Table of Contents for a Treatise on Optics and Painting
Chapter headings on mirrors, the eye and the visual pyramid, and on shadow, reflected light and aerial perspective
This torn, L-shaped fragment is not a finished text but a syllabus: two columns of chapter headings for a projected treatise on vision and painting. The left column poses questions of optics - why mirrored images invert or change size, how the pupil contracts in light, why the visual pyramid comes to a point in the eye and bends on entering water, and even how the sun's or a planet's size might be gauged through thick and thin air. The right column, headed 'Of painting', lists topics on where shadows should be dark or middling, on reflected lights and glimmers, and on aerial perspective, noting that distant things appear dazzled and finally blue. Some lines are lost to damage, and marginal letters such as (q), (p) and (v) mark cross-references.
On this page
Syllabus of optics: mirrors, the pupil and the visual pyramid
Chapters ask why mirrored things appear inverted, larger or smaller, which mirror shows things exactly and which shows them outside itself, and how the mirror is the master of painters. Others treat why the pupil shrinks in light and grows in dark, and how the pyramidal lines from the eyes come to a point in the thing seen.
Refraction in water and measuring the sun through layered air
One chapter notes that the visual pyramid reaching a thing set in water has its lines twist and lose their straightness. Another proposes to know the size of the sun or of another planet, which cannot be measured among us, by reasoning about the pyramid passing through two conditions of air - thick and thin.
Chapters on shadow, reflected light and aerial perspective
Under 'Of painting' Leonardo lists where shadows must be dark, middling or the lights bright, where glimmers and reflections fall, and how to portray things from nature. He notes that figures show little variation of light and shade in troubled air or at sunset, and that distant things appear dazzled and, at the ultimate distance, blue (p).