[Question:]{.underline} What is the origin of the expression Mysterium fidei found in the consecration of the Precious Blood at the traditional Mass?
[Answer:]{.underline} The interest of this question lies in the fact that this sacred expression cannot be found in the four texts that describe the institution of the Blessed Eucharist, found in the three synoptic Gospels and in St. Paul’s first letter to the Corinthians, nor is it to be found in the words of consecration of the sacred liturgies in the eastern rites.
St. Thomas Aquinas explains the absence of this expression from these four accounts by pointing out that none of these sacred authors intended to write down the form of the sacraments, which were kept hidden in the early Church (IIIa, 78, 3, Ad 9), which is supported by the fact that none of these sources contains the complete form for the consecration of the Holy Eucharist, as found in the traditional Mass. He goes on further to explain that these words — the mystery of faith — are of divine Tradition, being passed on to the Church through the Apostles.
However, this being said, it is clear that these words are not necessary for the validity of the consecration of the chalice. For in the first centuries of the Church, they were not said by the consecrating priest, but were rather an exclamation made by the assistant deacon, to bring the attention of the faithful to the transubstantiation, the greatest of all mysteries and the summary of our Faith. This is confirmed by the fact that, although most ancient, they exist only in the Roman rite.
It does not follow, however, that they are optional, or that the most ancient Tradition of the Church can be abandoned and these words eliminated. They are, in fact, a recognition of the most sublime reality, the highest and most sacred action of which man can be the instrument, the acknowledgment that God alone can perform this miracle upon which our eternal salvation depends. This is how Father Gihr, in The Holy Sacrifice of the Mass (p. 641) describes these words:
“The exclamatory phrase in the middle — the mystery of faith — indicates the unsearchable depth and obscurity of the Eucharistic Sacrifice. That the God-Man did shed His blood for us on the Cross, and that He again sheds it for us in a mystical manner on the altar — is an adorable divine achievement which includes in itself the sum of the most unheard-of wonders, all of which can be acknowledged and believed as true only in the light and the power of faith. Christ’s sacrificial blood in the chalice is a mystery of faith in the fullest sense of the term.”
It is consequently greatly to be regretted that the Novus Ordo Mass has eliminated this expression of Faith, as so much that pertains to the divine action in the propitiatory sacrifice of the altar. It is yet another way in which it undermines the living and profession of the true Catholic Faith.
Answered by Father Peter Scott, SSPX.