This book makes accessible, to a wide audience, the thought of Evagrius and Gregory on the soul, in the context of ancient philosophy/theology and the Cappadocians generally. Corrigan argues that in these two figures we witness the birth of new forms of thought and of empirical science in a new key. Evagrius and Gregory are no mere receivers of a monolithic pagan and Christian tradition, but innovative, critical interpreters on the range and limits of cognitive psychology, the soul-body relation, reflexive self-knowledge, personal and human identity and the soul's practical relation to goodness in the context of human experience and divine self-disclosure. This book provides a critical evaluation of their thought on these major issues and argues that in Evagrius and Gregory we see the important integration of many different concerns that later Christian thought was not always able to balance including: mysticism, asceticism, cognitive science, philosophy, and theology.