William of Auvergne was a long-reigning bishop of Paris (1228-1249) with notable political influence, wide intellectual interests, and an appetite for ideological contest. William’s On Laws (De legibus) is a major treatise on the Law of Moses, its nature and purpose in ancient Judaism and contemporary Christianity. William’s fundamental objective in the work is to show the abiding power of the Law, including its ritual and other seemingly non-moral commands, as a counterforce to perennially recurring idolatries. In this, he shows his debt to, but also his distance from, Maimonides, whose Guide of the Perplexed had, in William’s time, only recently appeared (c. 1223) in a partial Latin translation. Along the way, On Laws includes lengthy sections on non-literal biblical interpretation and its abuses; on the life of Muhammad and the law of Islam; and on contemporary superstition, sorcery, and paganism.

On Laws is a work of broad significance for the cultural history of thirteenth-century Europe, including the histories of medieval Jewish-Christian relations, Christian-Muslim relations, heresy, paganism, and witchcraft, as well as the histories, more broadly, of biblical interpretation, philosophy, natural science, and magic. A product of the academic world of early thirteenth-century Paris, On Laws is not a lovely or literary work, but neither is it technical, formulaic, or derivative. The book, like its author, cuts its own paths through the cultural thickets of the day. And by its relative intellectual informality, On Laws gives frequent, inadvertent insight into the intellectual, religious, and social experiences of thirteenth-century people.

On Laws has never before been translated from Latin into any other language.