Galilei, Galileo, The systems of the world, 1661

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            <p type="main">
              <s>
                <pb xlink:href="065/01/071.jpg" pagenum="65"/>
              white, but not burniſhed; would this yet ſuffice to the making
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              of it viſible, and apt for darting forth the light of the Sun?</s>
            </p>
            <p type="main">
              <s>SALV. </s>
              <s>It would ſuffice in part; but would not give a light ſo
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              ſtrong, as it doth being mountainous, and in ſum, full of
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              eminencies and great cavities. </s>
              <s>But theſe Philoſophers will never
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              yield it to be leſſe polite than a glaſſe; but far more, if more it
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              can be imagined; for they eſteeming that to perfect bodies perfect
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              figures are moſt ſutable; it is neceſſary, that the ſphericity of thoſe
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              Cœleſtial Globes be moſt exact; beſides, that if they ſhould
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              grant me ſome inequality, though never ſo ſmall, I would not
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              ſcruple to take any other greater; for that ſuch perfection
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              ing in indiviſibles, an hair doth as much detract from its perfection
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              as a mountain.</s>
            </p>
            <p type="main">
              <s>SAGR. </s>
              <s>Here I meet with two difficulties, one is to know the
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              reaſon why the greater inequality of ſuperficies maketh the
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              ger reflection of light; the other is, why theſe
                <emph type="italics"/>
              Peripatetick
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              tlemen are for this exact figure.</s>
            </p>
            <p type="main">
              <s>SALV. </s>
              <s>I will anſwer to the firſt; and leave to
                <emph type="italics"/>
              Simplieius
                <emph.end type="italics"/>
              the
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                <arrow.to.target n="marg175"/>
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              care of making reply to the ſecond. </s>
              <s>You muſt know therefore,
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              that the ſame ſuperficies happen to be by the ſame light more or leſs
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              illuminated, according as the rayes of illumination fall upon them
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                <arrow.to.target n="marg176"/>
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              more or leſſe obliquely; ſo that the greateſt illumination is where
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              the rayes are perpendicular. </s>
              <s>And ſee, how I will prove it to your
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              ſenſe. </s>
              <s>I bend this paper, ſo, that one part of it makes an angle
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              upon the other: and expoſing both theſe parts to the reflection of
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              the light of that oppoſite Wall, you ſee how this ſide which
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              ceiveth the rayes obliquely, is leſſe ſhining than this other, where
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              the reflection fals at right angles; and obſerve, that as I by
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              degrees receive the illumination more obliquely, it groweth
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              weaker.</s>
            </p>
            <p type="margin">
              <s>
                <margin.target id="marg175"/>
                <emph type="italics"/>
              The more rough
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              ſuperficies make
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              greater reflection
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              of light, than the
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              leſs rough.
                <emph.end type="italics"/>
              </s>
            </p>
            <p type="margin">
              <s>
                <margin.target id="marg176"/>
                <emph type="italics"/>
              Perpendicular
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              rays illuminate
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              more than the
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              lique, and why.
                <emph.end type="italics"/>
              </s>
            </p>
            <p type="main">
              <s>SAGR. </s>
              <s>I ſee the effect, but comprehend not the cauſe.</s>
            </p>
            <p type="main">
              <s>SALV. </s>
              <s>If you thought upon it but a minute of an hour, you
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              would find it; but that I may not waſte the time, ſee a kind of
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              demonſtration thereof in
                <emph type="italics"/>
              Fig.
                <emph.end type="italics"/>
              7.</s>
            </p>
            <p type="main">
              <s>SAGR. </s>
              <s>The bare ſight of this Figure hath fully ſatisfied me,
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              therefore proceed.</s>
            </p>
            <p type="main">
              <s>SIMPL. </s>
              <s>Pray you let me hear you out, for I am not of ſo
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              quick an apprehenſion.</s>
            </p>
            <p type="main">
              <s>SALV. </s>
              <s>Fancie to your ſelf, that all the paralel lines, which you
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              ſee to depart from the terms A. B. are the rays which fall upon the
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                <arrow.to.target n="marg177"/>
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              line C. D. at right angles: then incline the ſaid C. D. till it hang
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              as D. O. now do not you ſee that a great part of thoſe rays which
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              peirce C. D. paſs by without touching D. O? </s>
              <s>If therefore D. O.
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              be illuminated by fewer rays, it is very reaſonable, that the light
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              received by it be more weak. </s>
              <s>Let us return now to the Moon, </s>
            </p>
          </chap>
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