J. Spencer Trimingham 
Sufi Orders in Islam [PDF ebook] 

Sufism, the name given to Islamic mysticism, has been the subject of many studies, but the orders through which the organizational aspect of the Sufi spirit was expressed has been neglected. The Sufi Orders in Islam is one of the earliest modern examinations of the historical development of Sufism and is considered a classic work in numerous sources of Islamic studies today. Here, author J. Spencer Trimingham offers a clear and detailed account of the formation and development of the Sufi schools and orders (tariqahs) from the second century of Islam until modern times. Trimingham focuses on the practical disciplines behind the mystical aspects of Sufism which initially attracted a Western audience. He shows how Sufism developed and changed, traces its relationship to the unfolding and spread of mystical ideas, and describes in sharp detail its rituals and ceremonial practices. Finally, he assesses the influence of these Sufi orders upon Islamic society in general. John O. Voll has added a new introduction to this classic text and provides readers with an updated list of further reading. The Sufi Orders in Islam will appeal not only to those already familiar with Triminghams groundbreaking research, but also to the growing reading public of Islamic studies and mysticism.