Daniel H. Nexon is an assistant professor in both the Department of Government and the School of Foreign Service at Georgetown University. His current work concerns grand strategy and the varieties of power-political competition, with a focus on the relations between great powers and their weaker allies and clients. Dr. Nexon received a BA from Harvard University and an MA and PhD from Columbia University. His most recent articles have explored the dynamics of empires and their relevance, or lack thereof, for contemporary U.S. foreign policy. He is the author of a forthcoming book, tentatively titled Religious Conflict, International Change, and the Struggle for Power in Early Modern Europe (Princeton University Press, 2009). He has held prior fellowships at the Center for International Security and Cooperation at Stanford University and the Mershon Center for International Security Studies at Ohio State University. He is, entirely by default, one of the world’s leading authorities on the nexus between Harry Potter and international relations.