In 50 brief chapters, originally delivered as public audiences to the faithful in St Peter's Square, Benedict XVI offers absorbing, perceptive, and often edifying sketches of some of Christianity's greatest thinkers and writers. The historical circumstances and theological ideas of each are explained. The book is divided in four parts: The Apostolic Fathers: Witnesses from the first generations after the New Testament; The Patristic Theologians: From councils and controversies, from Origen to Augustine; Early Medieval Thinkers: The beginnings of scholastic and monastic theologies; Later Medieval Thinkers: The flowering of Christian theology in the high Middle Ages. Benedict discusses the most notable theologians from East and West, along with figures whose primary witness was as ascetics, poets, mystics, and a number of popes, politicians, and missionaries. The historical circumstances and theological ideas of each is explained with the clarity of an experienced teacher. Benedict always has an eye to their deepest religious convictions and struggles as well as to their present importance to the church and Christian life today.