According to the Preface to St. Anselm of Canterbury's Cur Deus Homo, the work, among other things, “prov[es] by necessary reasons ... that it is impossible for any man to be saved without [Christ].” In the course of this project, Anselm must clarify what is meant by salvation— without knowing this, we could not know whether salvation could be brought only by Christ. Anselm develops an understanding of salvation involving a deliverance from the punishment that is our due because of our sin, and a correlative restoration to blessedness, which deliverance and restoration are made possible by Christ’s “satisfaction” for sin. Hence, the question of the meaning of salvation and the need for Christ as savior includes the question of the meaning of satisfaction. Now, the Cur Deus Homo has been received as one of the most significant contributions to the Church's understanding of soteriology; most recently one finds echoes of Anselm's understanding of satisfaction in the Catechism of the Catholic Church (no. 615). For this reason it is worth inquiring into what Anselm means by “satisfaction.”
It is my intention in this essay to examine especially those sections of Book I of the Cur Deus Homo which treat the relationship between salvation and our deliverance from the devil, and to propose that one finds in Anselm's understanding of satisfaction a requirement for justice even for the devil (something that Anselm's rejection of the idea that our salvation requires payment of a ransom to the devil has tended to obscure).