What does it mean that Jesus Christ is present in the Eucharist under the appearances of bread and wine?  How does this happen?

The real presence of the risen Christ in the Eucharist is an inexhaustible mystery that the Church can never fully explain in words.  We must remember that the triune God is the creator of all that exists.

As St. Ambrose said: “If the word of the Lord Jesus is so powerful as to bring into existence things which were not, then all the more so those things which already exist can be changed into something else.”

In chapter 6 of the Gospel taken from John, we read things such as, “I am the living bread that came down from heaven . . . for my flesh is true food, and my blood is true drink.”

The whole Christ is truly present, body, blood, soul, and divinity, under the appearances of bread and wine—the glorified Christ who rose from the dead after dying for our sins.  This presence of Christ in the Eucharist is called “real” not to exclude other types of his presence as if they could not be understood as real.

The Catechism of the Catholic Church tells us that the Eucharist is the source and summit of our faith.  The risen Christ is present to his Church in many ways, but most especially through the sacrament of his Body and Blood.

We celebrate the Mass . . . the Eucharist . . . the Lord’s Supper . . . the Blessed Sacrament . . . Holy Communion . . . transubstantiation . . . by whatever name it is called, Catholics have believed and taught about this awesome reality from the very beginnings of the Church instituted by Christ. (8:40)