The thesis comprises, in roughly equal proportions, a commentary on the first book of Heliodoros Aithiopika (a Greek novel of the third or fourth century A.D.); and prolegomena which treat issues raised by the work as a whole. A literal translation of Aithiopika I is included as an appendix. In the commentary a range of points is covered, including philological and textual points, and questions of literary interpretation, and of the historical background of the action of the novel. Some of the literary points relate to the whole corpus of extant ancient Greek novels. One particularly obscure historical point, the identity of the 'Boukoloi', is given extended consideration. The prolegomena consists of five chapters. The first is a brief survey of the textual tradition of the work. The second examines the question of its date of composition and of the identity of its author, surveying the history of this debate, and showing how the evidence of vocabulary can be used to add weight to the argument in favour of accepting the fourth century date (rather than the third century date favoured by some scholars), and the view that Heliodoros was a Christian. The third chapter disputes the current view that the use of terms for divine agencies in the text reflects a lack of a systematic theology. The fourth chapter asks whether the text bears any traces of the local cult of the author's home town of Emesa, and answers with a tentative affirmative. In the fifth chapter the author considers how his contributions to our understanding of the historical and conceptual background of the text could affect our interpretation of it as a literary work.