This book owes its development to a number of lectures and seminars, and the attendant discussion, given over the years at the Collège de France, the Sorbonne, the Ecole Pratique des Hautes Etudes, the Institut de Philosophie, the Centre National de la Recherche Scientifique, and King's College London. I would like to express my grateful thanks for these opportunities to Michel Tardieu, Monique Dixsaut, Philippe Hoffmann, Anca Vasiliu and Richard Sorabji (and David Papineau), as well as to my old friend and interlocutor Annick Charles-Saget. It also owes a great deal to the work and friendship of the late Jean Pépin, to whom I would like to pay tribute as having had an especially important place in my life. My wife, Miranda, has been particularly supportive of me and my work on this project: to her, grateful thanks.

My university, Bond University, has been generous in supporting this work and I would like to acknowledge this.

Lastly, my grateful thanks go to my patient and highly competent executive assistant, Anouschka Bridgman, for all her help with setting up the document, and to my research assistant Trishita Mathew.