Islamicists interested in Sufism have benefited from a growing number of worthwhile publications in recent years. Studies of South Asian Sufism in particular have broadened scholarly horizons by increasing the range of materials with which to reconstruct a complex history. One aspect of the history of Sufism that has been getting significant attention in various contexts lately is the role of authority in the person of the shaykh. Arthur Buehler offers in his study of South Asia's Naqshbandis something of a parallel to what Vincent Cornell has produced in his work on the role of the shaykh among North Africa's Shadhilis. He argues that Naqshbandi Sufism has witnessed an important shift in the role of the shaykh, from one of hands-on mystical tutelage to one of intercession. Buehler sets his chief argument in the context of evidence that major transformations occurred in the nature of Sufi spiritual authority beginning in the 9th through 11th centuries. In his first two chapters, Buehler lays out the general historical background. Before Sufism had been fully institutionalized into discrete orders, the “teaching shaykh” (shaykh at-ta⊂l―im) instructed all comers in the growing body of Sufi tradition. Imparting the wisdom of already legendary characters, they equipped their students with a working knowledge of the essentials of Sufism. They and their pupils were often quite mobile, and the teacher-student relationship remained relatively informal and distant. Beginning in the late 9th century, that relationship began to change. Over the next 200 years or so, a new kind of shaykh emerged as the normative type of Sufi authority. From a fixed abode, the “directing shaykh” (shaykh al-tarbiyya) provided increasingly proprietary instruction on the actual pursuit of the spiritual path to a select few disciples who pledged their sole allegiance to one spiritual guide. Now the shaykh imparted not merely generalized instructions on spiritual etiquette, but also soul-challenging advice and do-it-or-depart requirements for advancement on the mystical path. Regarded as virtually infallible, the directing shaykh initiated followers into a lineage, bestowed the khirqa, and generally exercised total authority over the disciple's daily affairs.