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G. Galilæus, his Systeme.
Salv.I am ready to serve you. You have already seen me draw the form of the Copernican Systeme;Mars makes an hot assault upon the Copernican Systeme. against the truth of which Mars himself, in the first place, makes an hot charge; who, in case it were true, that its distances from the earth should so much vary, as that from the least distance to the greatest, there were twice as much differences, as from the earth to the Sun; it would be necessary, that when it is nearest unto us, its discus would shew more than 60. times bigger than it seems, when it is farthest from us; nevertheless that diversity of apparent magnitude is not to be seen, nay in its opposition with the Sun, when its nearest to the Earth, it doth not shew so much as quadruple and quintuple in bigness, to what it is, when towards the conjunction it cometh to be occulted under the Suns rayes. Another and greater difficulty doth Venus exhibit; For if revolving about the Sun, as Copernicus affirmeth,The Phænomena of Venus appear contrary to the Systeme of Copernicus. it were one while above, & another while below the same, receding and approaching to us so much as the Diameter of the circle described would be, at such time as it should be below the Sun, and nearest to us, its discus would shew little less than 40 times bigger than when it is above the Sun, near to its other conjunction; yet neverthelesse,Another difficulty raised by Venus against Copernicus. the difference is almost imperceptible Let us add another difficulty, that in case the body of Venus be of it self dark, and onely shineth as the Moon, by the illumination of the Sun, which seemeth most reasonable; it would shew forked or horned at such time as it is under the Sun, as the Moon doth when she is in like manner near the Sun; an accident that is not to be discovered in her.Venus, according to Copernicus, either lucid in it self, or else of a transparent substance. Whereupon Copernicus affirmeth, that either she is light of her self, or else that her substance is of such a nature, that it can imbue the Solar light, and transmit the same through all its whole depth, so as to be able to appear to us alwayes shining; and in this manner Copernicus excuseth the not changing figure in Venus: but of her small variation of Magnitude,Copernicus speaketh nothing of the small variation of bigness in Venus and in Mars. he maketh no mention at all; and much less of Mars than was needful; I believe as being unable so well as he desired to salve a Phænomenon so contrary to his Hypothesis, and yet being convinced by so many other occurrences and reasons he maintained, and held the same Hypothesis to be true. Besides these things, to make the Planets, together with the Earth, to move above the Sun as the Centre of their conversions, and the Moon onely to break that order,The moon much disturbeth the order of the other Planets. and to have a motion by it self about the earth; and to make both her, the Earth, and the whole Elementary Sphere, to move all together about the Sun in a year, this seemeth to pervert the order of this Systeme, which rendreth it unlikely and false. These are those difficulties that make me wonder how Aristarchus and Copernicus, who must needs have observed them, not having been able for all that to salve them, have yet notwithstanding by other admirable occurrences been induced
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