To the question whether the organ of touch lies inward or not (i. e. whether we need look any farther than the flesh), no indication in favour of the second answer can be drawn from the fact that if the object comes into contact with the flesh it is at once perceived. [423a] For even under present conditions if the experiment is made of making a web and stretching it tight over the flesh, as soon as this web is touched the sensation is reported in the same manner as before, yet it is clear that the organ is not in this membrane. If the membrane could be grown on to the flesh, the report would travel still quicker. (5) The flesh plays in touch very much the same part as would be played in the other senses by an air-envelope growing round our body; had we such an envelope attached to us we should have supposed that it was by a single organ that we perceived sounds, colours, and smells, and we should have taken sight, hearing, and smell to be a single sense. But as it is, because that through which the different movements are transmitted is not naturally attached to our bodies, (10) the difference of the various sense-organs is too plain to miss. But in the case of touch the obscurity remains.
There must be such a naturally attached ‘medium’ as flesh, for no living body could be constructed of air or water; it must be something solid. Consequently it must be composed of earth along with these, which is just what flesh and its analogue in animals which have no true flesh tend to be. (15) Hence of necessity the medium through which are transmitted the manifoldly contrasted tactual qualities must be a body naturally attached to the organism. That they are manifold is clear when we consider touching with the tongue; we apprehend at the tongue all tangible qualities as well as flavour. Suppose all the rest of our flesh was, like the tongue, (20) sensitive to flavour, we should have identified the sense of taste and the sense of touch; what saves us from this identification is the fact that touch and taste are not always found together in the same part of the body. The following problem might be raised. Let us assume that every body has depth, i. e. has three dimensions, and that if two bodies have a third body between them they cannot be in contact with one another; let us remember that what is liquid is a body and must be or contain water, (25) and that if two bodies touch one another under water, their touching surfaces cannot be dry, but must have water between, viz. the water which wets their bounding surfaces; from all this it follows that in water two bodies cannot be in contact with one another. The same holds of two bodies in air—air being to bodies in air precisely what water is to bodies in water—but the facts are not so evident to our observation, (30) because we live in air, just as animals that live in water would not notice that the things which touch one another in water have wet surfaces. [423b] The problem, then, is: does the perception of all objects of sense take place in the same way, or does it not, e. g. taste and touch requiring contact (as they are commonly thought to do), while all other senses perceive over a distance? The distinction is unsound; we perceive what is hard or soft, (5) as well as the objects of hearing, sight, and smell, through a ‘medium’, only that the latter are perceived over a greater distance than the former; that is why the facts escape our notice. For we do perceive everything through a medium; but in these cases the fact escapes us. Yet, to repeat what we said before, if the medium for touch were a membrane separating us from the object without our observing its existence, (10) we should be relatively to it in the same condition as we are now to air or water in which we are immersed; in their case we fancy we can touch objects, nothing coming in between us and them. But there remains this difference between what can be touched and what can be seen or can sound; in the latter two cases we perceive because the medium produces a certain effect upon us, whereas in the perception of objects of touch we are affected not by but along with the medium; it is as if a man were struck through his shield, (15) where the shock is not first given to the shield and passed on to the man, but the concussion of both is simultaneous.
In general, flesh and the tongue are related to the real organs of touch and taste, as air and water are to those of sight, hearing, and smell. Hence in neither the one case nor the other can there be any perception of an object if it is placed immediately upon the organ, (20) e. g. if a white object is placed on the surface of the eye. This again shows that what has the power of perceiving the tangible is seated inside. Only so would there be a complete analogy with all the other senses. In their case if you place the object on the organ it is not perceived, here if you place it on the flesh it is perceived; therefore flesh is not the organ but the medium of touch. (25)
What can be touched are distinctive qualities of body as body; by such differences I mean those which characterize the elements, viz. hot cold, dry moist, of which we have spoken earlier in our treatise on the elements.41 The organ for the perception of these is that of touch—that part of the body in which primarily the sense of touch resides. (30) This is that part which is potentially such as its object is actually: for all sense-perception is a process of being so affected; so that that which makes something such as it itself actually is makes the other such because the other is already potentially such. [424a] That is why when an object of touch is equally hot and cold or hard and soft we cannot perceive; what we perceive must have a degree of the sensible quality lying beyond the neutral point. This implies that the sense itself is a ‘mean’ between any two opposite qualities which determine the field of that sense. It is to this that it owes its power of discerning the objects in that field. (5) What is ‘in the middle’ is fitted to discern; relatively to either extreme it can put itself in the place of the other. As what is to perceive both white and black must, to begin with, be actually neither but potentially either (and so with all the other sense-organs), so the organ of touch must be neither hot nor cold.
Further, as in a sense sight had42 for its object both what was visible and what was invisible (and there was a parallel truth about all the other senses discussed),43 (10) so touch has for its object both what is tangible and what is intangible. Here by ‘intangible’ is meant (a) what like air possesses some quality of tangible things in a very slight degree and (b) what possesses it in an excessive degree, as destructive things do.
