This book is an authoritative work tracing the development of mystical thought within the formative period of both traditions and will appeal not only to the scholar but to the general reader as well as a vital contribution to the interfaith understanding so necessary in our modern world. The author, formerly Spalding Professor of Eastern Religions and Ethics at the University of Oxford, discusses each of the two streams of mysticism in depth, and also draws illuminating comparisons between them by constant cross-reference. His discussion of Hindu mysticism concentrates on the classical Upanishads, the Yogasutras, the Bhagavad Gita and their commentaries. His absorbing study of the Islamic tradition includes the monistic revolution introduced by Abu Yazid, which the author traces to the influence of Indian thought, and the later writings of Ghazali.