Step-by-Step Walk Through the Mass

Do This in Remembrance of Me, Part 50: Transubstantiation

I often hear people ask why it is that, for so many priests, the Consecration is their favorite moment of the Mass. How exactly does the Consecration “work”?

Thanks for asking! Some years ago, I was in the midst of a large assignment by myself and was struggling with some health issues. I was working long days to try and cover all that was needed, but I felt myself regularly falling short. Around that time, I was gifted with a wonderful confession from one of our wise priests, who reminded me that the best and most important part of my day is always what happens at the altar. He said I could end the day with unfinished projects and unanswered messages, but if I prayed the Mass faithfully at the altar, then it will have been a great day. What great words of consolation!

Catholic priest raising the host during the Consecration at Mass

At the moment of the Consecration and the elevation that follows, I am always reassured that I am exactly where I am supposed to be: I am answering the call God gave to me to serve as a priest. As we all are, I am a work in progress, and some days feel like much more progress is needed. However, in that moment of the Mass, I am always comforted and strengthened, humbled and invigorated. Because I can be a perfectionist, I don’t always receive compliments well; because I have a quick mind, I’m often thinking of problems to solve and things that need to be done. But in that moment of the Mass is true rest and peace. If you are like me and often have a preoccupied mind, I invite you in that special moment of the Mass to enjoy resting in his peace. Remind yourself that there is no better place to be in that moment than united with Jesus truly present on the altar.

How the Consecration Effects Transubstantiation

How exactly does the Consecration work? Let’s turn to our Catechism for some helpful wisdom. “It is by the conversion of the bread and wine into Christ’s body and blood that Christ becomes present in this sacrament. The Church Fathers strongly affirmed the faith of the Church in the efficacy of the Word of Christ and of the action of the Holy Spirit to bring about this conversion. Thus St. John Chrysostom declares: ‘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’” (CCC, 1375). The Catechism tells us that the word of Jesus is what changes the bread and wine into his Body and Blood.

Painting of the Last Supper with Jesus and his disciples

The Catechism continues, “The Council of Trent summarizes the Catholic faith by declaring: ‘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 wine there takes place a change of the whole substance of the bread into the substance of the body of Christ our Lord and 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). For many of us, transubstantiation can be a big and intimidating word. The reason we use words like these is that they help us describe with precision what we believe is true. Transubstantiation helps us know that the “what it is” is what changes during the Mass. As we said before regarding the gifts, what they are before the consecration is simple bread and wine. Those words of Jesus change the bread and wine into his Body and Blood. Even though the appearances remain, we believe that the whole Christ is present in the consecrated host and chalice. As our Catechism teaches, the reason we believe that Jesus is present is because Jesus said it. We believe him when he says: “This is my Body.” We believe him when he says “This is my Blood.” We believe that the Eucharist really is Jesus. The same Jesus who was born in Bethlehem, the same Jesus who offered himself on the Cross—Jesus is truly with us!

Gold vessels filled with Communion hosts for Mass

Seeing with Eyes of Faith

“But Father, the host still ‘looks’ the same!” some may say. St. Cyril of Jerusalem (314–386) teaches, “Do not think these are just plain bread and plain wine. They are the body and blood of Christ, as the Lord asserted. Faith must convince you of the latter even though your senses suggest to you the former. Do not judge about this according to your preferences but, based on your faith, believe with firmness and certainty that you have been made worthy of the body and blood of Christ” (Understanding the Mass, pp. 140–141). If your faith feels unsure, ask the Lord to help you see with the eyes of faith that he is truly there. Let the genuflections and reverence from your body help remind your mind of what we believe is true. Let the model of faith from the saints and the martyrs inspire you. Let our hearts be filled with joy after the consecration, and let us rejoice in recalling that Jesus is sacramentally present. Let us shout with joy the words of St. John, “It is the Lord!” (John 21:7).

For Reflection:

1. Study the Church’s teaching on Christ’s presence “under the Eucharistic species” in the Catechism, paragraphs 1373–1381, or even the entire section on the Eucharist (1322–1419). Consider inviting others to join you in this study to strengthen your faith in the Eucharist and participation at Mass. Consider checking out episodes 180–194 of Fr. Mike Schmitz’s Catechism in a Year, which leads listeners on a journey into the mystery of the Eucharist.

2. Bring St. John’s words, “It is the Lord!” (John 21:7), in your heart to Mass to seek and find Christ’s presence during the Consecration.