Post Lot Text
First edition of Kepler's major cosmological treatise, an exposition of his theory of the harmony of the universe, containing the third law of planetary motion. He related the magnitude of the planetary orbits to their periods of revolution around the sun: "the squares of the periods of the planets round the sun are proportional to the cubes of the distances". Kepler's laws form the necessary bridge between Galileo and Newton's concept of universal gravitation. "Harmony of the Universe" also contains important contributions to geometry and musical theory. Despite some inevitable browning because of the quality of German paper at this period, this is a fine copy in contemporary vellum.