Recents studies have shown that as many as 50 percent
of Catholics either do not understand or do not believe that Christ is truly present in the Eucharist. And since the Eucharist is the center of our sacramental lives as Catholics, it is essential that we “go back to the basics” and ask, “what is transubstantiation?” and “why do we believe it?”

The Church’s constant teaching has been that at the moment of consecration within Mass the bread and wine are changed in the Body and Blood of Christ. The term that the Church has given to this change is “transubstantiation.” The Latin roots of this word: trans means “to change” and substantia means “substance” or “what a thing is.” And so transubstantiation means, in the case of the Eucharist, that while the “accidents” (appearances) of the bread and wine don’t change, the “substance” (what they are) does change. This means that nothing of the bread and wine remains in the Eucharist, only their appearances. It still looks like bread and wine; it still tastes like bread and wine; but it is actually the Body and Blood of Christ!

This foundational truth, that in the Eucharist the bread and wine changes into the very Body and Blood of Christ, the Church has taught continuously from the very beginning. It began with the teaching of Jesus who said, “The bread that I will give you is my flesh for the life of the world…for my flesh is true food, and my blood is true drink,” and at the Last Supper, lifting up bread and wine, said, “This is my body…this is my blood.” And this teaching continued in a unified way in the writings of the early fathers of the Church. In fact, the issue was not even disputed within the Church until the 9th century.

The teaching was later called into question by the Protestant reformers. Martin Luther admitted the Real Presence of Christ in the Eucharist, however he repudiated transubstantiation and taught that the Body and Blood of Christ are present “in, with, and under” the bread and wine, but that the bread and wine remain (this was later called “consubstantiation”).

The Church reaffirmed its teaching at the Council of Trent in 1551: “It has always been the conviction of the Church of God, and this Holy Council now again declares, that by the consecration of the bread and  wine a

After the Second Vatican Council, transubstantiation was again called into question and certain people were proposing alternative terms, e.g., transignification (the meaning of the bread and wine changes) or transfinalization (the purpose of the bread and wine changes). But Paul VI, in his encyclical Mysterium Fidei, reaffirmed the doctrine of transubstantiation and its timeless quality as something “not tied to a certain form of human culture, nor to a specific phase of human culture, nor to one or other theological school” but as belonging to the universal faith and experience of the Church.

This summer is a great opportunity for us to explore once again the mystery of the Eucharist. A more thorough understanding of transubstantiation is just the beginning: it describes what happens, but certainly does not explain how it happens and what the meaning is for us as believers. The Eucharist is, in fact, an inexhaustible mystery, which we can enter into ever-more deeply with each celebration and each reception.