1. The Traditional View
For centuries, going back into the mists of time, the priest has said the words “Mysterium fidei” in the midst of the words of consecration whispered over the chalice. These words powerfully evoke the irruption or inbreaking of God into our midst in this unfathomable Sacrament. The consecration of the wine completes the signification of the sacrifice of the Cross, the moment when our High Priest obtained for us eternal redemption (cf. Heb 9:12), the re-presentation of which, together with the application of its fruits, is the very purpose of the Mass.
On November 29, 1202, Pope Innocent III sent a letter Cum Marthae circa to Archbishop John of Lyon—a letter always included in Denzinger—in which he wrote:
You have asked who has added to the words of the formula used by Christ himself when he transubstantiated the bread and wine into his Body and Blood the words that are found in the Canon of the Mass generally used by the Church, but that none of the evangelists has recorded… [namely] the words ‘Mystery of faith’ inserted into the words of Christ… Surely there are many words and deeds of the Lord that have been omitted in the Gospels; of these we read that the apostles have supplemented them by their words and expressed them in their actions… Yet, the expression ‘Mystery of faith’ is used, because here what is believed differs from what is seen, and what is seen differs from what is believed. For what is seen is the appearance of bread and wine, and what is believed is the reality of the flesh and blood of Christ and the power of unity and love.
The pope’s answer amounts to this: there are many things Christ gave to the Apostles to hand down that are not recorded in Scripture, and this could well be one of them. Writing only about seventy years later, St. Thomas Aquinas turns the Archbishop’s question into the ninth objection against the fittingness of the words of consecration of the wine:
Further, the words whereby this sacrament is consecrated draw their efficacy from Christ’s institution. But no Evangelist narrates that Christ spoke all these words. Therefore this is not an appropriate form for the consecration of the wine.
He responds to this objection:
The Evangelists did not intend to hand down the forms of the sacraments, which in the primitive Church had to be kept concealed, as Dionysius observes at the close of his book On the Ecclesiastical Hierarchy; their object was to write the story of Christ. Nevertheless nearly all these words can be culled from various passages of the Scriptures. Because the words, “This is the chalice,” are found in Luke 22:20, and 1 Corinthians 11:25, while Matthew says in 26:28: “This is My blood of the New Testament, which shall be shed for many unto the remission of sins.” The words added, namely, “eternal” and “mystery of faith,” were handed down to the Church by the apostles, who received them from Our Lord, according to 1 Corinthians 11:23: “I have received of the Lord that which also I delivered unto you.”
St. Thomas could have noted that the first Epistle to St. Timothy includes the expression “holding the mystery of faith in a pure conscience” (1 Tm 3:9). Later, in his treatment of the exact wording of the formulas of consecration, Aquinas reiterates that such liturgical details were deliberately hidden in the early Church; Scripture does not have as its purpose the revelation of the precise manner in which sacramental mysteries are to be celebrated.
2. The Phrase’s Antiquity and Obscurity
Even the great demythologizer of twentieth-century liturgical scholarship, Fr. Josef Jungmann, SJ, does not attempt to dismiss or deconstruct what he calls “the enigmatic words”:
The phrase is found inserted in the earliest texts of the sacramentaries, and mentioned even in the seventh century. It is missing only in some later sources. Regarding the meaning of the words mysterium fidei, there is absolutely no agreement. A distant parallel is to be found in the Apostolic Constitutions, where our Lord is made to say at the consecration of the bread: “This is the mystery of the New Testament, take of it, eat, it is My Body.” Just as here the mysterium is referred to the bread in the form of a predicate, so in the canon of our Mass it is referred to the chalice in the form of an apposition…. Mysterium fidei is an independent expansion, superadded to the whole self-sufficient complex that precedes.
What is meant by the words mysterium fidei? Christian antiquity would not have referred them so much to the obscurity of what is here hidden from the senses, but accessible (in part) only to (subjective) faith. Rather it would have taken them as a reference to the grace-laden sacramentum in which the entire (objective) faith, the whole divine order of salvation, is comprised. The chalice of the New Testament is the life-giving symbol of truth, the sanctuary of our belief. How or when this insertion was made, or what external event occasioned it, cannot readily be ascertained.
