Mysterium Fidei
On the Holy Eucharist
SEPTEMBER 3, 1965
To His Venerable Brothers the Patriarchs, Primates, Archbishops, Bishops and other Local Ordinaries in Peace and Communion with the Apostolic See, and to the Clergy and Faithful of the Entire World.
Venerable Brothers and Dear Sons, Health and Apostolic Benediction.
The Mystery of Faith, that is, the ineffable gift of the Eucharist that the Catholic Church received from Christ, her Spouse, as a pledge of His immense love, is something that she has always devoutly guarded as her most precious treasure, and during the Second Vatican Council she professed her faith and veneration in a new and solemn declaration. In dealing with the restoration of the sacred liturgy, the Fathers of the Council were led by their pastoral concern for the whole Church to regard it as a matter of highest importance to urge the faithful to participate actively, with undivided faith and the utmost devotion, in the celebration of this Most Holy Mystery, to offer it to God along with the priest as a sacrifice for their own salvation and that of the whole world, and to use it as spiritual nourishment.
2For if the sacred liturgy holds first place in the life of the Church, then the Eucharistic Mystery stands at the heart and center of the liturgy, since it is the font of life that cleanses us and strengthens us to live not for ourselves but for God and to be united to each other by the closest ties of love.
Reaffirmation by Vatican II
3In order to make the indissoluble bond that exists between faith and devotion perfectly clear, the Fathers of the Council decided, in the course of reaffirming the doctrine that the Church has always held and taught and that was solemnly defined by the Council of Trent, to offer the following compendium of truths as an introduction to their treatment of the Most Holy Mystery of the Eucharist:
4"At the Last Supper, on the night when He was betrayed, our Savior instituted the Eucharistic Sacrifice of His Body and Blood. He did this in order to perpetuate the Sacrifice of the Cross throughout the centuries until He should come again, and so to entrust to His beloved Spouse, the Church, a memorial of His Death and Resurrection: a sacrament of love, a sign of unity, a bond of charity, a paschal banquet in which Christ is eaten, the mind is filled with grace, and a pledge of future glory is given to us." (1)
Both Sacrifice and Sacrament Highlighted
5These words highlight both the sacrifice, which pertains to the essence of the Mass that is celebrated daily, and the sacrament in which those who participate in it through holy Communion eat the flesh of Christ and drink the blood of Christ, and thus receive grace, which is the beginning of eternal life, and the "medicine of immortality" according to Our Lord's words: "The man who eats my flesh and drinks my blood enjoys eternal life, and I will raise him up on the last day." (2)
Restoration of Liturgy Linked to Eucharistic Devotion
6And so We earnestly hope that the restoration of the sacred liturgy will produce abundant fruits in the form of Eucharistic devotion, so that the Holy Church may, with this salvific sign of piety raised on high, make daily progress toward the full achievement of unity, (3) inviting all Christians to a unity of faith and love and drawing them to it gently, through the action of divine grace.
7We seem to have a preview of these fruits and a first taste of them in the outpouring of joy and eagerness that has marked the reception the sons of the Catholic Church have accorded to the Constitution on the Sacred Liturgy and to the restoration of the liturgy; and we find these fruits too in the large number of carefully-edited publications that make it their purpose to go into the doctrine of the Holy Eucharist more profoundly and to come to a more fruitful understanding of it, especially in terms of its relationship to the mystery of the Church.
8All of this brings Us deep consolation and joy. And it gives Us great pleasure to inform you of this, Venerable Brothers, so that you may join with Us in giving thanks to God, the bestower of all gifts, who rules the Church and makes her grow in virtue through His Spirit.