Eye lines of sight

The drawing depicts a circular cross-section of the eyeball with an inner circle representing the pupil or crystalline lens. A series of straight lines radiate from the front of the eye to various points in space, each labeled with a character to demonstrate the field of vision and the geometry of sight. This ink sketch represents the artist's empirical investigation into the mechanics of optics and how the eye receives light.

This diagram belongs to Leonardo’s broader study of 'perspectiva,' the medieval and Renaissance science of optics that bridged natural philosophy and art. It reflects the transition from classical theories of 'extramission' (light coming from the eye) to a more modern understanding of light entering the eye, a concept central to the Neoplatonic idea of light as a primary mediator of divine knowledge.