On Sense and The Sensible
by Aristotle
Written circa 350 B.C.
Translated by J. I. Beare
Part 2
Democritus, on the other hand, is right in his opinion that the eye is of
water; not, however, when he goes on to explain seeing as mere mirroring. The
mirroring that takes place in an eye is due to the fact that the eye is smooth,
and it really has its seat not in the eye which is seen, but in that which
sees. For the case is merely one of reflexion. But it would seem that even in
his time there was no scientific knowledge of the general subject of the
formation of images