Note 5 — BOOK I. THE GEOMETRICAL PERIOD

In his great book Copernicus says: “The movement of the heavenly bodies is uniform, circular, perpetual, or else composed of circular movements.” In this he proclaimed himself a follower of Pythagoras (see p. 14), as also when he says: “The world is spherical because the sphere is, of all figures, the most perfect” (Delambre, Ast. Mod. Hist., pp. 86, 87).