We have now given an outline account of each of the several senses. (15)
12 The following results applying to any and every sense may now be formulated.
(A) By a ‘sense’ is meant what has the power of receiving into itself the sensible forms of things without the matter. This must be conceived of as taking place in the way in which a piece of wax takes on the impress of a signet-ring without the iron or gold; we say that what produces the impression is a signet of bronze or gold, (20) but its particular metallic constitution makes no difference: in a similar way the sense is affected by what is coloured or flavoured or sounding, but it is indifferent what in each case the substance is; what alone matters is what quality it has, i. e. in what ratio its constituents are combined.
(B) By ‘an organ of sense’ is meant that in which ultimately such a power is seated.
The sense and its organ are the same in fact, (25) but their essence is not the same. What perceives is, of course, a spatial magnitude, but we must not admit that either the having the power to perceive or the sense itself is a magnitude; what they are is a certain ratio or power in a magnitude. This enables us to explain why objects of sense which possess one of two opposite sensible qualities in a degree largely in excess of the other opposite destroy the organs of sense; if the movement set up by an object is too strong for the organ, (30) the equipoise of contrary qualities in the organ, which just is its sensory power, is disturbed; it is precisely as concord and tone are destroyed by too violently twanging the strings of a lyre. This explains also why plants cannot perceive, in spite of their having a portion of soul in them and obviously being affected by tangible objects themselves; for undoubtedly their temperature can be lowered or raised. [424b] The explanation is that they have no mean of contrary qualities, and so no principle in them capable of taking on the forms of sensible ob
jects without their matter; in the case of plants the affection is an affection by form-and-matter together. The problem might be raised: Can what cannot smell be said to be affected by smells or what cannot see by colours, (5) and so on? It might be said that a smell is just what can be smelt, and if it produces any effect it can only be so as to make something smell it, and it might be argued that what cannot smell cannot be affected by smells and further that what can smell can be affected by it only in so far as it has in it the power to smell (similarly with the proper objects of all the other senses). Indeed that this is so is made quite evident as follows. Light or darkness, (10) sounds and smells leave bodies quite unaffected; what does affect bodies is not these but the bodies which are their vehicles, e. g. what splits the trunk of a tree is not the sound of the thunder but the air which accompanies thunder. Yes, but, it may be objected, bodies are affected by what is tangible and by flavours. If not, by what are things that are without soul affected, i. e. altered in quality? Must we not, then, admit that the objects of the other senses also may affect them? Is not the true account this, that all bodies are capable of being affected by smells and sounds, but that some on being acted upon, (15) having no boundaries of their own, disintegrate, as in the instance of air, which does become odorous, showing that some effect is produced on it by what is odorous? But smelling is more than such an affection by what is odorous—what more? Is not the answer that, while the air owing to the momentary duration of the action upon it of what is odorous does itself become perceptible to the sense of smell, smelling is an observing of the result produced?
* * *
1 sc. in the sense of form.
2 viz. organized, or possessed potentially of life.
3 i. e. instrument.
4 Being an artificial, not a natural, body.
5 i. e. which states what it is to be an eye.
6 Though only potentially, i. e. they are at a further remove from actuality than the fully formed and organized body.
7 i. e. to the second grade of actuality.
8 i. e. to the first grade of actuality.
9 i. e. actuator.
10 i. e. it has nothing in it corresponding to a middle term.
11 iii. 12, esp. 434a 22–30, b10 ff.
12 iii. 12, 13.
13 412a 7.
14 413a 23–5, b11–13, 21–4.
15 413b 32–414a 1.
16 c. 11. iii. 12. 434b 18–21.
17 iii. 3, 11. 433b 31–434a 7.
18 iii. 12, 13.
19 Cf. iii. 4–8.
20 sc. ‘which we shall see to be inseparable from nutrition’.
21 There is an unbroken current of the same specific life flowing through a discontinuous series of individual beings of the same species united by descent.
22 i. e. of itself.
23 i. e. the earliest and most indispensable kind of soul.
24 415b 24, cf. 410a 25.
25 De Gen. et Corr. 323b 18 ff.
26 Phys. 201b 31, 257b 8.
27 416a 29–b9.
28 viz. from ignorance or error to knowledge or truth.
29 iii. 4, 5.
30 417a 12–20.
31 Really, it is enough if it is perceptible by more than one sense.
32 422b 34 ff.
33 421b 13–422a 6.
34 i. e. it has air incorporated in its structure.
35 419b 6, 13.
36 i. e. when these bodies, e. g. the strings of a lyre, are actually sounding.
37 De Resp. 478a 28; P. A. 642a 31–b 4.
38 Cf. De Resp. 474b 25–9, 476a 6–15; P. A. 669a 2–5.
39 Because of the felt likeness between the respective smells and the really sweet or pungent tastes of the same herbs, &c.
40 sc. ‘and so, as we have seen, a being assimilated to’.
