Date: w. 1628, published in 1684, 1701

"We can best learn how mental intuition is to be employed by comparing it with ordinary vision."

— Descartes, René (1596-1650)

Date: 1692

"[T]he Explanation whereof is allowed by all men as satisfactory, 'tis this, in Tab. 41. Fig. 2. the Image a b of the Object A B is painted on the Retina inverted, and yet the Eye (or rather the Soul by means of the Eye) sees the Object erect and in its natural Posture."

— Molyneux, William (1656-1698)