CHAPTER I

IS THERE A SIXTH SENSE?

THE 'COMMON' SENSE-OBJECTS

             THAT THERE IS NO OTHER SENSE BESIDES THE FIVE enumerated--I mean, sight, hearing, smell, taste, touch--is tenable for the following reasons:§ 564-7

             For if we have sensation of all the objects of the sense of touch (all varieties of the tangible being in fact perceptible by us through touch) then, if we lack some [class of] sensation, we must be lacking also in some sense-organ. Now whatever we perceive by contact is perceptible to us through that sense of touch which we do in fact possess. But whatever we perceive through a medium and without contact is perceived through intervening simple elements (I mean such as air and water); and [in this case] things are so disposed that if several sense-objects, differing generically from one another, are perceptible through one medium, then, necessarily, what has a sense-organ of this kind can perceive either object--e.g. if the organ is constituted of air, then air is medium for both colour and sound. But if there are several media for the same sense-object, as air and water are for colour (both being transparent), what is possessed of either [medium] alone will perceive what comes through either or both. §§ 568-70

             The sense-organs are formed of these two simple bodies only, air and water. For the pupil is of water; the [organ of] hearing, of air; and smell of either. But fire is found in none, or is common to all; for nothing without heat is sensitive. Earth either belongs to none, or is especially involved in touch. Whence it remains that there is no sense-organ without air and water, Now these organs certain animals do in fact possess. All the senses therefore are found in animals neither incomplete or defective (for even the mole is observed to have eyes beneath its skin). Therefore, if there is no other kind of body, and no qualities other than those of the bodies here present no sense will be lacking to any [such] animal. § 571-4

             But there cannot be a sense proper to the common qualities which we perceive by any one sense, yet not incidentally merely: such as movement, rest, shape, size, number, unity.§§ 575-6

             For we know all these by motion: that is, we know size by movement and from size, shape; for shape is itself a kind of size.§ 577

             What is at rest we know as not moving, and number as the negation of continuity and identity. For each sense perceives some one thing, so that it is impossible that there should be a sense specially adapted to any of these. § 578

             The situation would, in that case, be as when we perceive what is sweet by sight. This happens because we take account of the sensation of both these, so that when they coincide we are aware of it. If it were not so, we should perceive this only incidentally, as when we see the son of Cleon not as the son of Cleon but as something white; with which object there happens to coincide the fact of being the son of Cleon. But we have a general sense for common qualities, and this not merely incidentally. Hence, there is not a proper sense [for them]. [If there were] we should never perceive them except in the way we have said that we see the son of Cleon. The senses perceive incidentally what is proper to one another; [perceiving] not in their specific capacity, but in so far as they form one sense,--as in the perception of bile as both reddish in colour and bitter. It does not pertain to either sense to judge that these are qualities of one thing. Hence arises the mistaken view that, if a thing is reddish, it is bile.§§ 579-81

             One might ask why we have several senses and not one only. Is it in order that the common qualities, which are consequent on the proper, should be less obscure--movement, dimension, number? For if there were no sense but sight alone, and that only of white as an object, these qualities would certainly be very obscure to the apprehension, and all things would appear alike, because colour and dimension always accompany each other. But the fact that there are common qualities attained by various senses, makes it evident that each of them is a distinct object.§§ 582-3