Several points are worth underlining. This phrase appears in all the oldest sources of the Mass we have, which suggests a great antiquity for its origin. The critical edition of the Canon of the Mass, published by Brepols in the Corpus Orationum series, shows no variation whatsoever of the position of the mysterium fidei. The Roman text is cited in over fifty manuscripts of various ages and origins, with no significant variations. The Ambrosian text, which is the product of a Romanization of the Ambrosian Rite effected in the Carolingian era, has only five manuscripts—but they have it in the same place as well.
The oddness of such an insertion, and the fact that it would be so jealously guarded and passed on, implies that it was considered not an incidental feature of the rite but something that pertained to the essence of the rite of Rome. While we might disagree with Jungmann’s subtle dig at Innocent III’s interpretation, the notion that the “mysterium fidei” points to nothing less than “the entire objective faith” of the Church, “the whole divine order of salvation,” as localized (so to speak) in the symbol of the chalice and its precious content, is an impressive one. The axis of reality runs through that vessel tilted on the altar.
Jungmann’s account, together with the paleographical records, brings strongly to the fore the basic problem that faces liturgical historians when they cannot know with certainty the origin of a particular custom. In such circumstances it is impossible to exclude the hypothesis that it is of apostolic institution or subapostolic institution in Rome. If even the most rigorous scholarship cannot detect a particular moment in history when the words mysterium fidei were added for the first time, and if we have a monolithic witness of extant manuscripts, is it not far better—indeed, is it not a solemn obligation of reverence for the most sacred things we have in our possession—to preserve the formula exactly as it has been handed down? Doing otherwise would surely risk profanation. This, indeed, would have been both the hypothesis and the attitude of all Catholics until the 20th century.
3. A Campaign to Remove the Phrase from Office
In an act of astonishing hubris, this phrase was removed from its immemorial place and turned into the prompt for a “memorial acclamation” that had never existed in the Roman rite before. What had been a secret and sublime acknowledgment of salvation—hidden, like the Christian, with Christ in God (cf. Col 3:3)—became an extroverted announcement to the public, for the sake of “participation” reductively understood as saying and doing things. How exactly did this take place, and why?
Around the time of the Second Vatican Council, liturgical surgeons had been itching to ply their scalpels on the Roman Canon, as soon as authority would permit them to remedy its “defects.” In a book chapter pompously called “The Principal Merits and Defects of the Present Roman Canon,” Cipriano Vaggagini, OSB, held forth in 1966:
The third important defect in the way it [the Canon] relates the instituting of the Eucharist is the insertion of the phrase mysterium fidei in the midst of the words said over the chalice. This has no parallel in any other liturgy, and within the Roman rite itself its origin in uncertain and its meaning debatable. However, it is obvious that in its present form at least the insertion mysterium fidei serves to break up and interrupt the words of institution.
Bugnini tells us in his mighty tome The Reform of the Liturgy that Vaggagini, “in three months of intensive work in the library of the Abbey of Mont-César (Louvain) during the summer of 1966…composed two models of new Eucharistic Prayers, which he presented to the group for discussion.” Subsequent discussion concurred that something had to be done about that pesky mysterium fidei:
The addition “the mystery of faith” in the formula for the consecration of the wine in the Roman Canon: is not biblical; occurs only in the Roman Canon; is of uncertain origin and meaning. The experts themselves disagree on the precise sense of the words. In fact, some of them assign the phrase a quite dangerous meaning, since they translate it as ‘‘a sign for our faith’’; interrupts the sentence and makes difficult both its understanding and its translation. The French, for example, have been forced to repeat the word “blood” three times: “This is the cup of my blood, the blood of the new covenant, mystery of faith, blood shed…” The same is true to a greater or lesser extent in the other languages. Once again, many bishops and pastors have asked that in the new anaphoras the addition “mystery of faith” be dropped. All this explains the course followed in the new anaphoras with regard to the words of consecration.
Moreover, it was felt to be desirable that there be some “acclamation of the congregation after the consecration and elevation of the chalice”; and why?
The practice is native to the Eastern Churches, but it seems appropriate to accept it into the Roman tradition as a way of increasing the active participation of the congregation. Regarding the exact form of the acclamation, the rubric says that it can use “these or similar words approved by the territorial authorities.” Since the acclamations are to be said, or even sung, by the congregation, it is necessary to leave enough freedom for them to be adapted to the requirements of the various languages and musical genres.
At this point in the process, then, the idea was to remove the words “mysterium fidei” altogether and simply have an acclamation follow upon the elevation of the chalice.
