Evagrius of Pontus ( c .345-399 CE) has been renowned for his spiritual insight and psychological acumen ever since his lifetime, and despite his condemnation for heresy in the sixth century exercised a defining influence on the development of both Chalcedonian and non-Chalcedonian traditions. Rooting himself in scripture and patristic thought but also drawing widely upon pagan sources and making use of empirical observation, Evagrius constructed a comprehensive and unified theory of human origins, nature, destiny, and our place in a material cosmos understood as the sacramental self-revelation of a loving God who seeks by means of its beauty to awaken our desire for him. The state that Evagrius calls apatheia harmonises and stabilises the soul, establishing love as its disposition, and is rooted in the disciplines of the monastic life and a purified physical constitution. This book is the first full-length study of Evagrian apatheia and the most detailed examination to date of Evagrian anthropology. It situates them in their overall context of cosmology, salvation history, and the spiritual life. It describes a system which, while profoundly christocentric and deriving its structure from Paul, is a masterpiece of late antique philosophical synthesis incorporating elements of Platonic, Aristotelian, Stoic, and medical thought. It will be of interest to specialists in classical and late antique philosophy, to historians of philosophy, theology, spirituality, psychology, psychiatry, and medicine, to scholars of monasticism, and to theologians and philosophers interested in the human person.