41 De Gen. et Corr. ii. 2, 3.
42 422a 20 ff.
43 421b 3–6, 422a 29.
BOOK III
1 That there is no sixth sense in addition to the five enumerated—sight, (20) hearing, smell, taste, touch—may be established by the following considerations:
If we have actually sensation of everything of which touch can give us sensation (for all the qualities of the tangible qua tangible are perceived by us through touch); and if absence of a sense necessarily involves absence of a sense-organ; and if (1) all objects that we perceive by immediate contact with them are perceptible by touch, (25) which sense we actually possess, and (2) all objects that we perceive through media, i. e. without immediate contact, (30) are perceptible by or through the simple elements, e. g. air and water (and this is so arranged that (a) if more than one kind of sensible object is perceivable through a single medium, the possessor of a sense-organ homogeneous with that medium has the power of perceiving both kinds of objects; for example, if the sense-organ is made of air, and air is a medium both for sound and for colour; and that (b) if more than one medium can transmit the same kind of sensible objects, as e. g. water as well as air can transmit colour, both being transparent, then the possessor of either alone will be able to perceive the kind of objects transmissible through both); and if of the simple elements two only, air and water, go to form sense-organs (for the pupil is made of water, the organ of hearing is made of air, and the organ of smell of one or other of these two, while fire is found either in none or in all—warmth being an essential condition of all sensibility—and earth either in none or, (5) if anywhere, specially mingled with the components of the organ of touch; wherefore it would remain that there can be no sense-organ formed of anything except water and air); and if these sense-organs are actually found in certain animals;—then all the possible senses are possessed by those animals that are not imperfect or mutilated (for even the mole is observed to have eyes beneath its skin); so that, (10) if there is no fifth element and no property other than those which belong to the four elements of our world, no sense can be wanting to such animals. [425a]
Further, there cannot be a special sense-organ for the common sensibles either, (15) i. e. the objects which we perceive incidentally through this or that special sense, e. g. movement, rest, figure, magnitude, number, unity; for all these we perceive by movement, e. g. magnitude by movement, and therefore also figure (for figure is a species of magnitude), what is at rest by the absence of movement: number is perceived by the negation of continuity, and by the special sensibles; for each sense perceives one class of sensible objects. (20) So that it is clearly impossible that there should be a special sense for any one of the common sensibles, e. g. movement; for, if that were so, our perception of it would be exactly parallel to our present perception of what is sweet by vision. That is so because we have a sense for each of the two qualities, in virtue of which when they happen to meet in one sensible object we are aware of both contemporaneously. (25) If it were not like this our perception of the common qualities would always be incidental, i. e. as is the perception of Cleon’s son, where we perceive him not as Cleon’s son but as white, and the white thing which we really perceive happens to be Cleon’s son.
But in the case of the common sensibles there is already in us a general sensibility which enables us to perceive them directly; there is therefore no special sense required for their perception: if there were, our perception of them would have been exactly like what has been above described.
The senses perceive each other’s special objects incidentally; not because the percipient sense is this or that special sense, (30) but because all form a unity: this incidental perception takes place whenever sense is directed at one and the same moment to two disparate qualities in one and the same object, e. g. to the bitterness and the yellowness of bile; the assertion of the identity of both cannot be the act of either of the senses; hence the illusion of sense, e. g. the belief that if a thing is yellow it is bile. [425b]
It might be asked why we have more senses than one. (5) Is it to prevent a failure to apprehend the common sensibles, e. g. movement, magnitude, and number, which go alo
ng with the special sensibles? Had we no sense but sight, and that sense no object but white, they would have tended to escape our notice and everything would have merged for us into an indistinguishable identity because of the concomitance of colour and magnitude. As it is, the fact that the common sensibles are given in the objects of more than one sense reveals their distinction from each and all of the special sensibles. (10)
2 Since it is through sense that we are aware that we are seeing or hearing, it must be either by sight that we are aware of seeing, or by some sense other than sight. But the sense that gives us this new sensation must perceive both sight and its object, viz. colour: so that either (1) there will be two senses both percipient of the same sensible object, or (2) the sense must be percipient of itself. Further, (15) even if the sense which perceives sight were different from sight, we must either fall into an infinite regress, or we must somewhere assume a sense which is aware of itself. If so, we ought to do this in the first case.
This presents a difficulty: if to perceive by sight is just to see, and what is seen is colour (or the coloured), then if we are to see that which sees, that which sees originally must be coloured. It is clear therefore that ‘to perceive by sight’ has more than one meaning; for even when we are not seeing, (20) it is by sight that we discriminate darkness from light, though not in the same way as we distinguish one colour from another. Further, in a sense even that which sees is coloured; for in each case the sense-organ is capable of receiving the sensible object without its matter. That is why even when the sensible objects are gone the sensings and imaginings continue to exist in the sense-organs. (25)
The Basic Works of Aristotle (Modern Library Classics) Page 82