On June 26, 1967, Cardinal Ottaviani, in his capacity as head of the Congregation for the Doctrine of the Faith sent a letter to Annibale Bugnini, expressing the changes that the Congregation would prefer to see made to the four Eucharistic Prayers that had been submitted for doctrinal review. Those who see Ottaviani as a hero for placing his name on the Short Critical Study two years later may be surprised and disappointed to see how readily he was rolling along with the Consilium’s plan:
About the omission of the parenthesis (inciso) “mysterium fidei”: affirmative.
With regard to the “acclamation” immediately after the elevation, “Mortem tuam...,” we would prefer a text that expresses more clearly an act of faith, and thus replaces the disappeared “mysterium fidei”—[a phrase] certainly inopportune for the position in which it found itself, but obviously indicated as a call to awaken faith at that solemn moment. The evangelical phrase “Deus meus et Dominus meus” has been suggested.
At the famous Synod of Bishops in October 1967—the participants of which counted as the first significant body of “outsiders” to be shown the Missa normativa or rough draft of that which Paul VI would later call the Novus Ordo Missae and then asked to vote on it and contribute comments—the following question, among others, was put to the Synod Fathers, as reported by Bugnini:
Should the words “mysterium fidei” be removed from the formula for the consecration of the wine? Of the 183 voting, 93 said yes, 48 no, and 42 yes with qualifications. In substance, the qualifications were these: 1) The words should also be omitted in the Roman Canon. 2) The words should not completely disappear from the liturgy but should be used as an acclamation after the consecration or in some other formula.
If we take the no votes and the qualified yes (placet iuxta modum) votes together, we see that the majority unqualifiedly in favor of removal was narrow: 93 to 90. Nevertheless, it seems that the attitude of most was like that of Ottaviani: why not take advantage of the general upheaval and turn this phrase into a vehicle of participation?
One cannot escape the impression of people “making things up as they went along,” bereft of any real reverence for tradition or fear of the Lord.
4. Paul VI Insists on Repurposing the Phrase
The issue remained controversial within the Consilium. As Bugnini narrates, the topic came up again at the tenth general meeting (April 23–30, 1968), which met to discuss the six changes on which Paul VI had had the temerity (in the experts’ view) to insist in regard to the Missa normativa. “The whole matter caused some dismay, since the Pope seemed to be limiting the Consilium’s freedom of research by using his authority to impose solutions.” The special subcommittee created to deal with the problem included, among others, Rembert Weakland, Joseph Gélineau, and Cipriano Vaggagini.
In regard to our present topic, Paul VI—not surprisingly for a pope who had chosen the title Mysterium Fidei for his great encyclical of 1965 defending transubstantiation and condemning certain heretical tendencies in Eucharistic theology—disliked the idea of going straight from the elevation to the acclamation and had requested specifically that “the words ‘mysterium fidei’ are [still] to be spoken by the priest before the acclamation of the congregation.” Bugnini relates:
What were the difficulties raised by the study group against the adoption of what the Pope wanted?... Mystery of faith. If the words were said by the celebrant before the acclamation of the congregation, (a) this would be an innovation not found in the liturgical tradition; (b) it would alter the structure of the Canon at an important moment; (c) it would change the meaning of the words in question, since they are no longer connected with the consecration of the chalice. If the words are to be kept, the report said, they should be connected either with the formula of consecration of the wine or with the acclamation.
In the end, Paul VI prevailed. We are therefore not surprised to find this change and its pastoral “benefit” announced in the Apostolic Constitution Missale Romanum of April 3, 1969. The irony of its immediate context, however, deserves close attention:
As to the words Mysterium fidei, removed from the context of the words of Christ our Lord and spoken by the Priest, these open the way, as it were, to the acclamation of the faithful.
Regarding the Order of Mass, “the rites have been simplified, due care being taken to preserve their substance.”… Furthermore, “there have been restored…in accordance with the ancient norm of the holy Fathers, various elements which have suffered injury through accidents of history.”
Unlike the justification for “restoring” the “responsorial psalm,” which is based on false antiquarianism and a reductive theory of participation, here the pope offers no explanation except that it shall “open the way, as it were, to the acclamation of the faithful.” Yet this change to the venerable Roman Canon (and then replicated in all the neo-anaphoras) cannot have been done with “due care” to “preserve [the] substance” of the rites, as the ironic reference to “restoring elements that have suffered injury through accidents of history, in accordance with the ancient norm of the holy fathers” indicates.
