This book argues that from Constantine onwards there was an attempt to develop a form of Christian biographical writing which presented the life of certain individuals in such a way as to make them authoritative models for other Christians to follow. These Lives – whether of the Emperor Constantine as presented by Eusebius of Caesarea, Antony as presented by Athanasius, or the subjects of Lives written by Jerome in Latin and the Cappadocians in Greek – are to be distinguished both from the pagan Lives with which they have often been compared, and from the broader genre of hagiography. They sought to present their subjects as a new type of Christian hero, and to write what they hoped would be conversion texts. Such texts however fell victim in part to the very success of ‘the ascetic indicative’ (Williams's term): the excesses to which some ascetics went in their aspiration to holiness gradually became a cause for concern, and the fifth-century writer Theodoret felt it necessary to defend St Symeon the Stylite against potential detractors. Meanwhile Eusebius' confidence that the reign of Constantine signalled the arrival of a Christian empire now seemed less well-founded, and in the City of God, Augustine argued that authority could come only from Scripture; there could be no other guarantee. Williams is a sure guide to these central texts, and he is surely right to focus on them. But I suspect that the later Christian writers who none the less continued to write Christian Lives in such numbers had not read their Augustine.