[reflected light] and transparency.
OF THE VISIBILITY OF THESE ACCIDENTS.
These accidents of colour in the foliage of trees become confused at a great distance and that which has most breadth [whether light or shade, &c.] will be most conspicuous.
The proportions of light and shade in a leaf (423-426).
423.
OF THE SHADOWS OF A LEAF.
Sometimes a leaf has three accidents [of light] that is: shade, lustre [reflected light] and transparency [transmitted light]. Thus, if the light were at n as regards the leaf s, and the eye at m, it would see a in full light, b in shadow and c transparent.
424.
A leaf with a concave surface seen from the under side and up-side-down will sometimes show itself as half in shade, and half transparent. Thus, if o p is the leaf and the light m and the eye n, this will see o in shadow