In regard to the mysterium fidei, the ancient norm was expressly violated; the only injury inflicted was of the Consilium’s design. It was rather through the accidents of the postconciliar liturgical reform that the Roman rite suffered injury.
5. Cardinals and Theologians Protest
Once the approved text of the Novus Ordo became available in 1969, Cardinal Ottaviani seems to have changed his mind sufficiently to be willing to sign his name, alongside Cardinal Bacci’s, to the Short Critical Study of the New Order of Mass, in which we find the following critique by “a group of Roman theologians”:
The old formula for the Consecration was a sacramental formula, properly speaking, and not merely narrative… The Scripture text was not used word-for-word as the formula for the Consecration. St. Paul’s expression the mystery of faith was inserted into the text as an immediate expression of the priest’s faith in the mystery which the Church makes real through the hierarchical priesthood.
I find this an excellent insight into the ascetical benefit for the priest: the mysterium fidei in the midst of the consecration of the Precious Blood is a “speed bump” that reminds him to be ever more aware of the awesome reality of what he is doing before God and for the people—no empty commemoration, but the making present of the objective Mystery “which hath been hidden from ages and generations, but now is manifested to his saints” (Col 1:26). The Short Critical Study continues:
Furthermore, the people’s Memorial Acclamation which immediately follows the Consecration—We proclaim your death, O Lord...until you come—introduces the same ambiguity about the Real Presence under the guise of an allusion to the Last Judgment. Without so much as a pause, the people proclaim their expectation of Christ at the end of time just at the moment when He is substantially present on the altar—as if Christ’s real coming will occur only at the end of time rather than there on the altar itself. The second optional Memorial Acclamation brings this out even more strongly: “When we eat this bread and drink this cup, we proclaim your death, Lord Jesus, until you come in glory.” The juxtaposition of entirely different realities—immolation and eating, the Real Presence and Christ’s Second Coming—brings ambiguity to a new height.
Even if the Short Study could have expressed this criticism more accurately (the language is too loose), it is unquestionably right to say that moving a phrase of such antiquity, theological density, and liturgical significance, and introducing acclamations that immediately shift attention to the eschatological banquet, cannot but modify the understanding of the intended action.
A response printed in 1969 in Notitiae, the official journal of the Consilium (and later of the Congregation for Divine Worship that took its place), made it clear that the transplantation of the mysterium fidei fundamentally altered its character.
Query: When no member of the faithful is present who can make the acclamation after the consecration, should the priest say “The mystery of faith”?
Response: In the negative. The words The mystery of faith, which have been taken from the context of the words of the Lord and placed after the consecration, “serve as an introduction to the acclamation of the faithful” (cf. Const. Missale Romanum). When, however, in particular circumstances no one is able to respond, the priest omits these words, as is done in a Mass which, out of grave necessity, is celebrated without any minister, in which the greetings and blessing at the end of Mass are omitted (Inst. gen., n. 211). The same holds true for a concelebration of priests in which no member of the faithful is present.
In other words, the phrase has been transformed from a component of the formula of consecration, with a polysemous density of theological meaning accompanied by an ascetical function for the priest himself, into a congregationally-directed prompt. Without the congregation, the mysterium fidei, in a sense, ceases to exist. This Notitiae response testifies to the phrase’s total severance from tradition.
6. Larger Implications of the Change
The removal of mysterium fidei from its hallowed position to a new position with a new function had at least a quadruple effect.
First, it ratified once again, and in a rather dramatic way, the widespread tendency of modern liturgical scholars—not only Jungmann, who, as we have seen, is sound on the mysterium fidei, but even such eminent figures as Adrian Fortescue and Cardinal Schuster—to assume that long-standing parts of the text of the Canon and of many other parts of the liturgy are mere historical accidents, or more likely, mistakes introduced by ignoramuses. It slapped the Vaggaginis of the world on the back and said: “Well done, thou critic of good and faithful servants!”
Second, it cancels out or at least brackets in suspicion the pious belief in the derivation of the formula from apostolic tradition and the medieval reception of the same tradition, to which the exceptionless liturgical witness offers a support greater than any doubt scholarship can induce. In this way, it made its own contribution to the general undermining of piety towards inherited liturgical forms, perhaps the most execrable fallout of the reform.
