The Heresy of Jacob Frank: From Jewish Messianism to Esoteric Myth is the first monograph on the religious philosophy of Jacob Frank (1726-1791), who, in the wake of the false messiah Sabbetai Zevi, led the largest mass apostasy in Jewish history. Based on close readings of Frank's late teachings, recorded in 1784 and 1790, The Heresy of Jacob Frank presents Frank as an original and prescient figure at the crossroads of tradition and modernity, reason and magic. Frank's worldview combines an antinomian, skeptical rejection of religious law with a supernatural, Western Esotericist myth of immortal beings, magic, and worldly power. Frank's goal was alchemical in nature, culminating in physical transformation, power, and immortality, and his messiah was a syncretic female figure known as the Maiden, whose characteristics draw on Kabbalah, magic, and the veneration of the Black Virgin of Częstochowa, where Frank was imprisoned for twelve years. Sexual ritual, apparently tightly limited and controlled by the sect, was not a libertine bacchanal but a transgressive enactment of the messianic reality, a corporealization of what would later become known as spirituality. While Frank was undoubtedly a manipulative, even abusive leader whose sect mostly disappeared from history, his ideology anticipated themes that would become predominant in the Haskalah, early Hasidism, and even contemporary "New Age" Judaism. And his unbelievable, winding journey from Sabbatean heretic to eighteenth-century charlatan- alchemist-spy is perhaps even more remarkable than the radical theology he preached.