The word ‘sufi’ evokes timeless images of whirling dervishes and an ancient but equally timeless lore of spirituality with only the most tenuous links to Islam. Thankfully, there is now a substantial scholarly literature which shows that sufi thought and practice also has a history, and that this history is inextricably connected with the history of Islamic piety at large. As the etymology of the word ‘sufi’ (wearer of wool) reminds us, the early sufis had emerged out of the ranks of Muslim renunciants in Baghdad between the late eighth and early tenth centuries. What distinguished this group from ordinary renunciants was their inward turn, their search for a more intimate knowledge of God through a variety of techniques of self-transformation. Initially a relatively marginal group, sufis had succeeded by the eleventh century in spreading across a vast Islamic world, and, notwithstanding the controversies surrounding some sufi beliefs and practices, normative sufism had become largely accepted as a legitimate part of what had by then been established as Sunni Islam.1