[The following is an excerpt from Pope Paul VI’s encyclical Mysterium Fidei, this section being on the reality of the true presence of Christ in the Holy Eucharist, with reference to some of the Fathers of the Church.]
…To avoid misunderstanding this sacramental presence which surpasses the laws of nature and constitutes the greatest miracle of its kind we must listen with docility to the voice of the teaching and praying Church. This voice, which constantly echoes the voice of Christ, assures us that the way Christ is made present in this Sacrament is none other than by the change of the whole substance of the bread into His Body, and of the whole substance of the wine into His Blood, and that this unique and truly wonderful change the Catholic Church rightly calls transubstantiation. 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 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, since after the change of the substance or nature of the bread and wine into the Body and Blood of Christ, nothing remains of the bread and wine but the appearances under which Christ, whole and entire, in His physical “reality” is bodily present, although not in the same way that bodies are present in a given place.
For this reason the Fathers took special care to warn the faithful that in reflecting on this most august Sacrament, they should not trust to their senses, which reach only the properties of bread and wine, but rather to the words of Christ which have power to transform, change and transmute the bread and wine into His Body and Blood. For, as those same Fathers often said, the power that accomplishes this is that same power by which God Almighty, at the beginning of time, created the world out of nothing.
“We have been instructed in these matters and filled with an unshakable faith,” says St. Cyril of Alexandria, at the end of a sermon on the mysteries of the faith, “that that which seems to be bread, is not bread, though it tastes like it, but the Body of Christ, and that which seems to be wine, is not wine, though it too tastes as such, but the Blood of Christ . . . draw inner strength by receiving this bread as spiritual food and your soul will rejoice.”
St. John Chrysostom emphasizes this point, saying: “It is not the power of man which makes what is put before us the Body and Blood of Christ, but the power of Christ Himself who was crucified for us. The priest standing there in the place of Christ says these words but their power and grace are from God. ‘This is My Body,’ he says, and these words transform what lies before him.”
Cyril, Bishop of Alexandria, is in full agreement with the Bishop of Constantinople when he writes in his commentary on the Gospel of St. Matthew: “Christ said indicating (the bread and wine): ‘This is My Body,’ and “This is My Blood,” in order that you might not judge what you see to be a mere figure. The offerings, by the hidden power of God Almighty, are changed into Christ’s Body and Blood, and by receiving these we come to share in the life-giving and sanctifying efficacy of Christ.”
Ambrose, Bishop of Milan, dealing with the Eucharistic change, says: “Let us be assured that this is not what nature formed, but what the blessing consecrated, and that greater efficacy resides in the blessing than in nature, for by the blessing nature is changed.” To confirm the truth of this mystery, he recounts many of the miracles described in the Scriptures, including Christ’s birth of the Virgin Mary, and then turning to the work of creation, concludes thus: “Surely the word of Christ, which could make out of nothing that which did not exist, can change things already in existence into what they were not. For it is no less extraordinary to give things new natures than to change their natures.
However, there is no need to assemble many testimonies. Rather let us recall that firmness of faith with which the Church with one accord opposed Berengarius, who, yielding to the difficulties of human reasoning, was the first who denied the Eucharistic change. More than once she threatened to condemn him unless he retracted. Thus it was that our predecessor, St. Gregory VII, ordered him to pronounce the following oath:
“I believe in my heart and openly profess that the bread and wine which are placed upon the altar are, by the mystery of the sacred prayer and the words of the Redeemer, substantially changed into the true and life-giving flesh and blood of Jesus Christ Our Lord, and that after the Consecration, there is present the true Body of Christ which was born of the Virgin and, offered up for the salvation of the world, hung on the Cross and now sits at the right hand of the Father, and that there is present the true Blood of Christ which flowed from His side. They are present not only by means of a sign and of the efficacy of the Sacrament, but also in the very reality and truth of their nature and substance.”
These words fully accord with the doctrine of the mystery of the Eucharistic change as set forth by the ecumenical councils. The constant teaching of these councils — of the Lateran, of Constance, Florence and Trent — whether stating the teaching of the Church or condemning errors, affords us an admirable example of the unchangingness of the Catholic Faith.
After the Council of Trent, our predecessor, Pius VI, on the occasion of the errors of the Synod of Pistoia, warned parish priests when carrying out their office of teaching, not to neglect to speak of transubstantiation, one of the articles of faith. Similarly our predecessor of happy memory, Pius XII, recalled the bounds which those who undertake to discuss the mystery of transubstantiation might not cross. We ourself also, in fulfillment of our apostolic office, have openly borne solemn witness to the faith of the Church at the National Eucharistic Congress held recently at Pisa.
Moreover the Catholic Church has held on to this faith in the presence in the Eucharist of the Body and Blood of Christ, not only in her teaching but also in her practice, since she has at all times given to this great Sacrament the worship which is known as Latria and which may be given to God alone. As St. Augustine says: “It was in His flesh that Christ walked among us and it is His flesh that He has given us to eat for our salvation. No one, however, eats of this without having first adored it . . . and not only do we not sin in thus adoring it, but we would sin if we did not do so”…