this volume and my forthcoming Reformation of the twelfth century are both concerned, though in different ways, with the changes in religious life and spirituality in the eleventh and twelfth centuries. Whereas the Reformation covers a broad spectrum of developments during a relatively short period, from about 1070 to about 1160, these studies look at three specific themes over a period of more than 1000 years, stretching from late Antiquity to early modern times. They concentrate on the eleventh and twelfth centuries, however, and are designed to examine the thesis put forward in the Reformation concerning the nature and significance of the religious changes at that time.

Each of these studies was originally presented as a lecture, and two of them subsequently as series of lectures, and in spite of extensive revision they bear the marks of their origins. The ‘Orders of society’ was given first at St Mary's College in Notre Dame, Indiana, in 1961 and in a completely rewritten version at Columbia University in 1990, when it benefited from the comments of Elizabeth A.R. Brown and John Baldwin. The ‘Imitation of Christ’ began in 1964 as a lecture at (I believe) Johns Hopkins University and was expanded in 1986 into a series for the Centre d'études supérieures de civilisation médiévale of the University of Poitiers. ‘Mary and Martha’ originated as a chapel talk at Harvard University in 1968 and was the subject, in close to its present form, of a series of lectures at Oberlin College in 1993.