Recent historical research on the Scientific Revolution has focused on the contribution of ideas and practices that no longer belong to the realm of science, such as astrology and alchemy. For most of human history, interest in astronomy was inspired by the belief that the movement of heavenly bodies influenced events on earth. Many of the most celebrated astronomers were also astrologers. Used as a diagnostic tool in medicine, astrology formed a regular part of the curriculum of medical schools.

Centuries-old practices of magic and alchemy also remained important traditions for natural philosophers. Early modern practitioners of magic strove to understand and control hidden connections they perceived among different elements of the natural world, such as that between a magnet and iron. The idea that objects possessed hidden or “occult” qualities that allowed them to affect other objects was a particularly important legacy of the magical tradition. Belief in occult qualities — or numerology or cosmic harmony — was not antithetical to belief in God. On the contrary, adherents believed that only a divine creator could infuse the universe with such meaningful mystery.

Johannes Kepler exemplifies the interaction among these different strands of interest in the natural world. His duties as court mathematician included casting horoscopes for the royal family, and he based his own life on astrological principles. He also wrote at length on cosmic harmonies and explained elliptical motion through ideas about the beautiful music created by the combined motion of the planets. Kepler’s fictional account of travel to the moon, written partly to illustrate the idea of a non-earth-centered universe, caused controversy and may have contributed to the arrest and trial of his mother as a witch in 1620. Kepler also suffered because of his unorthodox brand of Lutheranism, which led to his condemnation by both Lutherans and Catholics.

Another example of the interweaving of ideas and beliefs is Sir Isaac Newton, who was both intensely religious and also fascinated by alchemy, whose practitioners believed (among other things) that base metals could be turned into gold. Critics complained that his idea of universal gravitation was merely a restatement of old magical ideas about the innate sympathies between bodies; Newton himself believed that the attraction of gravity resulted from God’s actions in the universe.