CHAPTER XI

TOUCH. ONE SENSE OR MANY?

ITS MEDIUM

             THE same reasoning holds for the tangible and touch. If touch is not one sense, but several, then the tangible sense-objects must necessarily be several. But it is a problem whether it is one sense or several: and what the organ is--whether it is the flesh, or what corresponds to flesh in other [animals], or not; and if not, then this [flesh] would be the medium, while the primary sense organ would be something else within.§§ 517-18

             For every sense seems to be of a single contrariety, as sight of white and black, hearing of high and low, taste of sweet and bitter. But in the tangible order there are several contrarieties, hot and cold, dry and wet, hard and soft, and the like.§ 519

             Here is a partial solution of this problem: that in other senses also there are several contraries; as in voice there is not only high and low but also loud and soft, smooth and rough, and other such qualities. There is also a like variety of differences in colour.§ 520

             But it is not clear what is the underlying unity of touch, as sound is of hearing.§§ 521-4

             It is not evidence as to whether the sense-organ is interior or is the flesh, immediately, that the sensation arises simultaneously with contact. For if, as things are, one were to stretch a covering or membrane over the skin, a sensation would still arise immediately on making contact; yet it is obvious that the sense-organ was not in this membrane. And if it were ingrown the sensation would reach the sensorium even sooner.§§ 525-6

             Therefore it appears that the relation of this part of the body [to the whole] is comparable to that which air would have if it formed a natural covering that grew all round our bodies. For then it would appear that we perceived sound and odour and colour through some one common medium, and even that there were but one sense for hearing, seeing and smelling. Since in fact, however, there exists something definite through which the motions [of these senses] are produced, it is evident that each of these senses is diverse. But in the case of touch, this is still far from clear. It is impossible that an animated body be constituted from air or water, for it must be solid. It can, then, only be a mixture from earth and the other elements, as flesh (or its counterpart) requires. Wherefore it is necessary that the medium of touch be a body conjoined [to the organism] through which its sensations, which are several, may come about.§§ 527-8

             That they are several is proved by the fact that there is touch in the tongue; for that same member feels all kinds of tangible objects, as well as savours. If every part of the flesh perceived savours it would seem that touch and taste were one and the same. But we know that they are two, in that one organ cannot be substituted for the other.§ 529