ABSTRACT
Nicholas Copernicus was born in 1473 at Torun, in the kingdom of Poland. Although officially registered at Bologna as a student in canon law, and later in civil law, Copernicus seems already to have preferred astronomy. For ancient and medieval scholars, trigonometry and practical astronomy were merely branches of mathematics, and therefore had no deep metaphysical or ontological significance. The principal characteristics of Copernicus’s cosmological system are found in the famous seven postulates of the Commentanolus. Copernicus also breaks with the principle of plenitude with regard to the planetary spheres. Copernicus’s astronomy offered two great advantages. First, it eliminated Ptolemy’s large epicycle, replacing it with the orb of the earth’s motion. Second, it gave the inferior planets and the superior planets the same cosmological status, thus eliminating the need to reverse the role of the deferent and the epicycle to reproduce the different behaviors of the inferior planets and the superior planets.
