When one green has another [green] behind it, the lustre on the
leaves and their transparent [lights] show more strongly than in
those which are [seen] against the brightness of the atmosphere.

And if the sun illuminates the leaves without their coming between
it and the eye and without the eye facing the sun, then the
reflected lights and the transparent lights are very strong.

It is very effective to show some branches which are low down and
dark and so set off the illuminated greens which are at some
distance from the dark greens seen below. That part is darkest which
is nearest to the eye or which is farthest from the luminous
atmosphere.