Page 426 - Western Civilization A Brief History, Volume I To 1715 9th - Jackson J. Spielvogel

Medieval Conception of the Universe.
As this sixteenth-century illustration shows, the medieval cosmological view placed the earth at the center of the universe, surrounded by a series of concentric spheres. The earth was imperfect and constantly changing, whereas the heavenly bodies that surrounded it were perfect and incorruptible. Beyond the tenth and final sphere was Heaven, where God and all the saved souls were located. (The circles read, from the center outward: 1. Moon, 2. Mercury, 3. Venus, 4. Sun, 5. Mars, 6. Jupiter, 7. Saturn, 8. Firmament (of the Stars), 9. Crystalline Sphere, 10. Prime Mover; and around the outside, Empyrean Heaven—Home of God and All the Elect, that is, saved souls.)
studied mathematics and astronomy first at Krakow in his native Poland and later at the Italian universities of Bologna and Padua, published his famous book On the Revolutions of the Heavenly Spheres. Copernicus was not an accomplished observational astronomer and relied for his data on the records of his predecessors. But he was a mathematician who felt that Ptolemy’s geocentric system was too complicated and failed to accord with the observed motions of the heavenly bodies (see the box on p. 390). Copernicus hoped that his heliocentric (sun-centered) conception would offer a more accurate explanation.
Copernicus argued that the universe consisted of eight spheres with the sun motionless at the center and the sphere of the fixed stars at rest in the eighth sphere. The planets revolved around the sun in the order of Mercury, Venus, the earth, Mars, Jupiter, and Saturn. The moon, however, revolved around the earth. Moreover, according to Copernicus, what appeared to be the movement of the sun and the fixed stars around the earth was really explained by the daily rotation of
the earth on its axis and the journey of the earth around the sun each year.
The heliocentric theory had little immediate impact; most people were not yet ready to accept Copernicus’s thinking. But doubts about the Ptole- maic system were growing. The German scientist Johannes Kepler took the next step in destroying the geocentric conception and supporting the Copernican system.
Kepler
The work of Johannes Kepler (1571–1630) illustrates the narrow line that often separated magic and science in the early Scientific Revolution. An avid astrologer, Kepler possessed a keen interest in Hermetic thought and mathematical magic. In a book written in 1596, he elaborated on his theory that the universe was con- structed on the basis of geometric figures, such as the pyramid and the cube. Believing that the harmony of the human soul (a divine attribute) was mirrored in
388 Chapter 16 Toward a New Heaven and a New Earth: The Scientific Revolution
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