Paul E. Walker (Ph.D. University of Chicago, 1974) was director of the American Research Center in Egypt for over ten years (1976-86). He is currently Deputy Director for Academic Programs, Center for Middle Eastern Studies at the University of Chicago. As a specialist in the history of the Islamic thought, he has published over twelve books, among them Early Philosophical Shiism (Cambridge, 1993); Hamid al-Din al-Kirmani: Ismaili Thought in the Age of al-Hakim (London, 1999); The Advent of the Fatimids (with Wilferd Madelung; London, 2000); Exploring an Islamic Empire: Fatimid History and Its Sources (London, 2002); and Caliph of Cairo: al-Hakim bi-Amr Allah, 996-1021 (Cairo, 2009).


David Simonowitz is Assistant Professor of Middle East Studies at Pepperdine University in Malibu, California, having gained his PhD in Islamic Studies at the University of California, Los Angeles in 2004. He now specializes in the study of the history of Muslim communal practices that bridge language, text (in the broadest sense), and space, whether ritual, social, or discursive.

Ismail K. Poonawala is Professor of Arabic & Islamic Studies at the University of California, Los Angeles, where he has worked since 1974, after completing his PhD on Islamic Studies in 1968. He has also taught at McGill and Harvard universities. As well as contributing widely to various encyclopaedias, he was written many articles and books, including Biobibliography of Isma 'ili Literature (1977) and, more recently, a critical edition of al-Sijistani's Kitab al-Maqalid al-malakutiyya (2011).


Godefroid de Callatay is Professor of Arabic and Islamic Studies at the Oriental Institute of the University of Louvain. He has specialized in the history of Arabic sciences and philosophy, and the role played by Islam in the transmission of knowledge from Greek Antiquity to the Latin West during the Middle Ages. Amongst other subjects, he has published extensively on the Rasa'il Ikhwan al-Safa, and already contributed to the present series by editing, together with Bruno Halflants, the short version of the Epistle on Magic (52a). Since 2012, he also directs 'Speculum Arabicum', a project on comparative medieval encyclopaedism at the University of Louvain.