Perhaps there will be prattlers who, although completely ignorant of mathematics, nevertheless take it upon themselves to pass judgment on mathematical questions, and on account of some passage in Scripture, badly distorted to their purpose, will dare to censure and assail what I have presented here.

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.

Of all things visible, the highest is the heaven of the fixed stars.

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

The scorn which I had reason to fear on account of the novelty and unconventionality of my opinion almost induced me to abandon completely the work which I had undertaken. . . . Astronomy is written for astronomers. To them my work too will seem, unless I am mistaken, to make some contribution.

Astronomy is written for astronomers

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.