This book has as its purpose the study of the political and economic relations between the bishop and the chapter in the cathedral churches of twelfth-century England. In particular it is an essay on the historical development of the mensa episcopalis and the mensa capitularis which resulted in the gradual separation of the two endowments and the emergence of the chapter as a largely independent community of clergy. The word mensa, although difficult to define precisely in a single sentence, is used here to refer to the entirety of property and goods which, as capital and income, served to support the members of an ecclesiastical body. The chronological limits of the title should be taken as approximate and suggestive, rather than as absolute and determinate. Precisely dated years of change, and especially the tyranny of the century, rarely work out as well as they appear to do, or as those who use them intend that they should. Although its origins are to be found in the Anglo-Saxon period, the most important changes which affected the cathedral mensa occurred in the first hundred years after the Conquest. By the 1150s, in most of the sees, a permanent division of property had been made.