Winner of the Journal of the History of Ideas's Morris D. Forkosch prize This book traces the development thought about God and the relationship between God's being and activity from Aristotle, through the pagan Neoplatonists, to thinkers such as Augustine, Boethius, and Aquinas (in the West) and Dionysius the Areopagite, Maximus the Confessor, and Gregory Palamas (in the East). The resulst is a comparative history of philosophical thought in the two halves of Christendom, providing a philosophical backdrop to the schism between the Eastern and Western churches.