Timothy David Barnes is Professor Emeritus of the University of Toronto. He is the author of Constantine and Eusebius (1981), The New Empire of Diocletian and Constantine (1982), Athanasius and Constantius: Theology and Politics in the Constantinian Empire (1993), Ammianus Marcellinus and the Representation of Historical Reality (1998), and Early Christian Hagiography and Roman History (2010).