The Rosary Light & Life - Vol 49, No 3, May-June 1996

Theology for the Laity


By Father Paul A. Duffner, O.P.

Our Blessed Lord celebrated the first Mass at the Last Supper the night before He died. By His divine power He changed bread and wine into His own Body and Blood, so that He might institute a sacred rite whereby the sacrifice that He was to offer to the Father on Calvary the following day could be renewed through the centuries in a sacramental way. In order that His sacrifice on Calvary be perpetuated, during that same meal He conferred on the apostles the power to effect that same miraculous change. "Do this in memory of Me" (Lk. 22:19).

The Liturgy refers to the Eucharist - which is both a sacrifice and a sacrament - as a "mystery of faith." We can attempt to explain what Christ did at the Last Supper as described in the Gospels, but it will still remain a mystery that we believe because of our faith in His word. In no way can we come up with a natural explanation of this miraculous change and of His abiding presence which results from it. Nowhere in nature do we find a change similar to this. We will examine briefly the Churchís teaching on this central doctrine of our faith.


Martin Luther admitted the real presence of Christ in the Eucharist. However, he rejected the doctrine of transubstantiation and taught that the glorified Body of Christ is present in the Eucharist along with the bread and wine (consubstantiation); and he restricted the real presence to the moment of receiving Communion. Other reformers held that the Body of Christ is present only as a sign, that the words of Christ are to be taken in a figurative or symbolic sense, not in their literal meaning.

Confronted with these challenges to the traditional Catholic teaching on the Eucharist by the Protestant reformers, the Council of Trent issued an authoritative teaching on this change of the substance of the bread and wine at the consecration of the Mass.

We are dealing here with something that cannot be verified or even examined by natural science. The nature of the change brought about in the Eucharist, as taught by the Church, lies beyond what chemistry, physics or biology are able to establish. We have it on the clear words of Our Lord, and we can only assent to it through the supernatural light of faith. But it will be helpful to examine a bit in detail various aspects of this doctrine of the Church.


One thing that might be a source of confusion in this matter is that the Church in the expression of this doctrine uses the word "substance" as it is understood in philosophy. In everyday communication we speak of a substance as something we can see, or feel, or taste, etc. However, in philosophy a distinction is made between what a thing is in itself (its substance), and the perceptible qualities or characteristics which exist in that substance (its accidents).

So, in discussing the question of the Eucharist, theologians make the distinction between what they call the substance of the bread and wine, i.e. the reality underlying all its visible, tangible, measurable qualities of the bread and wine, but which in itself is not visible, or tangible, or measurable - for it has no extension in space; and the accidents or appearances of the bread and wine - in which are included all those outward characteristics which can be perceived by the sense of sight, taste, touch, smell and hearing. All such characteristics, as we said, in philosophical language are referred to as "accidents" (not to be confused with the common meaning of that word).

When at the consecration of the Mass the words are pronounced "This is My Body," in an instant the underlying substance of the bread is changed into the BODY, BLOOD, SOUL and DIVINITY of Christ. By the power of the words of consecration, the substance of the bread is changed into the Body of Christ. However, Christ cannot be divided. The living God-Man becomes present at those words. There can be no physical separation of the Body of Christ from the Blood that flows in His glorified Body; nor can there be a separation of His Body from the human soul that gives life to that Body; nor can that human body and soul be separated from the Divine Word with which it was united at the moment of the Incarnation. For this reason the whole Christ (Body, Blood, Soul and Divinity) is present by reason of concomitance," as theologians call it, at the instant the words of consecration are pronounced.

In like manner when, at the consecration of the Mass, the words are pronounced "This is My Blood," by the power of the words there is present the Precious Blood of Christ. Yet, "by reason of concomitance" that is, by reason of the necessary unity of Christ, there is present the Body, Blood, Soul and Divinity of Jesus.

This is why the faithful who communicate only under the species of the bread receive the whole Christ no less than those who partake also of the chalice. To receive Communion under both species might, for some, symbolize or express more vividly the sacrifice of Christ in which His Blood was shed; but in itself it does not bring more grace. The grace of the sacrament depends more on the openness of heart to the One received, i.e. detachment of soul from those things that tend to enslave the heart.


In spite of the fact that there is a complete and total change of substance of the bread and wine at the words of consecration, the appearances or perceptible characteristics, (the accidents) remain the same. What we see and touch and feel, etc., our senses would tell us, is bread and wine. But the reality beneath those appearances, our faith tells us, is the person of Jesus, Body, Blood, Soul and Divinity. The outward visible characteristics of bread and wine truly continue to exist, so our senses do not deceive us. However, by the power of God those outward characteristics are sustained in existence without the substance in which they formerly existed - to serve as an external sign for the sacrament of the Eucharist. Pope Leo XIII spoke of this in his encyclical "Mirae Caritatis:"

St. Thomas Aquinas gives three reasons why it is fitting that God intervenes in this miraculous way (III, 75, 5).

  1. Because it is not customary but horrible for men to eat human flesh and drink human blood; hence Christís flesh and blood are given to us under the species of those things more commonly consumed by men.
  2. Lest this sacrament might be derided by unbelievers, were we to eat the flesh and blood of Jesus under his own proper species.
  3. That while we receive Our Lordís Body and Blood invisibly, this may redound to the merit of faith.

