Sage, scientist, and sorcerer, Hermes Trismegistus was the culture-hero of Hellenistic and Roman Egypt. A human (according to some) who had lived about the time of Moses, but now indisputably a god, he was credited with the authorship of numerous books on magic and the supernatural, alchemy, astrology, theology, and philosophy. Until the early seventeenth century, few doubted the attribution. Even when unmasked, Hermes remained a byword for the arcane. Historians of ancient philosophy have puzzled much over the origins of his mystical teachings; but this is the first investigation of the Hermetic milieu by a social historian.