Page:The Gradual Acceptance of the Copernican Theory of the Universe.djvu/133

 servant; therefore it is more probable that the heavens are moved and the earth is at rest than that the reverse is true.

Thirdly; no probable argument can be thought out from philosophy to prove that the earth is moved and the heavens are at rest. Nor can it be done by mathematics. By saying that the heavens are moved and the earth is at rest, all phenomena of the heavenly bodies can be solved. Just as in the same way in optics all can be solved by saying either that sight comes from the thing to the eye, or that rays go from the eye to the thing seen; so is it in astronomy. Therefore one ought rather to abide in the ancient and general opinion than in one received recently without justification.

Fourthly; the earth is the center of the universe; all the heavenly bodies are observed to be moved around it; therefore it itself ought to be motionless, for anything that moves, it seems, should move around or above something that is motionless.

Fifthly; if the earth is moved in a circle, either it moves that way naturally or by force, either by its own nature or by the nature of another. It is not by its own nature, for straight motion from above downward is natural to it; therefore circular motion could not be natural to it. Further, the earth is a simple body; and a simple body can not have two natural motions of distinct kinds or classes. Nor is it moved by another body; for by what is it moved? One has to say it is moved either by the sun or by some other celestial body; and this cannot be said, since either the sun or that body is said to be at rest or in motion. If it is said to be at rest, then it cannot impart movement to another. If it is said to be in motion, then it can not move the earth, because it ought to move either by a motion similar to its own or the opposite of it. It is not similar, since thus it would be observed to move neutrally as when two boats moving in the same direction, appear not to move but to be at rest. It is not the opposite motion, since nothing could give motion contrary to its own. And because Galileo seems to say, in so far as I have learned from your lordships, that the earth was moved by the sun; I prove anyway that this is not true since the movement of the sun and of the earth ought to be from contrary and, distinct poles. The sun, however, can not be the cause of the other's movement because it is moved above different poles. Lastly, the earth follows the motion of no other celestial body; since if it is moved, it moves in 24 hours, and all the other celestial bodies require the space of many days, months and years. Ergo. Finally, if the earth is moved by another, its motion would be violent; but this is absurd, for no violence can be regular and perpetual. 125