_MADAM,_
Having given you my opinion, both of the substance and perception
of Light, in my last Letter, I perceive your desire is to know how
_Shadows_ are made. Truly, _Madam_, to my sense and reason, it appears
most probable, that shadows are made by the way of patterning: As for
example; when a Man's, or Trees, or any other the like Creature's
shadow is made upon the Ground, or Wall, or the like; those bodies, as
the Ground, or Wall, do, in my opinion, pattern out the interposing
body that is between the light and them: And the reason that the
shadow is longer or shorter, or bigger or less, is according as the
light is nearer or further off; for when the light is perpendicular,
the interposing body cannot obscure the light, because the light
surrounding the interposing body by its brightness, rather obscures
the body, then the body the light; for the numerous and splendorous
patterns of light taken from the body of the Sun, do quite involve the
interposing body. Next, you desire to know, _Whether the light we see
in the Moon, be the Moons own natural light, or a borrowed light from
the Sun_: I answer, that in my opinion, it is a borrowed light; to
wit, that the Moon doth pattern out the light of the Sun: and the proof
of it is, that when the Sun is in an Eclipse, we do plainly perceive
that so much of the Sun is darkned as the Moon covers; for though those
parts of the Moon, that are next the Sun, may, for any thing we know,
pattern out the light of the Sun, yet the Moon is dark on that side
which is from the Sun. I will not say, but that part of the Moon which
is towards the Earth, may pattern out the Earth, or the shadow of the
Earth, which may make the Moon appear more dark and sullen; But when
the Moon is in an Eclipse, then it is plainly perceived that the Moon
patterns out the Earth, or the shadow of the Earth. Besides, those
parts of the Moon that are farthest from the Sun, are dark, as we may
observe when as the Moon is in the Wane, and enlightened when the Sun
is nearer. But I will leave this argument to observing Astrologers, and
rest,
Madam,
_Your faithful Friend_
_and Servant._