After completing his undergraduate degree in Indian Studies at the University of Cambridge, Toby Mayer went on to study Medieval Arabic Thought at the University of Oxford, where he did his doctoral thesis on Ibn Sina's Book of Allusions (al-Isharat) and its commentaries. He has taught courses on medieval Muslim philosophy, scriptural hermeneutics and Sufi mysticism at the School of Oriental and African Studies (SOAS), University of London, and at the Institute of Ismaili Studies. Central to his research interests is the later, Isma'ili-influenced, thought of Muhammad b. 'Abd al-Karim al-Shahrastani (d. 1153), and the reception of Avicennism. Professor Ian Richard Netton is a specialist in medieval Islamic Philosophy, Comparative Religion, and Anthropology of Religion with a particular interest in ritual. After teaching and researching at the University of Exeter for many years, he was appointed the University of Leeds' first Professor of Arabic Studies in 1995 where he also served as Director of the then Centre for Medieval Studies. In 2007 he returned to the University of Exeter where he is Professor of Islamic Studies. He is the author or editor of 22 other books and numerous articles as well as being the Series Editor for three major series: the Routledge Culture and Civilisation in the Middle East Series, the Routledge Sufi Series, and the Edinburgh History of the Islamic Empires Series. Samer Traboulsi is Associate Professor of History of the Middle East and the Muslim World at the University of North Carolina at Asheville. He received his PhD in Near Eastern Studies from Princeton University in 2005. He is mainly interested in the formation and development of religious groups in the Muslim World and has published a book and a number of articles on the Isma'ilis in Yemen, the rise of the Wahhabi movement, and the history of Saudi Arabia.