O Sacrum Convivium by Fr. Brian Mullady O.P.


“O Sacred banquet, in which Christ is received, the memory of his Passion is celebrated, the soul is filled with grace and the pledge of future glory is given to us.”

This famous Eucharistic antiphon from the feast of Corpus Christi is attributed to St. Thomas Aquinas, and well summarizes both the faith of the Church and the theology of St. Thomas concerning the mystery of the Holy Eucharist.

The doctrine of transubstantiation is central to this teaching. The Fourth Lateran Council in 1215 was the first to formally define the manner in which Christ is present in the Sacrament of the Eucharist:

“There is one Universal Church of the faithful, outside which, no one at all is in a state of salvation. In this Church, Jesus Christ Himself is both priest and sacrifice; and His body and blood are really contained in the sacrament of the altar under the species of bread and wine, the bread being transubstantiated into the body and the wine into the blood, by the power of God, so that, to effect the mystery of unity, we ourselves receive of that which is His, what He Himself received of that which is ours.”

The Fourth Lateran Council used the word “transubstantiation” to summarize a long tradition originating in the Gospels and St. Paul concerning the presence of Christ in the Eucharist.

Transubstantiation occurs after the priest says the words of institution over the bread. This technical term refers to the being of bread changing into the being of the body of Christ while all the properties of bread remain. In the late 1960s I attended a lecture by a famous Catholic theologian given to a large group of Protestant and Catholic seminarians in Berkeley. He declared that if one put the host under a microscope, he would see—according to the doctrine of transubstantiation—the molecules of Christ’s body. Modern scientific investigation had demonstrated that there was no change in molecular structure and so there was no change in substance. As a result, the change must not be a change in being, but only in being perceived by the subject through his faith. The bread now means Christ to him, and he uses it for the purpose of union with Christ. These last ideas are termed generally by modern theology “transignification” (change in meaning) and “transfinalization” (change in purpose).

The difficulties in this position are, first, that it mistakes the philosophical understanding of substance for the modern idea of chemical-molecular substance. Substance in the philosophical sense does not refer to element, but to a being which exists in its own right. Bread is a substance; a rock is a substance. An accident is a being which cannot exist in its own right. White is an accident. White cannot exist apart from a white thing like white bread or a white rock. Transubstantiation, then, does not mean that molecular structure changes, as this is merely an accidental or non-essential aspect of the substance.

Secondly, it is true to say that the change in the Eucharist includes change in meaning and change in purpose, but these changes involve change in nature. In other words, the objective change must support the subjective change. Pope Paul VI expresses it very well:

“As a result of transubstantiation, the species of bread and wine undoubtedly take on a new meaning and a new finality, for they no longer remain ordinary bread and ordinary wine, but become the sign of something sacred, the sign of a spiritual food. However, the reason why they take on this new significance and this new finality is simply because they contain a new ‘reality’ which we may justly term ontological. Not that there lies under those species what was already there before, but something quite different; and that not only because of the faith of the Church, but in objective reality” (Mysterium Fidei, 1965).

By this change in substance, Christ associates us with His Passion, suffered and accepted, and with His Body, resurrected and ascended.

This can only happen if He becomes truly present to us here on earth so that we may participate in the body and blood and make His perfectly obedient soul our own. This sacrament is the bond of love and stimulus for hope, because in this food we become the food. In all other food, the food becomes us. In this we are more and more transformed into Christ. Still, because we only know Him here through faith, this sacrament is also a food for our faith by which all the interior obedience and love of Christ’s human heart becomes the constant nourishment for our spirits. It is the food of pilgrims. Though the Eucharist is a meal/banquet, it is a sacred banquet. When we as pilgrims feed on Christ, we are participating in the heavenly banquet.

By the same token, Christ desires to be intimately present to everyone in His true body and blood. He could not do this if He were only present in the manner His body is present in heaven. The Blessed Sacrament is truly that body, but present in a substantial, sacramental way. His body does not move through space to leave heaven and become present in one altar on earth, then in another. The change of transubstantiation is not just a change in form nor a change in place. It is a true change in substance. The dimensions and quantity of Christ’s risen body remain at the right hand of the Father, but become completely present on all the altars of the world completely and simultaneously. Otherwise we would not all participate equally in the fullness of His obedience and love. “Christ,” the Mystical Lamb of the Apocalypse, “is received.”

Christ instituted this sacrament precisely so that we, the wayfarers and pilgrims, could share fully in the mystery of His atonement. This is a true memorial or anamnesis. He said, “Do this in memory of me.” Yet this is not just a play reenacted. It is a true participation in the whole interior drama of His perfect obedience on the Cross. “The Eucharist is thus a sacrifice because it re-presents (makes present) the sacrifice of the Cross, because it is its memorial and because it applies its fruit” (Catechism, no. 1366). This begins by His association of the apostles with His atonement at the Last Supper. For this reason, all Catholic accounts of the Passion begin not with the agony, but with the Last Supper. The Supper and the Cross are intimately united. The sign and associated effects exist to plunge our own moral lives into the mystery of Christ’s perfect obedience on the Cross.

According to the Catholic faith, after the priest recites the words of institution, every facet and part of Christ is present in the Host (the victim). Not every part is present in the same way, though. Some are present as entailed in the sign, while others are present by natural accompaniment. For example, in the consecration of the Host, only the body becomes present by sacramental sign. The words which induce the change are “This is my body.” The blood is present by natural accompaniment. The property of quantity remains with Christ fully present body and blood, soul and divinity under the appearance of bread.

The miraculous character of this change is expressed because the priest repeats the words of Christ- He speaks in the Person of Christ, not in his own person as minister. In all the other sacraments, the priest speaks in the person of the minister. “I baptize,” “I confirm,” “I anoint.” In this sacrament alone, he speaks directly in the Person of Christ because this sacrament is not only the power of Christ, but is also Christ Himself. “This is My body; This is My blood.” For this reason, it is more than just a tasteless act for the priest to dress, act, or speak as though he were Father X speaking. He is Christ speaking and makes Christ present. This is the Real Presence with capital letters.

“This presence is called ‘real’—by which it is not intended to exclude all other types of presence as if they could not be ‘real’ too, but because it is presence in the fullest sense: that is to say, it is a substantial presence by which Christ, the God- Man, is wholly and entirely present” (Mysterium Fidei).

Since the entire purpose and effect of this sacrament is our union with the whole mystery of Christ, including his Mystical Body the Church, one must be morally prepared to receive it worthily. Moral preparation is freedom from mortal sin.

Such is the great miracle of transubstantiation. Christ Himself becomes present to feed us with the moral value of His atonement and to prepare us morally and physically to live with Him in Resurrection forever. Our bodies are prepared for resurrection. “A pledge of future glory is given to us.”

Fr. Mullady writes from Holy Apostles College & Seminary, Cromwell, CT.