CHAPTER 11

The subjective and the extrasubjective content
in external sensations

878. After observing and describing extrasubjective perception of bodies by touch, we should follow with observations on the other four senses to see what perception reveals for each one. But before doing so, we must carefully distinguish the extrasubjective and subjective elements present in every sensation, so that nothing subjective remains in the extrasubjective element. When this has been done, the extrasubjective perception will stand out clearly and indicate for us the extrasubjective value of each sense.

879. I have demonstrated two things:

1. Sensation is in us, not in external agents (cf. 632 ss. and 672 ss. [652]). The idealists misused this fact. I grant them its truth, but they should not have neglected other facts while acknowledging it. Their error was the result of insufficient observation, not of defective observation.

2. Sensations are in us as the term of actions done by something other than ourselves (ibid.).

This was the other fact neglected by the idealists, although no less clear than the first. In every sensation we experience a passive modification or disturbance within us, of which we are directly conscious which expresses the term of an external action. By their nature, therefore, sensations, although in us, inform us of something outside ourselves. We must either deny the difference between activity and passivity, or accept that to be conscious of an experience in us is to be conscious of an action done in us, but not by us.

880. Consciousness tells us that: 1. we are modified; 2. this modification is an action done in us, not by us. It tells us these two things simultaneously, with a single voice, as it were. Reflection then analyses this united evidence of consciousness, recognising the two things and considering each one separately. Next, the understanding applies the concept of substance to our consciousness of the action done in us, not by us. In this way it isolates and makes its object the external things on which it then meditates and reasons.

881. The principle for accurately distinguishing the subjective and extrasubjective elements in sensations is: 'Everything contained in sensations considered in themselves (and not according to the way they are produced) is subjective; everything contained in the concept of our passivity, a passivity attested by consciousness, is extrasubjective.'

882. Applying the principle, we discover the following extrasubjective parts in sensations:

1. Consciousness tells us we are passive in sensations, that is, we perceive a force in act. Our understanding then sees in this action an ens different from itself, that is, a body. Force then is the first part of the extrasubjective perception of bodies.

2. Consciousness attests that the disturbances and forces we feel are multiple. Multiplicity of bodies therefore is the second part of our extrasubjective perception of bodies.

3. Consciousness again, and reason, tell us that a force is actively present in every point of an extension without exception. We are thus led to the conviction that there is a continuous extension. This is the third part of the extrasubjective perception of bodies.

883. Analysis of these first three extrasubjective properties of bodies shows many others. I only make the following observation:
The force which is a property of bodies, is not any force capable of acting on our spirit. It acts in a particular way, determined by the subjective effects it produces in us, that is, by the subjective part of sensations such as pleasure, pain, heat, light, colours, etc. Now, corresponding to all the different kinds of sensations and effects of this force, there must be, in bodies, aptitudes or potencies for producing them. These potencies proceed from the force which is the essence of body, and is the body itself. The first quality of bodies, therefore, generates many other qualities, that is, causes all those aptitudes in which it expresses itself in its different effects (determinations of the force).(185)

884. Multiplicity is not a real property of corporeal nature except in so far as it is possible to imagine it in the continuous extension with which bodies are endowed. In fact, real multiplicity is accidental, a relationship of many mentally conceived bodies.

885. Finally, extension, especially when united to force, is the source of a great amount of information about corporeal properties. Because extension includes mobility, shape, divisibility, impenetrability, etc., all these properties are both real and extrasubjective, that is, in bodies themselves, not simply in us.(186)

886. The famous distinction between primary and secondary properties of bodies has its foundation in nature.
But it would be better to call the former extrasubjective and the latter subjective, although primary and secondary are not out of place because we form the idea of body with the extrasubjective properties and apply the subjective properties as accidents of bodies.

887. All that forms a sensation considered in itself is subjective (cf. 881).
Hence if we remove from sensations multiplicity, extension, and the force producing them and making them subsist (and anything else discovered through analysis of these three parts), anything left that we can observe is subjective.
We may note that feeling in the human being has a unity, that is, the unity of the sentient principle that gathers and unites its various modifications. Moreover, it is reasonable to believe that the nature of this sentient principle, and of the animal fundamental feeling, generates the different feelings, establishing and determining the characteristics of each. Nevertheless, we do not know sufficiently the nature of the principle and the feeling to understand this connection. The many, various changes undergone by feeling seem to us arbitrary and independent of each other; we cannot deduce them a priori.

