Knowing through the Eye. Leonardo da Vinci’s Imprensiva and Alhazen’s Intuitio

Leonardo da Vinci’s definition of the first brain ventricle as the imprensiva was highly unorthodox in light of the late medieval and Renaissance philosophical and medical tradition. The term itself, imprensiva, seems to be a neologism forged by Leonardo, and he never clearly defined its functions in his surviving annotations. This study offers a global assessment of Leonardo’s ideas on knowledge by exploring the varied ways in which he interpreted the imprensiva in the course of his long career. Essential to understanding Leonardo’s reliance on the eye not only as a conveyor, but also as a ‘processor’ of knowledge is Alhazen’s concept of intuitio: a verification procedure through which the eye validates, corrects, and construes the data channeled through vision almost in no time. Relying on both a detailed scrutiny of Leonardo’s anatomical drawings in connection with the brain and a careful analysis of Leonardo’s philosophical and medical sources, this essay demonstrates not only the huge extent but also the limits of Leonardo’s use of the image as the most accurate source of knowledge, superior to any form of verbal account