On the Body and Blood of the Lord

De Corpore et Sanguine Domini is Lanfranc of Bec's theological treatise defending the doctrine of the real presence in the Eucharist against the challenges posed by Berengar of Tours. Written between 1059 and 1079, this work emerged from one of the most significant eucharistic controversies of the eleventh century, when Berengar's rationalist approach to the sacraments threatened traditional Catholic teaching about the transformation of bread and wine into the actual body and blood of Christ.

Lanfranc constructs his argument through careful exegesis of Scripture, particularly the institution narratives and John 6, combined with appeals to patristic authority and sacramental reasoning. He insists that the consecrated elements undergo a real substantial change while maintaining their outward appearances, articulating what would later be refined into the doctrine of transubstantiation. Against Berengar's claim that the sacrament functions merely as a figure or symbol, Lanfranc argues for the simultaneous reality of Christ's presence in heaven and in the Eucharist, employing sophisticated distinctions about the nature of sacramental causality and divine omnipresence. His method combines dialectical reasoning with traditional theological sources, representing the emerging scholastic approach to doctrinal questions.

This treatise proved foundational for medieval eucharistic theology and influenced the development of sacramental doctrine through the scholastic period. Lanfranc's arguments provided the theological groundwork for the Fourth Lateran Council's formal definition of transubstantiation in 1215, and his integration of rational argumentation with traditional authority became a model for later theological method. The work demonstrates how eleventh-century theologians navigated the relationship between faith and reason in addressing doctrinal challenges.

Who should read this: Students of medieval theology and sacramental doctrine who want to understand the intellectual foundations of Catholic eucharistic teaching, and those interested in the development of scholastic theological method. This is specialized academic material requiring familiarity with medieval Latin theology and sacramental terminology.