888. I do not know whether this is due to my ignorance or whether, in this case, something lies hidden and mysterious to the human race. I have to be satisfied with indicating the many, varied kinds of sensations as basic facts without explaining them. I do not need to explain the laws that govern the generation of such different, unpredictable feelings from a single first feeling.
But it does seem to me that something is in fact hidden from us, because our imagination cannot pass from one kind of sensation to another which we have never experienced. A person born blind never gains an image of colours with the help of the other senses. Generally speaking, it is impossible for anyone born without one of his senses to use the sensations of the other senses, even if they are particularly powerful in him, to form an image of the sensations he has never experienced. It appears undeniable therefore that at least external, acquired sensations have something incommunicable, and are completely separate from each other. Their noticeable simplicity would lead to the same conclusion.

889. On this basis, it seems to me that the first subjective element is the pleasure diffused in the sensitive parts of a body animated by the fundamental feeling. The nature of this pleasure, produced by our body, is determined by the state of our body itself, granted the presence of life.
The modifications of the fundamental feeling are certainly determined by the state of our body but, as I have said, to investigate the laws governing this fact is beyond my powers.

890. Because the various parts of the body have a different state, they receive impressions in a different way, and modify the fundamental feeling differently. This varying state of the parts of the body was wisely ordained by the Creator in such a way that different organs were fittingly designed to determine various kinds of sensations. Hence the wonderful structure of the eye is designed to receive certain modifications of feeling different from those received in the ears, nose and palate.

891. Besides the modifications of the fundamental feeling presented by these sensories, modifications also take place in different parts of the body, according to their constitution and composition, or according to some particular organisation. The sense of hunger, of thirst and of sleep, of the sexual drive, are all different in kind. But they are not considered as senses because the particular name of sense is reserved for what helps our understanding in a very special way to acquire cognitions of external things.

892. The special condition and organisation of each senseorgan makes it capable of receiving the particular kind of modification of the fundamental feeling for which it was designed. However, the modification does not take place unless, in addition to a good organic system, a stimulus acts in the appropriate way. Light is needed if the eye is to give colour-sensations; hearing needs air, the nose needs odour-particles and the palate taste-particles. There has to be an appropriate, suitable cause relevant to both the matter and form of the organ, so that the organ can undergo the change necessary for bringing about a particular kind of sensation in the fundamental feeling.

893. A simple cause however is not enough; it must also act in the particular way necessary for stimulating each of the four senses.(187)

894. Thus, to produce special sensations, three things are necessary, in addition to life: 1. the quality of suitable organisation, and the condition of the organ; 2. the right kind of agent; 3. an appropriate manner of action by the agent.

895. Consequently the effect, or subjective sensation, produced simultaneously by these three principles, is certainly not an indication of the condition of one of them only. It is a mistake to think we can establish the quality of the external cause from the subjective sensation.
For example, the sensation of heat is subjective; it is in us, not in the external body producing it [App., no. 32]. It is not therefore a suitable measure of the quantity of heat. We can be persuaded of this if we put a very cold hand into water that is not so cold; the water will seem warm. The same will happen when a hand that feels very hot is immersed in lukewarm water; the water seems cold. The reason is the different state of the hand due to the necessary change in the fundamental feeling.

896. Although we have seen that the elementary sensations of touch and the particles corresponding to them are extended and continuous, we cannot conclude with certainty that touch can perceive every minute extension.
It is true that every space assignable in an elementary, continuous sensation must be felt; but we cannot attribute to each tiny space considered in itself what is said about it considered as an ideal part of the continuum.
There could be a law stating that sensation never takes place below a certain minimum extension. If so, observation in this case is powerless to affirm anything with certainty except about possibilities or probabilities. For instance, there is no contradiction in affirming on the one hand that we can think of an indefinitely small sensation and on the other that such a sensation must necessarily have some extension. Because we cannot reasonably exclude either of them, their possibility must be granted.

897. However, whether sensation is of such a nature that its extension can be reduced indefinitely, or whether it has a minimum extension, there seems no doubt at all that it is usually much more acute than our awareness of it. As a result, sensation feels spaces so minute that we are not aware of feeling them.(188)
The fact that the sensation of touch is far more refined than our awareness of the sensation is evident in those born blind. It is commonly said that their sense of touch is more acute. It is known that they can distinguish coins, playing cards, the quality of cloth and even colours by touch alone; they can sense the breathing or movement of anyone silently approaching them, even at a distance. They can indeed do wonderful things with their sense of touch, but not, I think, because it is more acute in them or because nature has endowed them better. What has been developed is their awareness about sensations. Their sense of touch is the same as that of others, who may or may not be blind.(189) But blind people, not having the distractions of sight, need to profit from their sensations of touch. They acquire very sensitive attention and concentration relative to all the different impressions on their touch, including delicate impressions which escape other people. It is not exaggerated, therefore, to believe that if awareness could make even further progress, human beings would realise that their touch, although limited, is a sense of unbelievable delicacy [App., no. 33].

