This last week in May, either on Thursday or on Sunday, Catholics celebrate Christ’s gift of himself to us in the Holy Eucharist, the sacrament of his Body and Blood. The Feast of Corpus Christi was established in 1264 by Pope Urban IV, who asked St. Thomas Aquinas to compose liturgical texts for the occasion. Among these is the hymn Adoro te devote, which contains the following lines (in Ronald Knox’s translation):

God with hidden majesty lies in presence here.

I with deep devotion my true God revere.

Whom this outward shape and form secretly contains

Christ in his divinity manhood still contains.

All my other senses cannot now perceive

But my hearing, taught by faith, always will believe.

I accept whatever God the Son has said

Those who hear the Word of God by the truth are fed.

“My hearing, taught by faith, always will believe” the true presence of Jesus Christ in what appears to our senses as ordinary bread and wine. Now, faith is a firm assent that we make to something God reveals as true. Thus, in the 6th chapter of St. John’s Gospel, Jesus says, “I am the living bread that came down from heaven; whoever eats this bread will live forever; and the bread that I will give is my flesh for the life of the world.” Many who heard these words of Jesus doubted; they refused their assent to what he was saying. They asked, “How can this man give us his flesh to eat?” Later in the same chapter, we learn that many of our Lord’s disciples left him at this point, when he said, “My flesh is food indeed, and my blood is drink indeed.” They complained: “This is a hard saying; who can listen to it?” Then, when Jesus asked his twelve apostles, “Do you also wish to go away?”, Peter, speaking for them all, replied, “Lord, to whom shall we go? You have the words of eternal life.”

When Catholics come to Communion, what appears as bread is held before us with the words “The Body of Christ,” and when we say “Amen” before receiving it, we are making the assent of faith, the faith of the apostles, the faith of the whole church from her beginning, that what appears to our senses as bread is really (substantially) the body of Jesus Christ our Lord. We assent to it as literally true, that our living Lord is wholly present in each fragment of the Eucharist. He gives himself to us as food, under the sensible sign of bread; and we, receiving him into ourselves, make his heavenly life our own, as Jesus promised: “He who eats my flesh   . . . has eternal life, and I will raise him up at the last day.”

This Eucharistic faith of Catholics can be an embarrassment to other Christians, as it was originally to many of our Lord’s disciples. Even some Catholics are uncomfortable with the doctrine called Transubstantiation, meaning that the substance (or reality) of bread and wine are changed into the body and the blood of Christ. Some have suggested another definition of our faith, which they call “Trans-signification”—that is, the meaning (rather than the substance) of the bread and wine is changed into the body and the blood of Christ. But the “embarrassing” fact remains, that when Jesus instituted the Holy Eucharist, and commanded his apostles to continue what he started, he did not say “This signifies my body, given for you, and my blood, poured out for you,” but “This is my body and my blood.”

The feast of Corpus Christi celebrates our firm and simple faith in God the Son made man, giving his whole self to us as food. How he does this is a mystery, of course. We cannot understand it any more than we can understand how God could make the universe from nothing, solely by his Word. We don’t claim to understand it, only to affirm it and to celebrate it, as Aquinas did in these lines from another of his hymns, Pange lingua (again, in Ronald Knox’s translation):

 By his word the Word almighty makes of bread his flesh indeed.

Wine becomes his very lifeblood; faith God’s living Word must heed.

Faith alone may safely guide us where the senses cannot lead.

Come adore this wondrous presence; bow to Christ, the source of grace.

Here is kept the ancient promise of God’s earthly dwelling place. Sight is blind before God’s glory. Faith alone may see his face.