So, influenced by these advisors and this hope, I have at length allowed my friends to publish the work, as they had long besought me to do.

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.

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.

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

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

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

Therefore, having obtained the opportunity from these sources, I too began to consider the mobility of the earth.