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

So if the worth of the arts were measured by the matter with which they deal, this art-which some call astronomy, others astrology, and many of the ancients the consummation of mathematics-would be by far the most outstanding. This art which is as it were the head of all the liberal arts and the one most worthy of a free man leans upon nearly all the other branches of mathe matics. Arithmetic, geometry, optics, geodesy, mechanics, and whatever others, all offer themselves in its service.

In the midst of all dwells the sun.

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

To know that we know what we know, and to know that we do not know what we do not know, that is true knowledge.

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

For what could be more beautiful than the heavens which contain all beautiful things.