Anselm of Canterbury, Saint: Cur Deus Homo

Cur Deus Homo, why God became man, is Anselm of Canterbury’s treatise on the incarnation and redemption, in two books. In the preface Anselm explains that he had to finish it more quickly and briefly than he wished, because some people were copying the early parts without his knowledge; he began it in England amid great tribulation and completed it as an exile in the province of Capua. The first book presents the objections of unbelievers who reject the Christian faith as contrary to reason, and, setting Christ aside as if he had never existed, proves by necessary reasons that no one can be saved without him. The second shows that man was created for blessedness and that only a God-man can make satisfaction for sin.

The work, written as a dialogue between Anselm and his pupil Boso, is one of the most influential works of medieval theology. Its argument that sin is a debt of honour owed to God, which humanity owes but cannot pay and only God can pay, set the terms of Western discussion of the atonement for centuries. Its method of seeking necessary reasons for articles of faith is a landmark in the development of scholastic thought.