The last major event in Renaissance astronomy is the work of Nicolaus Copernicus (1473–1543). He was among the first generation of astronomers to be trained with the "Theoricae novae" and the "Epitome". Shortly before 1514 he began to revive Aristarchus's idea that the Earth revolves around the Sun. He spent the rest of his life attempting a mathematical proof of heliocentrism. When "De revolutionibus orbium coelestium" was finally published in 1543, Copernicus was on his deathbed. A comparison of his work with the "Almagest" shows that Copernicus was in many ways a Renaissance scientist rather than a revolutionary, because he followed Ptolemy's methods and even his order of presentation. In astronomy, the Renaissance of science can be said to have ended with the works of Johannes Kepler (1571–1630) and Galileo Galilei (1564–1642).