On the Sacrifice of Unleavened and Leavened Bread

The Epistola de Sacrificio Azymi et Fermentati (Letter on the Sacrifice of Unleavened and Leavened Bread) is Anselm of Canterbury's reply to Walram, bishop of Naumburg in Saxony, who had written asking how to answer Greek Christians who condemned the Latin use of unleavened bread in the Eucharist. Anselm wrote it around 1106–1107, near the end of his life, after his return to England from exile. It belongs with his De processione Spiritus Sancti, which grew out of his defense of Latin doctrine before the Greeks at the Council of Bari in 1098, and with a companion letter to Walram, De sacramentis ecclesiae, which takes up other differences in sacramental custom. Together these form Anselm's contribution to the East–West controversy a half-century after the rupture of 1054.

Anselm's method is characteristically spare. He begins by refusing the premise that one practice must invalidate the other: Christ took bread, and bread is bread whether leavened or unleavened, so the sacrifice is true in either case. He then argues that the Latin custom is nonetheless the more fitting, because Christ instituted the sacrament at Passover, when by the Law no leaven was to be found in the house, so that the Latins simply do what Christ did. He meets the Greek charge of Judaizing by distinguishing imitation of Christ from observance of the Law. The remainder of the letter works through the scriptural symbolism on both sides. Leaven in Scripture most often signifies corruption and malice, as in Paul's command to purge out the old leaven and keep the feast with the unleavened bread of sincerity and truth, and in Christ's warning against the leaven of the Pharisees; unleavened bread therefore aptly signifies the purity of the body of Christ. Yet Anselm will not press the figure into a weapon. He notes that Christ also likens the kingdom of heaven to leaven, so leavened bread cannot be called impure in itself, and he rejects the Greek claim that unleavened bread is somehow dead or deficient. His conclusion is measured: the Latins do not condemn what the Greeks do, but they rightly refuse to be condemned for doing what Christ himself did.

The letter matters less for the dispute it addresses, which few now feel acutely, than for the temper it displays. In a controversy that elsewhere produced invective, Anselm separates what is essential to a sacrament from what is fitting in its celebration, grants validity to a rival custom, and still argues his own case with conviction. That combination of charity and rigor is why the text remains cited in discussions of Eucharistic theology and of medieval ecumenical method.

Who should read this: students of Eucharistic theology, of the Latin–Greek schism, and of Anselm's thought beyond the Proslogion and Cur Deus Homo, as well as anyone interested in how a theologian can disagree without anathematizing. It is a brief, technical letter, not a devotional work, and readers seeking spiritual counsel or the sweep of Anselm's prayers and meditations should look elsewhere.