That part of the trees will be seen to lie in the least dark shadow
which is farthest from the earth.
To prove it let _a p_ be the tree, _n b c_ the illuminated
hemisphere [the sky], the under portion of the tree faces the earth
_p c_, that is on the side _o_, and it faces a small part of the
hemisphere at _c d_. But the highest part of the convexity a faces
the greatest part of the hemisphere, that is _b c_. For this
reason--and because it does not face the darkness of the earth--it
is in fuller light. But if the tree has dense foliage, as the
laurel, arbutus, box or holm oak, it will be different; because,
although _a_ does not face the earth, it faces the dark [green] of
the leaves cut up by many shadows, and this darkness is reflected
onto the under sides of the leaves immediately above. Thus these
trees have their darkest shadows nearest to the middle of the tree.
437.