The book describes a fascinating encounter between astrology and magic, exposing how Hermetic magic seeped into Jewish literature and Jewish philosophy. Following astral magic in its convoluted course, this original work sheds new light on rationalist Jewish thought in the Middle Ages. Having attained its authority mostly from its use in medical practice, astral magic also developed a theology and provided a key to biblical interpretation. Judah Halevi, Nahmanides, and others explained the meaning and influence of the commandments according to magic-astral models and techniques, generating a new perspective within medieval Jewish philosophy. The book is intended for scholars of philosophy, Jewish thought, astrology and magic, as well as for the general public with an interest in these areas.