In the late Alan F. Segal is at his very best. This reissued and expanded edition—now containing his celebrated "Heavenly Ascent in Hellenistic Judaism, Early Christianity, and Their Environment"—delineates the variegated nature of both Judaism and Christianity in their formative periods. As Segal demonstrates, it is more accurate to speak of Judaisms and Christianities. Through his deft deployment of social-scientific methods and due attention to Jewish primary sources from the Second Temple period, Segal is able to trace the intricate, internecine struggles among Jewish, Christian, and gnostic communities in the earliest days of the Common Era. In doing so, Segal masterfully validates the importance of inductive historical reconstruction and analytical comparative study for illuminating the complex religious world of the first three centuries.