The earth together with its surrounding waters must in fact have such a shape as its shadow reveals, for it eclipses the moon with the arc of a perfect circle.

Therefore, in the course of the work I have followed this plan: I describe in the first book all the positions of the orbits together with the movements which I ascribe to the Earth, in order that this book might contain, as it were, the general scheme of the universe.

We regard it as a certainty that the earth, enclosed between poles, is bounded by a spherical surface.

I shall now recall to mind that the motion of the heavenly bodies is circular, since the motion appropriate to a sphere is rotation in a circle.

First of all, we must note that the universe is spherical.

The massive bulk of the earth does indeed shrink to insignificance in comparison with the size of the heavens.