The Catechism begins its teaching on this doctrine at paragraph 1373. I left the Eucharist part one at paragraph 1344. Those sections after this talk about the Mass and contain teachings on why we celebrate this sacrament. For the purposes of this post, the focus will be on specifically transubstantiation.
What does this long word mean anyway? Essentially it is the belief that Christ is physically present in the bread and wine after the priest consecrates them on the altar. So they are no longer bread and wine, but are now the body and blood of Christ (hence also the reason for the feast of Corpus Christi). Christ’s presence is also affirmed in Scripture:
“Where two or three are gathered in my name, I am there.” – Matthew 18:20
“Whatever you did for the least of these brothers or sisters of mine, you did for me.” – Matthew 25:40
Christ is also present at the celebration of any sacrament of the Church, since he authored them, but “most especially in the Eucharistic species,” (CCC 1373). His presence in the Eucharist is what elevates it to being “the sacrament of sacraments.” Thomas Aquinas wrote that the Eucharist is “the perfection of the spiritual life and the end to which all the sacraments tend,” (CCC 1374). The Council of Trent stated that in the Eucharist “the body and blood, together with the soul and divinity, of our Lord Jesus Christ and, therefore, the whole Christ it truly, really, and substantially contained.” This presence is more “real” because it is “a substantial presence by which Christ, God and man, makes himself wholly and entirely present,” (CCC 1374).
Transubstantiation is part of the reason non-Catholics are asked to not participate in the Eucharist. Most Protestant denominations believe in a symbolic view of the Eucharist, that Christ’s body and blood are symbolized in the bread and wine. Catholicism teaches that it is actually the body and blood of Christ, not a symbol.
Here some may say, “Why wait until the 1500s to clarify this? Why not earlier?” To answer, many theological issues had no need to be fleshed out in such a way because the majority of people believed it. When the dynamic changes, the Church in response will solidify its position on a teaching. This is true not only for transubstantiation, but for other doctrines and teachings like Christ’s dual natures or Marian beliefs.
In fact, many early Church fathers promoted the belief in transubstantiation. Thomas Aquinas was mentioned above, and others like John Chrysostom and Ambrose also spoke about this.
“It is not man that causes the things offered to become the Body and Blood of Christ, but he who was crucified for us, Christ himself. The priest, in the role of Christ, pronounces these words, but their power and grace are God’s. This is my body, he says. This word transforms the things offered.” – John Chyrsostom
“Be convinced that this is not what nature has formed, but what the blessing has consecrated. The power of the blessing prevails over that of nature, because by the blessing nature itself has been changed… Could not Christ’s word, which can make from nothing what did not exist, change existing things into what they were not before? It is no less a feat to give things their original nature than to change their nature.” – Ambrose of Milan (CCC 1375)
The Council of Trent said it in this way: “Because Christ our Redeemer said that it was truly his body that he was offering under the species of bread, it has always been the conviction of the Church of God, and this holy Council now declares again, that by the consecration of the bread and win there takes place a change of the whole substance of the bread into the substance of the body of Christ our Lord 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.” (CCC 1376)
Another fellow Catholic blogger also points out that no one up until the Protestant Reformation disputed transubstantiation and, as pointed above, the early Fathers in fact promoted this belief.
Biblical evidence of this claim is also found not only at the Last Supper, but also in John 6. After Jesus feeds the multitude of people, they come back wanting more. Jesus tells them that he is the bread of life and that this bread is his flesh (vv. 35-51). The crowd is then perplexed: How can Jesus give them his flesh (v. 52)?
Jesus answers, “Very truly I tell you, unless you eat the flesh of the Son of Man and drink his blood, you have no life in you. Whoever eats my flesh and drinks my blood has eternal life, and I will raise them up at the last day. For my flesh is real food and my blood is real drink. Whoever eats my flesh and drinks my blood remains in me, and I in them. Just as the living Father sent me and I live because of the Father, so the one who feeds on me will live because of me. This is the bread that came down from heaven. Your ancestors ate manna and died, but whoever feeds on this bread will live forever.” (vv. 53-58)
After this, many of these disciples leave him because they cannot swallow his teaching. Typically, Jesus would explain more if it were symbolic, like he does for parables. Here, he essentially says, “Here it is. Take it or leave it.” And it is difficult to fathom; our minds cannot process it. It is simply a matter of faith. The food that looks like bread and tastes like bread is not bread, but Christ’s body. The drink that looks like wine and tastes like wine is not wine, but Christ’s blood.