Abstract

Examining various aspects of how Kepler’s discovery of retinal images was received in the field of philosophy, this article questions the meaning of the Keplerian dictum “ut pictura, ita visio”. In what sense could we say that vision is just like the physiological picture formed at the back of the eye? We show that with this question arises an opposition between two theoretical options – a tension that is rarely pointed out: The first option views physiological pictures (retinal or cerebral) as the proximal, internal objects of perception, inspected by the soul on the very body of the eye or brain, while the second considers that vision, although indexed on the picture, is never directed upon it, the picture being merely the causal antecedent of an act of direct perception of the external world.