Answer to Maestro Andrea da Imola, who said that the solar rays
reflected from a convex mirror are mingled and lost at a short
distance; whereby it is altogether denied that the luminous side of
the moon is of the nature of a mirror, and that consequently the
light is not produced by the innumerable multitude of the waves of
that sea, which I declared to be the portion of the moon which is
illuminated by the solar rays.

Let _o p_ be the body of the sun, _c n s_ the moon, and _b_ the eye
which, above the base _c n_ of the cathetus _c n m_, sees the body
of the sun reflected at equal angles _c n_; and the same again on
moving the eye from _b_ to _a_. [Footnote: The large diagram on the
margin of page 161 belongs to this chapter.]

Explanation of the lumen cinereum in the moon.