Finally we shall place the Sun himself at the center of the Universe. All this is suggested by the system of procession of events and the harmony of the whole Universe, if only we face the facts, as they say, "with eyes wide open."

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

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.

Mathematics is written for mathematicians.

Every light has its shadow, and every shadow hath a succeeding morning.

If there be some who, though ignorant of all mathematics . . . dare to reprove this work, because of some passage of Scripture, which they have miserably warped to their purpose, I regard them not, and even despise their rash judgement.