What is transubstantiation?
The short answer
Transubstantiation is the Church's word for what happens at the consecration of the Mass: the whole substance of the bread and wine becomes the body and blood of Christ, while the outward appearances of bread and wine remain.
A precise word for a real change
The Council of Trent (1551) taught that "by the consecration of the bread and wine there takes place a change of the whole substance of the bread into the substance of the body of Christ… and of the whole substance of the wine into the substance of his blood. This change the holy Catholic Church has fittingly and properly called transubstantiation" (quoted in CCC 1376).
The word was not invented to create a new belief. The Church had always believed the bread and wine become Christ. The term was adopted in the Middle Ages (it appears at the Fourth Lateran Council in 1215) to describe that belief precisely and to rule out vaguer explanations.
Substance and appearances
The explanation borrows a distinction everyone uses without thinking:
- Substance — what a thing is.
- Accidents (appearances) — what it looks, tastes, weighs and feels like.
Normally, when appearances change, the substance may stay the same — water is still water as ice or steam. In the Eucharist the opposite happens: the substance changes completely while the appearances stay. That is why no laboratory could detect the change, and why the Church does not claim it could.
How long Christ remains present
Christ remains present as long as the appearances of bread and wine remain (CCC 1377). This is why consecrated hosts are reserved in the tabernacle, brought to the sick, and adored.
What it is not
- It is not a claim that Christ's body is broken into pieces. Christ is whole and entire in each host and each drop (CCC 1377).
- It is not cannibalism. Christ is received in his risen, glorified life, not as dead flesh.
- It is not magic. The change happens by the power of Christ's word and the Holy Spirit, not by a formula the priest controls.