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._ XXV. _MADAM,_