Nicolaus Copernicus published the Revolutions of the Heavenly Spheres in 1543. In Book I, Copernicus presents his heliocentric model of the universe. He argues that the Sun, not the Earth, is the center of the universe. He also correctly determined the order of the planets. He wrote that the planets revolve around the Sun in the following spheres – Mercury, Venus, Earth, Mars, Jupiter, and Saturn. However, he stubbornly held onto the belief that the planets must revolve around the sun in perfect circles; for God is perfect. This caused him to mistakenly retain Ptolemy’s system of epicycles to explain the motions of the heavens.
“Among the many various literary and artistic pursuits which invigorate men’s minds, the strongest affection and utmost zeal should, I think, promote the studies concerned with the most beautiful objects, most deserving to be known. This is the nature of the discipline which deals with the universe’s divine revolutions, the asters’ motions, sizes, distances, risings and settings, as well as the causes of the other phenomena in the sky, and which, in short, explains its whole appearance. What indeed is more beautiful than heaven, which of course contains all things of beauty? This is proclaimed by its very names (in Latin), caelum and mundus, the latter denoting purity and ornament, the former a carving. On account of heaven’s transcendent perfection most philosophers have called it a visible god.”
“Whoever denies its necessity for the teacher of any branch of higher learning is thinking foolishly, according to Plato. In his opinion it is highly unlikely that anyone lacking the requisite knowledge of the sun, moon, and other heavenly bodies can become and be called godlike.”
“At rest, however, in the middle of everything is the sun. For in this most beautiful temple, who would place this lamp in another or better position than that from which it can light up the whole thing at the same time? For, the sun is not inappropriately called by some people the lantern of the universe, its mind by others, and its ruler by still others. (Hermes) the Thrice Greatest labels it a visible god, and Sophocles’ Electra, the all-seeing. Thus indeed, as though seated on a royal throne, the sun governs the family of planets revolving around it.”