Regiomontanus’s fame is today surpassed by that of his first notable successor, Nicolaus Copernicus, who wrote but one book and made but one important discovery. Neither in versatility nor in mathematical ability did Copernicus approach the genius of his predecessor, but he was assiduous in applying what he learned from Ptolemy and Regiomontanus, and brought forth not only a successor to the Almagest but the most famous single discovery, or theory, in the entire history of astronomy. He was in truth the only original astronomer and nearly the only competent astronomer of his age. He was born to a prosperous merchant family in Torun in Royal Prussia, according to his horoscope in 1473 on 19 February, Friday before the Throne of St. Peter (22 February), at 4:48 PM—that is, 0;12d or 1/5 day after noon, although the horoscope itself, analyzed in the Appendix, is for about 6:40 PM. Following the early death of his parents, he was raised in the household of his maternal uncle Lucas Watzenrode, a sour and gloomy man—no one, it was said, had ever seen him laugh—who in 1489 became Bishop of Warmia (Ermland), a small ecclesiastical state on the Baltic to the north, almost entirely surrounded by East Prussia under the rule of the Teutonic Order with a short border with Royal Prussia to the west. It was in Warmia that Copernicus was to spend most of his life. Uncle Lucas intended an ecclesiastical career for his nephew, and to that end Copernicus attended the University of Cracow from 1491 to 1495, but left without taking a degree.