BEGINNING OF THE DISCUSSION OF THEAETETUS' FIRST ANSWER

'Just consider! Which of the two answers better fits the facts: the eyes are that, ᾧ ὁρῶμεν ἢ δι᾽ οὗ, that which carries out the seeing, or, that through which the seeing occurs?'

The corresponding question for hearing and the ears, ('ᾧ' is ambiguous; 'through' does not give the meaning. Therefore we say for ᾧ 'what': what does the perceiving, as distinct from 'through which'.)

The essential determination of eye, nose, ear, tongue, thus depends on whether these themselves carry out the perception and are at work as it were, or whether they are such that perception occurs in passing through them. Theaetetus admits that the second characterization is more accurate.

Why should this be so? Theaetetus himself does not give the reason, but passes the problem over to Socrates. The proof provided is in its external form indirect, for the matter leads Plato to a fundamental reflection. To understand this, to draw out everything from it pertaining to the leading problem, we must, here as elsewhere, put aside the problematics and advances of contemporary disciplines like psychology (especially psychology). Instead, we shall call upon the unprejudiced pre-scientific everyday self-understanding of man on the one hand, and upon a clear and expansive philosophical mode of questioning on the other. Both are still missing in what is familiar to us as 'psychology'.

The thesis, also conceded by Theaetetus, runs as follows: the eye (ear and so forth) is such that we perceive in passing through it (δι᾽ οὗ); it is not that which performs the perception. The proof is indirect, i.e. the contrary of the asserted thesis is assumed, and the consequences of this assumption are then followed through and checked against the facts. Assuming, therefore, that it is the eye, ᾧ, i.e. that the eye is not that through which we see but is that which performs the seeing, then we must make the corresponding assumption in regard to the nose, tongue, hand etc. Thus the ear would be what performs the hearing. The eye would come into a relationship with colour, the ear into a relationship with sound, the nose into a relationship with smell, the tongue into a relationship with taste, the hand into a relationship with touch. What does all this amount to? Let us make the situation quite clear! Eyes, ears, nose, tongue, hand, are all situated at various points on the human body such that each is concerned with its own respective perceptual object. Accordingly, the colours seen by the eyes, the sounds heard by the ears, the smells etc. are distributed over the corresponding points of the body. The individual perceptual objects