898. As we have observed, it is more difficult to be aware of sensations when they are motionless and hardly change. When we wish to note the unevenness of a surface with our hand, it is not sufficient to press our finger on one spot only. We may feel the minute differences in the surface but not be aware of feeling them. To be aware of them we move our finger firmly over the surface. Because this action affords us sharper sensations of the uneven surface, it is easy to be aware of them and, through them, of the unevenness.

899. Hence a solid body, in so far as we are aware of feeling it, is different from one we actually feel by touch. The body we are aware of may perhaps be perfectly continuous and smooth on the surface, while the body we touch is possibly uneven, with high and low points, as any powerful microscope will reveal. As I have said, it seems we cannot put a limit to the acuteness of our touch. The microscope, while revealing the high and low points of the surface, also reveals the body as joined at several places and composed, too, of small, apparently continuous spaces. This is not the continuity of elementary bodies we have spoken about, a continuity which we believe escapes the most acute attention. Nor can we call it true continuity, because elementary bodies can be so close to each other that we cannot observe any interval between them. Nevertheless, the perfect adhesion of elementary bodies is not impossible or absurd, in my opinion, for there is nothing impossible about a true contact.

900. But let us leave this dangerous, unobservable world. A solid body perceived by touch and adverted to, has a shape we can distinguish fairly well. We ignore the unevenness of the surface and use our imagination to shape the body in the way we find most convenient for mentally conceiving it. This explains the regularity of shapes offered by touch. We perceive them easily because of their simplicity, which presents enough distinction and information for our purposes; we are quite satisfied.(190)

901. Our eye perceives light directly and light informs us about external things [App., no. 34]. I am concerned with the eye only in so far as it perceives light, its immediate agent, not as it indicates distant bodies that do not touch it. We have seen that the three parts of the extrasubjectivity of our senses are force, multiplicity and extension.
Force is felt equally by all the senses, has the general concept of agent only and in itself presents nothing determinate. We must now see how we perceive, with the other four senses, multiplicity and extension, the parts that in some way determine the agent's nature.

902. As regards extension, we note that the four senses are touched and affected by bodies so minute that if one alone were to strike our senses, it would be impossible to isolate and observe it. No one can see or touch particles of light or fire or air or smell or molecules of food stimulating our sense of taste, because they are so tiny that we cannot note or advert to them.
As regards multiplicity, we find particles crowding in on our organs in such numbers that even if we could identify their size, we could never determine their number clearly.

These two circumstances, that is, the size, shape, movement and changes that cannot be observed in the particles, and their uncountable number must cause a vivid but confused perception in us of the mass of particles. The extrasubjective part of the four organs under discussion must be, as it were, blind, and lacking in differentiation [App., no. 35]. Hence, although the extrasubjective part of these sensations is vivid, they offer to our understanding little that is clear about their immediate agents, and seem to present something more mysterious than what is offered by the sense of touch. In fact, when the understanding receives only a few clear perceptions, mystery seems inevitable. We should also note that the understanding takes its perceptions from the extrasubjective part of sensations which, confused at its origin, renders our intellections confused and vague.

903. The difference of these four organs from touch should be carefully noted. Touch perceives larger solid bodies;(191) the particles of such bodies adhere to each other either through real contact or very close proximity (I believe both cases are true). They therefore present to touch a large, single shape, with the intervening spaces and high and low points escaping observation. Thus the extension of large agents acting on the sense of touch is easily identified and their regular shape easily conceived. On the other hand, the particles that impinge on and stimulate the four senses, are scattered, indefinable, moving at great speed, never remaining in the same place or state or maintaining the same shape. They move about haphazardly in all directions, disappearing in the air on which they arrived. In short, even if they were only small in quantity and of a size we could advert to, they would still escape observation because of the tremendous speed and instability of their continual movements.

904. Another comment must be made which will clearly demonstrate that the immediate agents of the four organs are of such a kind that their size and shape cannot be observed(192) nor present us with a distinct perception. Without this perception, all the sensations of the four organs will necessarily be confused, and therefore, mysterious, although pleasant and vivid.(193)

We have distinguished two parts, subjective and extrasubjective, in adventitious sensations, and have seen that an external body can make an impression and stimulate a sensation on any sensitive part of our body. We have also seen that the affected part must be distinguished from its surrounding parts into which the movement, together with the sensation, sometimes spreads in sympathy. But this kind of sensation, spreading from the touched parts, contains nothing extrasubjective, because the spread and communication of the movement experienced by the sensitive nerve differs from the impulse or kind of disturbance initially experienced by the nerve. The disturbance causes the nerve to pass from rest to excitation. This first impression or disturbance indicates that a force has been applied, while on the other hand the communication and continuation of the movement present no new disturbance or force, except that of the parts themselves of the nerve. These parts pass the movement to each other through the force they have received proper to them. But because this force passes from one part of the nerve to the other, it follows, as I have already said, that the whole sensation propagated by sympathy can be referred only to that feeling part of our body which allows movement of the parts and feeling to pass through it. The increase of the sympathetic sensation is subjective only, or at least certainly not united with the perception of an external body; it remains in the stimulated nerve as in its source and matter.

