Christopher Kelly is Professor of Classics and Ancient History at the University of Cambridge and President of Corpus Christi College. His books include Ruling the Later Roman Empire (2004), The End of Empire: Attila the Hun and the Fall of Rome (2009) and Theodosius II: Rethinking the Roman Empire in Late Antiquity (Cambridge, 2013). He is editor of the Journal of Roman Studies. He owes a great deal of his fascination with power and the workings of institutions to Keith Hopkins who supervised his doctoral thesis on 'Bureaucracy and corruption in the Later Roman Empire'.