This article discusses the astronomical work of the Dutch humanist Albert van Leeuwen, or Albertus Leoninus (1543-1614). Leoninus came from a very prominent Utrecht family and took a doctorate in law from the university of Siena. However, during the Dutch Revolt, his family lost its position in government. Leoninus did not join any of the warring parties. Fleeing the troubles, he stayed several years in Germany, where he aligned himself with people of irenist and millenarist leanings. In 1578, Leoninus had a volume of astronornical writings printed at Cologne. Having travelled to Rome, he offered the book to the Pope as a contribution to the reform of the calendar. As his services were not called upon, he re-issued the book in 1583, this time with a dedicace to the (protestant) Utrecht town government. In this book, Leoninus made a very selective use of Copernicus' theories. He rejected the diurnal and annual motions of the earth and kept using the Ptolemaic punctum equans. However, he adopted Copernicus' theory of the moon, his theory of the motion of the solar apogee (which he adapted to a system with a fixed earth), and the Copernican theory of precession. As he saw it, the earth had a secular motion with respect to the fixed stars (Copernicus' third motion), whereby the poles on which the firmament was turning were defined by the position of the poles of the earth. His interest in precessional theory seems largely inspired by the fact that these secular motions were deemed to indicate the great epochs of world history and could be used for calculating the imminent end of the world.