Janet Nelson, the distinguished British historian of the early Middle Ages, has said: "He took the study of medieval history into fields of cultural history and social history, social psychological history. He was interested in religion but not in an old-fashioned ecclesiastical history, institutional sort of way, but what made people think in this way: how did they conceptualise God? How did they think about religious symbols and rituals in the ways that they did? Why did these things change? That was his agenda. He wrote mostly about late antiquity, the very early period, but he sometimes ventured into the Middle Ages and whenever he did he transformed the scene. The great area he’s famous for doing is the cult of the saints."