Originally published in French in 1981, and in English translation in 1983, this book examines aristocratic and religious conceptions of marriage between roughly 900 - 1200. His technique is a close analysis of surviving written accounts - treatises, letters, family histories - and so necessarily focuses on the social elite, the families of kings and great lords. Not being a specialist in this period, most of the names slid off me; but Duby excels at drawing overarching lessons and trends from his materials. In brief, he identifies the period as starting with different theories of marriage (and men's sexual behavior generally) held by elite families and the church, driven by different concerns. Noble wanted heirs as well as sexual pleasure, and so were prepared to set divorce wives and remarry for heirs or political advantage, take concubines, and value a certain degree of consanguinity as a guarantee of common interests. Churchmen, in contract, tended to regard sex as a necessary evil, wanted nobles to not marry relatives but otherwise stay married, and wanted priests to be celibate. According to Duby, those conflicting goals reached greatest tension in the years around 1100, with heads of the great families marrying off their daughters for family advantage, and not letting younger sons marry at all in an effort to keep amassed family holdings from getting broken up. By 1200, rapid economic growth provided economic surplus that allowed family chiefs to relax a little and let younger sons start marrying. Duby also suggests that the social unrest provoked by unmarried younger sons - whose main hope of advancement was to abduct a maid from a higher-status family - helped drive the shift in attitudes. One amusing, counter-intuitive aspect of the whole period is the assumption, in church law but also implicitly in family chronicles, that sex among unmarried men (and the women they slept with) was no big deal, while enthusiastic sex within marriage, for purposes beyond procreation, was sinful and suspect. A second, unamusing but pervasive theme in the period - Duby calls it out repeatedly - is the sheer misogyny with which churchmen, nobles, and men in general appeared to regard all women of any social class.