended parts' (here Locke is speaking of the particular substance of a visible, tactile body, not of substance in general): `and if he were demanded what is it that that solidity and extension adhere in, he would not be in a much better case than the Indian beforementioned, who, saying that the world was supported by a great elephant, was asked what the elephant rested on; to which his answer was, a great tortoise. But being again pressed to know what gave support to the broad-backed tortoise, replied, something, he knew not what.'

(80) OT, 732-734.

(81) It seems that sensation gives space to the soul because sensation, by limiting space, makes the limited space more vivid and therefore observable. Furthermore, the parts of a total sensation have a position in the sensation like objects seen in a mirror. But the same total sensation presupposes unlimited space devoid of material feeling.