Book excerpt: In “And They Shall Be One Flesh”: On the Language of Mystical Union in Judaism, Adam Afterman offers an extensive study of mystical union and embodiment in Judaism. Afterman argues that Philo was the first to articulate the notion of unio mystica in Judaism and is the source of the henōsis mysticism in the later Neoplatonic tradition. The study provides a detailed analysis of the Jewish medieval trends that developed different forms of mystical union and mystical embodiment through the divine name and spirit. The book argues that the development of unitive mysticism in Judaism is the fruit of the creative synthesis of rabbinic Judaism and Hellenistic and Arab philosophy, and a natural outcome of the theological articulation of the idea of monotheism itself.