The Universe, wrought for us by a supremely good and orderly Creator.

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.

Yet the widespread planetary theories, advanced by Ptolemy and most other astronomers, although consistent with the numerical data, seemed likewise to present no small difficulty. For these theories were not adequate unless they also conceived certain equalizing circles, which made the planet appear to move at all times with uniform velocity neither on its deferent sphere nor about its own epicycle's center.

Finally we shall place the Sun himself at the center of the Universe.

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

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.

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