Transubstantiation was a word brought into usage by St. Thomas Aquinas as he tried to understand the mystery of the Real Presence. Using the Greek philosopher Aristotle as a guide, he saw that the material things of the earth had both substance and accidents. This sounds, at first glance, like very philosophical language, but when it is put into a concrete example it easy to understand the distinction. For example, if we were looking at a table, we would say that its substance is wood, but its accidents are that it is of a certain shape, color or height. Now, to bring the example into bread, when we look at a loaf of bread we see that its substance is that of bread, but its accidents may be that it is of a certain size or shape. And to bring the idea even more closely to what we are looking at, if we look at a host prior to its consecration at Mass, we see a host that is the substance of bread and has the accidents of being a certain size and shape.
For St. Thomas, something nothing short of miraculous takes place at Mass – at the words of consecration, the accidents of the host remain, it is still of a certain size and shape and appearance, but its substance has changed – it is no longer the substance of bread, it is now the substance of Jesus Christ Himself – of His Body, Blood, Soul and Divinity. In that sense, then, the appearance of bread and wine become like a veil, which veils from our human sight what they actually now are.
It was the Scholastic mind of St. Thomas that helped to understand the mystery more clearly, but the belief in the Real Presence is something that goes back to the very beginning of the Church. We see St. Ignatius of Antioch writing in the year 110 AD write, “I desire the Bread of God, the heavenly Bread, the Bread of Life, which is the flesh of Jesus Christ, the Son of God…I wish the drink of God, namely His blood…” (Letter to the Romans). St. Irenaeus of Lyons writing in 180 AD writes, “just as bread from the earth, when it receives the invocation of God, is no longer common bread but the Eucharist, made up of two elements, one earthly and one heavenly” (Against Heresies). St. Cyril of Jerusalem in one of his post-Easter catechesis sermons in 350 AD says, “these things having been learnt, and being fully persuaded that what seems bread is not bread, though bread by taste, but the Body of Christ; and that what seems wine is not wine, though the taste will have it so, but the Blood of Christ.” These witnesses to the ancient belief of the Real Presence show how our own beliefs in the Eucharist continue in this same understanding that they had, that when Jesus said, “this is my Body and this is my Blood” and, “unless you eat the flesh of the Son of Man and drink his blood you do not have life within you” and “my flesh is true food and blood is true drink” He was speaking the truth.
(This article is part of a series of articles on The Sacraments which will appear in the bulletin over the course of this year.)