The worldly culture of northern Europe in the two centuries between the end of the Carolingian Empire and the "renaissance of the twelfth century" is, in the words of Claudio Leonardi, an "age without a name." The difficulty of naming the period might be a lack of coherence among its parts and, at the same time, a lack of conceptual apparatus for formulating a synthesis. C. Stephen Jaeger argues that such a synthesis of culture from 950...