This book is a version of a doctoral thesis written at Trinity College, Cambridge, with the help of generous funding from the British Academy. It has benefited from the comments and contributions of many scholars, chief amongst them my supervisor Philip Hardie, my debt to whom will be evident from every page. Neil Hopkinson and Richard Hunter were kind enough to read sections of the thesis, and its examiners, Michael Reeve and Don Fowler, have consistently given me firm advice and firm encouragement. The thesis was completed during the first year of an Assistant Lectureship at University College Dublin, and the book during the first year of a Teaching Fellowship at Brasenose College, Oxford, and I owe a particular debt of thanks for the warmth of their welcome to the Department of Classics at UCD, especially Theresa Urbainczyk and Andrew Erskine, to the members of the Classics Department at Trinity College, Dublin, especially Kathleen Coleman, and the Fellows and students of BNC, the latter perhaps the most welcoming of all. Bill Lavelle, Jon Hesk and Peter Stewart have been rich and enthusiastic sources of ideas and information. The book is dedicated to Andrea Swinton, without whom it would never have been written at all, and to my father.