Josef van Ess, Emeritus Professor of Islamic Studies and Semitic Languages, University of Tübingen, Germany, has published widely on the History of the Islamic World; Islamic theology and philosophy, especially with respect to the formative period (8th-10th centuries) and the age of the Mongol conquests (13th-14th centuries); and Islamic mysticism. His most famous work and is Theologie und Gesellschaft in 6 volumes (de Gruyter 1991-97), the first four volumes of which are now being published in English by Brill.