What doctrine formally defined at the Fourth Lateran Council explains the change of bread and wine into Christ’s body and blood?

The story behind the answer

At Lateran IV (1215), the Church defined that in the Eucharist the substance of bread and wine is changed into Christ’s Body and Blood, while their appearances—taste, color, weight—remain. This uses Aristotelian language of substance and accidents to explain how the elements truly become Christ without sensory change, anchoring medieval sacramental theology and liturgy.

This teaching answered medieval debates (e.g., after Berengar of Tours) and distinguished Catholic belief from alternatives: Real Presence names the fact of Christ’s true presence without specifying how; consubstantiation says Christ is present alongside unchanged bread and wine; impanation likens the union to the Incarnation, God “in bread.” The Lateran formula became standard in scholasticism (notably in Aquinas) and was reaffirmed at the Council of Trent.