Archimedes Texts

SALV. I am ready to serve you. You have already seen me
draw the form of 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 difference, 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, it were one while above, & another while below the same,
receding and approaching to us so much as the Diameter of the cir
cle 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 big
ger than when it is above the Sun, near to its other conjunction; yet
neverthelesse, the difference is almost imperceptible Let us add an

other 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. 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, he maketh no mention at all;

and much less of Mars than was needful; I believe as being una
ble 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, 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 ob
served them, not having been able for all that to salve them, have
yet notwithstanding by other admirable occurrences been induced