Why Not to Paint Leaves Transparent to the Sun
Dark low branches, the habits of twigs and heavy-fruited boughs, and a leaf's three accidents
A page of the Treatise on Painting continuing the study of foliage. It advises setting dark low branches against illuminated greenery, and warns ([892]) never to paint leaves made transparent by the sun, because the sharp cast shadow of an overlying leaf printed on a transparent one makes the branchwork confused. Short observations labelled c, d, e note how upper twigs hug the master branch, how a leaf lit at unequal angles is less transparent, and how boughs bearing heavy fruit such as walnuts and figs bend to the ground; a final chapter ([893]) describes the leaf's three accidents of shadow, sheen and transparency, illustrated by a small pen diagram.
On this page
Dark low branches against lit greenery
It is very useful to paint some low branchings that are dark and stand out against illuminated greenery somewhat set back from the foremost masses. Of dark greenery seen from below, the darkest part is the one nearest the eye, that is, the part farthest from the luminous air.
Never depict leaves transparent to the sun [892]
Leonardo forbids painting leaves made transparent by the sun because they read as confused: onto the transparency of one leaf is printed the sharp-edged, firmly dark shadow of another leaf lying above it, sometimes covering a half or a third of it. Such branchwork is muddled, and its imitation is to be avoided.
Habits of twigs, angles and heavy boughs (c, d, e)
Three lettered notes: (c) the upper twigs of a plant's side branches keep closer to their master branch than those below; (d) a leaf that takes the light at more unequal angles is less transparent; (e) the lowest branches of plants bearing large leaves and heavy fruit, like walnuts and figs, always bend down toward the earth.
The three accidents of a leaf: shadow, sheen, transparency [893]
A leaf can show three accidents at once, shadow, sheen and transparency. With the light at n on leaf s and the eye at m, the eye sees a illuminated, b shaded and c transparent. A small pen diagram beside the text lays out the leaf with these letters.