Dark Leaves Before Transparent Ones, and the Colour of Foliage
Half-shaded leaves, young plants brighter in May, and greens turning to yellow against the air
A page of the Treatise on Painting continuing the analysis of leaf light. It finishes a demonstration of a half-shaded, half-transparent leaf (letters p, o with light m and eye n), then explains ([894]) that among leaves between light and eye the nearest is darkest and the most remote lightest. Further chapters observe ([895]) that young plants, above all the walnut, have more transparent leaves and cleaner bark and are brighter in May than September, and that plant shadows are never black; and ([896]) that leaves against the air take on the air's colour while their transparent reverse glows a beautiful yellow-green. A small pen drawing of a leaf cluster sits in the middle of the page.
On this page
A leaf half shaded, half transparent (p, o, m, n)
Let p, o be the leaf, m the light and n the eye: the eye sees o shaded, because the light strikes it at unequal angles neither on the face nor the reverse, while p is lit on the face and that light shows through on its reverse. So a single leaf can read as partly shadowed and partly transparent at once.
Dark leaves in front of transparent ones [894]
When leaves are set between the light and the eye, the leaf nearest the eye is the darker and the most remote the lighter, since the remote one is not seen against the air. This happens with leaves lying from the centre of the tree outward, toward the light.
Young plants and the greens of May [895]
Young plants, and above all the walnut, have more transparent leaves and cleaner bark than old ones, and are brighter in May than in September. The shadows of plants are never wholly black, because where the air penetrates there can be no darkness.
The colour of leaves against the air (a, b, c) [896]
With the light from m and the eye at n, the eye sees the colour of leaves a, b all partaking of the colour of m, that is of the air; while b, c seen from the reverse show transparent, of a most beautiful green tending to yellow. A pen sketch of a leaf cluster in the page's centre accompanies these observations.