Alcibiades. What meaning? what have you in your thoughts, Socrates, when you ask the question?
Socrates. I will tell you what I suspect this inscription means, and what particular thing it advises us to do. For a just resemblance of it is, I think, not to be found wherever one pleases, but in only one thing, the sight.
Alcibiades. How do you mean?
Socrates. Consider it jointly with me. Were a man to address himself to the outward human eye, as it were some other man; and were he to give it this counsel, "See yourself," what particular thing should we suppose that he advises the eye to do? Should we not suppose that it was to look at such a thing as that the eye by looking at it, might see itself?
Alcibiades. Certainly we should.
Socrates. What kind of thing then do we think of by looking at which we see things at which we look, and at the same time see ourselves?
Alcibiades. 'Tis evident, Socrates, that for this purpose we must look at mirrors and other things of like kind.
Socrates. You are right. And has not the eye itself, with which we see, something of the same kind belonging to it?
Alcibiades. Most certainly it has.
Socrates. You have observed then, that the face of the person who looks in the eye of another person, appears visible to himself in the eye of the person opposite to him, as in a mirror. And we therefore call this the pupil, because it exhibits the image of that person who examines it.