Since that time, I have given my attention to observing these more accurately, urged on by a very distinguished man, Paul, Bishop of Fossombrone, who at that time had charge of the matter.

But what I may have accomplished herein I leave to the judgment of Your Holiness in particular, and to that of all other learned mathematicians; and lest I seem to Your Holiness to promise more regarding the usefulness of the work than I can perform, I now pass to the work itself.
[Footnote A: Nicolaus Copernicus was born in 1473 at Thorn in West Prussia, of a Polish father and a German mother.

He attended the university of Cracow and Bologna, lectured on astronomy and mathematics at Rome, and later studied medicine at Padua and canon law at Ferrara.

He was appointed canon of the cathedral of Frauenburg, and in this town he died in 1543, having devoted the latter part of his life largely to astronomy.
The book which was introduced by this dedication laid the foundations of modern astronomy.

At the time when it was written, the earth was believed by all to be the fixed centre of the universe; and although many of the arguments used by Copernicus were invalid and absurd, he was the first modern to put forth the heliocentric theory as "a better explanation." It remained for Kepler, Galileo, and Newton, to establish the theory on firm grounds.].