This book had its origins in the W. B. Stanford Memorial Lectures at Trinity College, Dublin, in February 1996; I am extremely grateful to John Dillon and Kathy Coleman both for the honour of their invitation and for the warmth of their hospitality, then and thereafter. My audiences in Dublin were very generous and their various comments and questions most illuminating. In particular, Vasilis Politis and John Cleary made me clarify a good deal that had been unclear; whatever opacity there remains – and I fear there may be far too much – is despite their best efforts.

In a form close to the present one Chapter 2 was delivered at the Southern Association for Ancient Philosophy in September 1996, and again at Queen's University, Belfast; and it is published in Dialogos 1998. I am grateful to the editors for permission to reprint that material here. A French version of some of Chapters 5 and 6 was delivered at the Sorbonne in 1996, and is published as ‘Téléologie et Autonomie dans le Philèbe de Platon’ in La fêlure du plaisir et la pensée. Études sur le Philèbe de Platon vol. I, ed. M. Dixsaut. Some of the same material was delivered at University College Cork and at King's College London. On all these various occasions I was fortunate in my audiences, whom I should like warmly to thank. In addition John Dillon, Verity Harte, Alan Lacey and Vasilis Politis have all read and commented upon a draft of the whole book; I am extremely grateful to them, both for their patience and for their insights. As reader for the Press, John Cooper made extensive comments on the whole manuscript with his customary care and incisiveness.