Augustine Casiday is Senior Lecturer in Historical Theology at the University of Wales, Trinity Saint David, Lampeter. He is author of Tradition and Theology in St John Cassian (2006) and The Trinity and Incarnate Word (2008). He is editor of The Orthodox Christian World (2012), co-editor with Andrew Louth of Byzantine Orthodoxies (2006) and with Frederick W. Norris, of The Cambridge History of Christianity, Volume II: Constantine to c.600 (Cambridge, 2007).