Salusbury, Thomas, Mathematical collections and translations (Tome I), 1667

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              <s>
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              illuminated parts of the Terreſtrial ſuperficies appear beheld from
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              the Moon, depends not on this alone, but on the divers aſpects
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              which the Moon is ſtill changing with the Sun; ſo that, if for
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              ſtance, the Moon punctually followed the motion of the Sun, and
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              ſtood, for example, always in a direct line between it and the
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              Earth, in that aſpect which we call Conjunction, it looking always
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              to the ſame Hemiſphere of the Earth which the Sun looks unto,
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              ſhe would behold the ſame all light: as on the contrary, if it ſhould
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              always ſtay in Oppoſition to the Sun, it would never behold the
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              Earth, of which the dark part would be continually turn'd towards
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              the Moon, and therefore inviſible. </s>
              <s>But when the Moon is in
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              Quadrature of the Sun, that half of the Terreſtrial Hemiſphere
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              poſed to the ſight of the Moon which is towards the Sun, is
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              nous; and the other towards the contrary is obſcure: and
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              fore the illuminated part of the Earth would repreſent it ſelf to the
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              Moon in a ſemi-circular figure.</s>
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              <s>SAGR. </s>
              <s>I clearly perceive all this, and underſtand very well,
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              that the Moon departing from its Oppoſition to the Sun, where it
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              ſaw no part of the illumination of the Terreſtrial ſuperficies, and
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              approaching day by day nearer the Sun, ſhe begins by little and
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              little to diſcover ſome part of the face of the illuminated Earth;
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              and that which appeareth of it ſhall reſemble a thin ſickle, in regard
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              the figure of the Earth is round: and the Moon thus acquiring by
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              its motion day by day greater proximity to the Sun, ſucceſſively
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              diſcovers more and more of the Terreſtrial Hemiſphere enlightned,
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              ſo that at the Quadrature there is juſt half of it viſible, inſomuch
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              that we may ſee the other part of her: continuing next to proceed
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              towards the Conjunction, it ſucceſſively diſcovers more and more
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              of its ſurface to be illuminated, and in fine, at the time of
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              ction ſeeth the whole Hemiſphere enlightned. </s>
              <s>And in ſhort, I
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              very well conceive, that what befalls the Inhabitants of the Earth,
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              in beholding the changes of the Moon, would happen to him that
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              from the Moon ſhould obſerve the Earth; but in a contrary order,
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              namely, that when the Moon is to us at her full, and in Oppoſition
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              to the Sun, then the Earth would be in Conjunction with the Sun,
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              and wholly obſcure and inviſible; on the contrary, that poſition
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              which is to us a Conjunction of the Moon with the Sun, and for
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              that cauſe a
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              M
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              oon ſilent and unſeen, would be there an Oppoſition
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              of the Earth to the Sun, and, to ſo ſpeak,
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              Full Earth,
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              to wit, all
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              enlightned. </s>
              <s>And laſtly, look what part of the Lunar ſurface
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              pears to us from time to time illuminated, ſo much of the Earth
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              in the ſame time ſhall you behold from the Moon to be obſcured:
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              and look how much of the Moon is to us deprived of light, ſo much
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              of the Earth is to the Moon illuminated. </s>
              <s>In one thing yet theſe
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              mutual operations in my judgment ſeem to differ, and it is, that it </s>
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          </chap>
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