905. The special nature of the four organs must be now noted. A single particle of air vibrating in the ear could definitely not produce a sensation of sound; only the entire body of undulating air causes this sensation. In the same way, although I do not know if a single unit of light could move the visual organ, I do believe that, in order to have a sensation of colour, a certain quantity of light must act upon our eyes.

Similarly it seems to me that a sensation of taste or smell is not aroused by virtue of small, flavoured or odorous bodies but by great numbers of particles striking the taste buds and nostrils and causing such a movement that they produce a frequent, general vibration which alone occasions the sensations. If this is the case, and it seems probable to me, we can no longer say that each one of the minute acting particles must have produced some sensation of taste, smell, etc. All we can say is that each tiny body, despite its minute size, has made its impact. But this is not yet sensation. Taste, smell and other sensations begin only when the vibration along the length of the nervous membrane or cartilage has been propagated and reached the level of agitation required for the sensation to take place.

If this is the case (and it cannot be doubted relative to hearing), I believe that the four kinds of sensations would generally take place through sympathy among the parts, that is, through communication of movement. This would make the extrasubjective part of the sensations still more hidden and confused. We would be dealing with unobservable parts, and the sensation would be stimulated not so much by the impulse they imparted, as by the agitation following in the affected part of our body. If both impulse and consequent agitation together gave sensation, one mixed with the other would be almost indiscernible.

Notes

(185) These determinations explain the element we have so far ignored in order not to complicate the argument. It has been included in the word 'corporeal', used to qualify 'force'.

(186) The true part of the ancient opinion that phantasms are likenesses or images of external bodies is therefore the extrasubjective part with which external bodies are perceived, not the subjective part. Hence the multiplicity and continuity of phantasms are similar to those of external bodies. The force proper to external bodies is, however, experienced by us passively in phantasms although it is active in bodies. Nevertheless, it is the same force in act in us and in bodies because sensations are its term and direct effect.

(187) In the sense of touch there are a great variety of sensations according to the type of touch. Without previous experience, no one could imagine the peculiar sensation of tickling, a sensation that makes us laugh even against our will and has no connection with any other sensation.

(188) This further emphasises the distance between sensation and understanding; awareness is an act of understanding, not of feeling. Awareness is only intellective attention given to what we feel or understand. Because the ancients had clearly seen that reflection is an act of understanding, not of feeling, they sometimes characterised the intellective faculty by reflection. We see this in Dante, where he mentions the three powers of living, feeling and understanding: ... a single soul which lives, feels and continually turns upon itself.

(189) We must also note that animals have a certain power over their nerves. With this power they extend and apply their nerves to receive sensations better. Its use can be perfected by skill and by habit.

(190) The mind has no difficulty in grasping regular shapes, like triangles, squares and any figure with a perceptible number of sides, because their component elements are few. On the other hand, if we greatly increase the number of sides, we can no longer advert to them, although we perceive them all equally with our sense. If the sides are of varying length, it is even more difficult to have a distinct idea. Imagine that the surfaces of a solid are all different from each other. The differences and multiplicity are beyond the power of our attention. The shape is too complex for our mind because it is conceived only by means of conceiving the unity of the parts. These, however, are so many and different that we are unable to keep them simultaneously before our mind, or to give them the amount of attention we could pay to a smaller number.

(191) Even liquids, in so far as they act on the sense of touch, occupy a definite solid space, and present precise, determinate shapes to our observation because, although mobile, they are nevertheless stable, large and regular.

(192) It is size and shape that give us a distinct perception of an agent, as we have already said, because they are the extrasubjective parts of sensation.

(193) How vivid they are depends on the particles producing a strong impression in the organ through their vast number, speed and perhaps, in the case of light, their elasticity, for light impinges and rebounds in the briefest of time without a very strong impression. The result of any strong impression must be a pronounced movement or perhaps a vibration of the nerves causing a large subjective sensation, as the soul feels the effect of the quivering nerve. In general we can establish the following fact given by observation: 'A very pleasant sensation is produced in a nerve when it is stimulated by rapid, frequent vibrations which do not damage or sever the nerve.' Now every time the stimuli are very small and many, they can do this, provided their number is not excessive and their impact moderate. Thus a carpet of roses or any soft material is very pleasant to lie on, and every soft surface is pleasant to our touch, in the same way that gentle colours can please our eyes and faint sounds our ears.