This book introduces Augustine of Hippo and his influence on Christian theology. Part One works through all thirteen books of the Confessions, introducing the life and thought of the bishop of Hippo with commentary on frequent but brief quotations. The Confessions reveal Augustine's major doctrinal concerns, some of them explicitly and thoroughly (such as the Manichees, Platonists, scripture), others implicitly (monasticism, Donatism, ministry), and some in passing (Trinity) or as a preview (Pelagians). Part Two sketches the medieval reception of the Augustinian theological legacy, not chronologically but topically, in the order of the concerns in the Confessions, such as original sin, St. Monica, medieval Manichees, monastic communities, new Donatists, Neo-Platonism, the introspective soul, symbolic scripture, the Trinity, and above all the recurring Pelagian controversies over free will and grace, election and predestination, that continued into the Reformation.