Democritus explains sight by the visual image, which he dexcribes in a
peculiar way; the visual image does not arise directly in the pupil, but the
air between the eye and the object of sight is contracted and stamped by the
object seen and the seer; for from everything there is always a sort of
effluence proceeding. So this air, which is solid and variously colored,
appears in the eye, which is moist (?); the eye does not admit the dense part,
but the moist passes through...