Painters often deceive themselves, by representing water in which
they make the water reflect the objects seen by the man. But the
water reflects the object from one side and the man sees it from the
other; and it often happens that the painter sees an object from
below, and thus one and the same object is seen from hind part
before and upside down, because the water shows the image of the
object in one way, and the eye sees it in another.

Of rainbows and rain (479. 480).