If the light comes from _m_ and the eye is at _n_ the eye will see
the colour of the leaves _a b_ all affected by the colour of _m_
--that is of the atmosphere; and _b c_ will be seen from the under
side as transparent, with a beautiful green colour verging on
yellow.

If _m_ is the luminous body lighting up the leaf _s_ all the eyes
that see the under side of this leaf will see it of a beautiful
light green, being transparent.

In very many cases the positions of the leaves will be without
shadow [or in full light], and their under side will be transparent
and the right side lustrous [reflecting light].