This is very well researched and written introduction to the Islamic science of tassawuf which is the Arabic word usually translated as Sufism. The looks at the origins of Sufism, its historical development, its branching into various brotherhoods, its importance in Islamic history as well as the various aspect of Sufi methodology and worship. Most importantly, This bookputs Sufism where it belongs: at the heart of Islam and it shows the Sufism is not, as some have argued extraneous to the Islamic belief. In other words, though it has some similarities with other mystical aspect of other religions, it is totally a product of Islam and its orthodox teachings.