A World Lit Only by Fire

by William Manchester

Johannes Kepler was one of the great Renaissance astronomers. The discoverer of the three principles of planetary motion, he provided the bridge from the ancient view of the skies to modern astronomy. His first publication after his appointment (in 1601) as imperial mathematician to the Holy Roman emperor’s court in Prague was De fundamentis astrologiae certioribus (The More Certain Basics of Astrology), in which he rejected the established view that the lives of men are determined celestially. Yet his astrological forecasts were regarded with awe. He cast the personal horoscopes of Emperor Rudolf II. Even so, in a world ruled by superstition, men of science were always suspect. In his late forties, when he was at the peak of his powers, Kepler learned that his mother had been indicted as a witch. He hurried to her side, not sparing his horses, inspired partly by filial duty, no doubt, but also to save his own skin. Indictment was usually followed by torture and the stake. Had his skillful intervention not saved her, he himself would have been a candidate for disgrace, the loss of office, and possibly even a trial before the Inquisition.