This study treats the religious and intellectual history of the city of Harran (Eastern Turkey) from biblical times down to the establishment of Islam. The author starts from the well-known reference in the Q'uran and the early Islamic histories to the people of Harran as Sabians, one of the peoples of the book . He unravels strands of religious tradition in Harran that run from the old Semitic planetary cults through Hellenistic hermeticism, gnosticism and Neo-Pythagoreanism and Christian cults to esoteric Islamic sects such as the Sufis and Shia.