When I first read Augustine's Confessions I was intrigued by the prominence of the theme of friendship. As I explored the literature of the fourth and early fifth centuries it became clear to me that this was not unusual in the writings of the time. Thus I was led to the present investigation in which I aim to see how consistent is the picture of the nature and duties of friendship in a Christian context emerging from the letters, theological and ascetic writings of some of the leading patristic writers. This investigation also necessarily related the Christian ideas closely to the main Classical – Greek and Roman – theories on friendship developed in antiquity which generally formed the basis for the Christian theories and therefore offers further evidence for the relations of pagan and Christian at an important stage in the development of the early Church as it negotiated the move from pagan antiquity to Christian Middle Ages.

I am grateful to Andrew Louth not only for introducing me to the world of the Church Fathers, but for all his advice and guidance along the road which led to this book. I was also assisted by Steven Collins who read it through at an early stage, and by the comments of O. M. T. O'Donovan and P. G. Walsh. I am greatly indebted for practical support to my parents and parents-in-law, and to my friends Richard Ruther-ford, Emily Kearns and Nicholas Purcell for discussion and learned advice on so many occasions.