Johannes Kepler's on the More Certain Fundamentals of Astrology Prague 1601

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. American Philosophical Society is collaborating with JSTOR to digitize, preserve and extend access to Proceedings of the American Philosophical Society. The traditional textbook in physics or astronomy views Johannes Kepler only with regard to his contributions to astronomy and, in particular, with regard to that limited portion of his astronomical works that has proved to be of continued utility: his three laws of planetary motion. If his astrological views are discussed at all, it is assumed that as an enlightened astronomer he believed astrology to be nonsense or at best a source of income forced on him by an unen-lightened patron. Such a view is not supported either by Kepler's writings or by the tradition of scientific astrology in which he worked. This tradition has roots that extend back to the earliest recorded scientific endeavors. In fact, Otto Neugebauer in his Exact Sciences in Antiquity makes a strong case for the claim that initially the fundamental doctrines of astrology were pure science. To a modern scientist, an ancient astrological treatise appears as mere nonsense. But we should not forget that we must evaluate such doctrines against the contemporary background. To Greek philosophers and astronomers the universe was a well defined structure of directly related bodies. The concept of predictable influence between these bodies is in principle not at all different from any modern mechanistic theory. And it stands in sharpest contrast to the ideas either of arbitrary rulership of deities or of the possibility of influencing events by magical operations. Compared with the background of religion, magic, and mysticism, the fundamental doctrines of astrology are pure science. Of course, the boundaries between rational science and loose speculation were rapidly obliterated and astrological lore did not stem-but rather promoted-superstition and magical practices.' This astrological boundary between rational science and loose speculation has been patrolled and defended by two outstanding astronomers: Claudius Ptolemy in the second century A.D., and Johannes Kepler in the seventeenth century A.D. Both these men see a purity in astronomy that does not exist in astrology, but the fundamentals of astrology, nevertheless, are defended as being well founded in …