Sixthly; even so it is declared that the earth is moved. Nevertheless, it must be admitted to this that either the planets themselves or their spheres are moved, for in no other way can the diversities of aspects among themselves be solved; nor can a reason be given why the sun does not leave the Ecliptic and the moon does; and how a planet can be stationary or retrograde, high or low,—and many other phenomena. For this reason those who said the earth moved, as Bernardus Patricius and the others said, claimed that the primum mobile, forsooth, was stationary and that the earth was moved in its place; yet they could not in the least deny that the planets themselves were moved, but admitted it. That is the reason why both ancient and modern mathematicians, aside from the motion of the primum mobile, were forced to admit and consider the peculiar movements of the planets themselves. If therefore it must be acknowledged, and it is certain, that the stars and the celestial bodies are moved; then it is more probable that all movement perceived in the universe belongs rather to the heavenly bodies than to the earth. For if movement were ascribed to all the rest, why for that same reason is not diurnal rotation ascribed rather to the primum mobile than to the earth, particularly when our senses seem to decide thus? Although one may well be mistaken, sometimes, concerning other similar movements; yet it is not probable that all ages could be at fault, or should be, about the movements of its most important objects, of course the celestial luminaries.
Seventhly; it is proved by experience. For if the earth is moved, then an arrow shot straight up on high could never fall back to the place whence it was shot, but should fall somewhere many miles away. But this is not so. Ergo.
This can be answered and is so customarily in this way: this does not follow because the air is swept along with the earth, and so, since the air which carries the arrow is turning in the same way with the earth, the arrow also is borne along equally with it, and thus returns to the same spot. This in truth is a pure evasion and a worthless answer for many reasons.
It is falsely observed that the air is moved and by the same motion as the earth. For what should move the earth? Truly, if the air is moved by the same motion as the earth, either it ought to be moved by the earth itself, or by that other which moves the earth, or by itself. It is not moved by itself; since it has another motion, the straight one of course natural to itself, and also since it has a nature, an essence and qualities all different from the nature and the essence of the earth; therefore it could not by its own nature have the same motion as that other, but of necessity ought to have a different one.
