This book is based on the Wilde Lectures in Natural and Comparative Religion, which I delivered at the University of Oxford in November and December 2002 under the title ‘Indic religions to 1200 AD: a critical and anthropological approach’. Those who were present at the lectures will realise that this book differs from the lectures in other respects besides the title. Most of the text of the lectures is here, in one form or another, but I have taken the opportunity to rethink and extend the argument in many places. Unfortunately, the extensive visual material presented in the lectures has had for practical reasons mostly to be excluded from the book.

This is a relatively short book, however, on a very large subject, and there has been no attempt to be comprehensive. The book focuses on the development of the yogic and Tantric tradition in Indic societies, and while I have discussed the wider context in which these events happened in considerable detail, I have not attempted to provide a comprehensive history of Indian religion.

It is difficult to deal with language transcription consistently and systematically in a book that ranges over several bodies of scholarly literatures with different conventions. The omission of diacritics is nevertheless a major irritant and often deprives the reader of vital information, quite apart from rendering it impossible to know how words might be pronounced. My general strategy has been to give only modern place names and words that are thoroughly Anglicised without diacritics.