Hence there is no parallel to this in all of nature where there is a complete change of substance, while there is no change in the external sense-perceptible characteristics of the original substance. In fact, every time the priest at Mass pronounces the words of consecration there is a double miracle wrought by the power of God, a miracle not witnessed by the senses, but known only by the light of faith:

  1. The miraculous change of the substance of the bread and wine into the substance of Christís Body and Blood;
  2. The miracle by which God sustains in existence the perceptible qualities or characteristics of the bread and wine, although the underlying substance no longer exists. St. Thomas wrote so beautifully of this mystery in the eucharistic hymn sung at Benediction of the Blessed Sacrament: "Praestet fides supplementum sensuum defectui." (Faith supplies what the senses cannot perceive)


As we have pointed out, when we receive Holy Communion, we receive Jesus, the God-man who suffered died and rose for us. Our divine Savior is not only present in each and every consecrated host, but in every part of each host. Just as before the consecration each part of the host was bread, and every drop in the chalice was wine, so after the consecration every smallest particle of the consecrated host contains the whole Christ, and every drop of the contents of the chalice contains the whole Christ, Body, Blood, Soul and Divinity. Consequently Christ is not divided by the breaking of the host.

We must be careful, however, about imagining how Christ could be present in the small host, or in a tiny part of it. First of all, Jesus is not present in the sacred host in miniature, or in a condensed manner. As St. Thomas Aquinas explains, "Christís Body is in this sacrament Ďby way of substance,í not by way of quantity" (III,76,1,ad 3) that is, not by extension in space. The whole Christ is present in this sacrament with all the faculties and characteristics of His glorified body; but it is an entirely supernatural and unique presence made possible by the power of God, and discerned only by the eyes of faith. As St. Ambrose reminds us, "The word of Christ which could make out of nothing that which did not exist, can it not change things already in existence into that which they were not?"

Christ is present in the Eucharist as He exists now in heaven, that is, in His glorified body. When Our Lord changed the bread and wine into His Body and Blood at the Last Supper, it was His mortal body, for He had not yet died and risen with His glorified body that was immortal. If there are on record miraculous cases where the Sacred Host has bled, that does not change the fact that the presence of Christ in the Eucharist is the glorified Christ. Our Lord could manifest this mark of His passion in this way to emphasize the fact that the Eucharist is a sacrifice (spiritually renewed at Mass) as well as a sacrament. Pope Leo XIII adds another reason:

Too, one might wonder how long does the bodily presence of Christ in His physical reality (i.e. His sacramental presence) remain with us after we receive Him in Holy Communion. He remains with us in His sacramental presence as long as the species of bread and wine retain their true characteristics of bread and wine. Just as true bread and wine can corrupt, or undergo chemical change, so that it is no longer bread or wine, so can the species of bread and wine in the Eucharist undergo such a change, as happens when we receive Holy Communion. When the species of bread in the consecrated host changes within the body so that it no longer has the characteristics of true bread, then the sacramental presence of Jesus ceases. The same is true of the species of wine if one received this sacrament under that form as well as receiving the consecrated host (St.Thos. III,77,4). The reason for this is that the Sacrament of the Eucharist is the Body and Blood of Christ really present under the species or characteristics of bread and wine. If the characteristics of bread and wine cease to be present, the sacrament no longer exists, and the sacramental presence of Christ ceases. However, His spiritual presence through grace, not only remains, but has been increased through the reception of the sacrament.


Although Christ ascended into heaven depriving mankind of his visible presence, He remains with us hidden beneath the veil of the Eucharistic host to continue on the work of redemption, making intercession for us before the Father through the renewal of His sacrifice and His abiding presence. Faith alone makes us aware of His presence, for reason cannot comprehend it. Yet reason knows that what is of divine faith and divinely revealed is infallibly certain. Christ is present in the Eucharist with all the perfections of his humanity together with the infinite grandeur of His divinity, both of which are hidden under the appearances of bread and wine, as St. Thomas expresses so beautifully in the hymn "Adoro Te:"

"In cruce latebat sola Deitas
At hic latet simul et humanitas."

(On the Cross was hidden only His divinity,
But here lies veiled also His humanity.)

Our Savior present in the Eucharist is identical with the Jesus Christ of history, with the Jesus before whom the angels and saints of heaven worship in awe. He is the same Jesus whom Mary brought forth into the world, whom the shepherds found wrapped in swaddling clothes in a manger . . . the same Jesus who taught the multitudes . . . who cured the leper, the blind, the lame and raised the dead . . . the same Jesus who was transfigured on Mt. Tabor . . . the same Jesus who received the kiss of the traitor, was scourged, crowned with thorns, spat upon and treated as a fool . . . the same Jesus who was crucified to redeem us, rose from the dead, and is seated at the right hand of His Father. And to think that at times kneeling before the Tabernacle we cannot think of anything to say!

While our reflection of Christ in the Eucharist centers mainly around his sacred humanity, it is a divine Person that we receive in Holy Communion, the only-begotten Son of the Father. Yet, the divine Word is never alone, for the Father abides in the Son and the Son in the Father, and both are united in the Holy Spirit, all possessing the same divine nature (Jn.14:11). Thus the divine Trinity of Persons, of whose vision is the beatitude of heaven, abides with the Word in the Eucharist Host.

Yet, our primary attention to Christ in the Eucharist will always be centered on Him in His sacred humanity, precisely because He took on our human nature to live and suffer the torturous death that He did - to show us the love of the Father for mankind, and to teach us by word and example how to return that love. In receiving this sacrament we receive Him who is infinite Love, and all the gifts and blessings of the Incarnation and Redemption are made available to us in the measure that is proportionate to our eagerness to receive them. That is to say, the love (not necessarily an emotional disposition) with which we receive our Eucharistic Lord will determine the extent to which this sacrament produces its principally intended effect, namely, transforming the soul into the likeness of Christ. Fr. M.M. Philipon, O.P. speaks of this:

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