Patricia Crone is professor of Islamic history at the Institute for Advanced Study, Princeton. Her publications include Meccan Trade and the Rise of Islam (Princeton University Press, 1987 [reprinted 2004], God's Caliph: Religious Authority in the First Centuries of Islam (Cambridge University Press, 2003), and Medieval Islamic Political Thought (Edinburgh University Press, 2004; published in the United States as God's Rule: Government and Islam [Columbia University Press, 2004]).