Shadows of Leafy Branches and the Darkest Part of a Bough
Part Six of the Treatise on Painting: light and shade in distant foliage, with a marginal optical diagram
A page from the sixth part of the Treatise on Painting, treating the light and shade of leafy branches seen at a distance. Leonardo explains why, far off, the illuminated parts of a bough overwhelm and confuse its shadows, and states that the darkest part of a branch is the one furthest from its extremities; a further chapter on the view of trees begins at the foot. A small pen diagram in the top margin, showing an eye with lines converging on three circles, illustrates where light and shade are seen.
On this page
Why the shadows of leafy branches weaken with distance
At a great distance the illuminated part of a tree's branches confuses the shadows that lie among the lit clusters. The lit parts grow in apparent size while the shadows shrink below the threshold of sight, so the mixed images reaching the eye read as a confused whole that takes on the character of the branch's brighter, better-preserved parts.
Which part of a branch appears darkest
Leonardo states that the darkest part of a plant's branch is the portion furthest from its extremities, provided the tree has a uniform distribution of branching. The rule ties the depth of shade to distance from the outer tips of the foliage.
Marginal light-and-shade demonstration figure
The chapter is proved 'by the figure in the margin.' The pen sketch at the top of the sheet shows an eye, labelled at its apex, from which lines fan out to three small circles, diagramming how the eye sees both the light and the shade of the bodies before it.