'Ali Humayun Akhtar's Philosophers, Sufis, and Caliphs explores the interface and interplay between Sufism, philosophy, and politics in the medieval Islamic world. Examining diverse fields in the history of ideas - from metaphysics to politics, cosmology to psychology, and Sufism to philosophical theology - Akhtar examines how scholarly religious authority affected and was affected by political leadership between the tenth and twelfth centuries. The extensively researched chapters on the Spanish Sufi metaphysicians … are particularly valuable for placing their thought in the context of the dialectic of scholars with local monarchs and emirs.' Leonard Lewisohn, Institute of Arab and Islamic Studies, University of Exeter