In the midst of all dwells the sun.

At rest, however, in the middle of everything is the sun.

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

For a traveler going from any place toward the north, that pole of the daily rotation gradually climbs higher, while the opposite pole drops down an equal amount.

In first place we must observe that the universe is spherical. This is either because that figure is the most perfect, as not being articulated, but whole and complete in itself; or because it is the most capacious and therefore best suited for that which is to contain and preserve all things.

Accordingly, since nothing prevents the earth from moving, I suggest that we should now consider also whether several motions suit it, so that it can be regarded as one of the planets. For, it is not the center of all the revolutions.

More stars in the north are seen not to set, while in the south certain stars are no longer seen to rise.