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

Those things which I am saying now may be obscure, yet they will be made clearer in their proper place.

For it is the duty of an astronomer to compose the history of the celestial motions through careful and expert study.

Therefore I would not have it unknown to Your Holiness, the the only thing which induced me to look for another way of reckoning the movements of the heavenly bodies was that I knew that mathematicians by no means agree in their investigation thereof.

The strongest affection and utmost zeal should, I think, promote the studies concerned with the most beautiful objects, most deserving to be known.

So far as hypotheses are concerned, let no one expect anything certain from astronomy, which cannot furnish it, lest he accept as the truth ideas conceived for another purpose, and depart from this study a greater fool than when he entered it.

Pouring forth its seas everywhere, then, the ocean envelops the earth and fills its deeper chasms.