Third, by audaciously modifying the formula used at the most solemn moment of the Holy Sacrifice, the change sent the clear message—clearer even than the insertion of the name of St. Joseph into the Canon in 1962, which was its precursor—that the liturgical changes undertaken in the sixties constitute a revolution, not a reform. Certain changes cannot plausibly be seen as refinements or adjustments that remain in continuity with tradition; they are, quite simply, ruptures. The sooner we recognize this, the sooner we can put aside the will-o’-the-wisp of “the Reform of the Reform” and resume lost continuity where it was broken off.
Lastly, on a wholly practical level, there is the sheer banality of the fabricated “memorial acclamation” as carried out in practice in the plethora of vernacular versions into which the Roman rite has been shattered. When the Eucharistic Prayer is spoken aloud in the vernacular, the atmosphere—which a fortunate ars celebrandi might even have rendered somewhat prayerful—is shattered at its most solemn point by the never quite unanimous muttering of one or another appointed text, led off by the priest in his secondary role of schoolmarm. When the acclamation is sung, the results can be far worse: musicians malnourished on a diet of Haugen-Haas™ seem to fall beneath even their worst efforts when they set the memorial acclamations in treacly tunes with cartoon clichés. The immolation of the Bridegroom is mentally wiped out by a cheap imitation of Broadway.
From a ritual and theological point of view, this acclamation is nothing but an intrusion, an interruption, and an irrelevancy in the flow of the liturgical action, which at that moment concerns offering to the Father the holy Victim, the pure Victim, the spotless Victim, for the salvation of man. Our participation is to adore in silence, uniting ourselves to His sacrifice on the Cross and awaiting His abundant mercy. It is not the mysterium fidei that deserves to be denigrated as a “parenthesis,” but the memorial acclamation, brainchild of Paul VI and the Consilium.
7. As Always, Tradition Is the Way Forward
The mystery of our faith is intimately and intrinsically bound up with hunc praeclarum calicem, “this precious chalice.” The whispered words mysterium fidei stand at the heart of the consecration of the chalice. Their removal is emblematic of what was done to the liturgy as a whole, when the heart of so many rites was ripped out of them. Even if the words mysterium fidei are not necessary for signifying transubstantiation (and thus, the consecration can be “effective,” and the Mass “valid,” without them), the removal of mysterium fidei from its age-old position exudes the attitude: nothing is sacred.
Psalm 15 uses the cup or chalice as a symbol of God’s generous provision to His people: “The Lord is the portion of my inheritance and of my cup: it is thou that wilt restore my inheritance to me” (Ps 15:5). This verse reminds us of the nature of our liturgical inheritance. It is not the fallout of meandering chance and merely human intentions, subject to perpetual revision, but a living tradition that begins in the Logos of God and culminates in the Logos-made-flesh, our eternal High Priest who guides His Church by the gift of His Spirit. The attitude we are supposed to have towards our inheritance—that which “falls to our lot”—is captured in the next verse: “The lines are fallen unto me in goodly places: for my inheritance is goodly to me” (Ps 15:6).
These two words, mysterium fidei… That we do not know whence they came, or why they are where they are, imposes an insurmountable limit of humility to our scholarly pride; that we cannot comprehend the full scope of their meaning or sort them into Cartesian “clear and distinct” ideas thwarts the restless vanity of our ambitions, putting us in the place of beggars who look for whatever scraps of insight may fall from our master’s heavenly table. That is what we truly are; this is where we truly belong. “Here is the patience and the faith of the saints… Here is wisdom” (Rev 13:10, 18).
It is still there in the 43rd edition of Denzinger (San Francisco: Ignatius Press, 2012), at n. 782.
Summa theologiae III, qu. 78, art. 3.
 cf. Summa theologiae III, qu. 83, art. 4, ad 2.
 Josef Jungmann, SJ, The Mass of the Roman Rite: Its Origins and Development (Missarum Sollemnia), 2 vols., trans. Francis A. Brunner (Notre Dame, IN: Christian Classics, 2012) 2:199–201.
Tome X (1997), begun by Edmond Eugene Möller and continued by Jean-Marie Clément, OSB, and Bertrandus Coppetiers ‘t Wallant. Within the body of the work, that part of the Canon is Oratio 6265, with three major variants attested: 6265a is the Roman text, 6265b the Ambrosian, and 6265c an anomalous Ambrosian text attested in a single manuscript.
 Cipriano Vaggagini, OSB, The Canon of the Mass and Liturgical Reform, trans. Peter Coughlin (Staten Island, NY: Alba House, 1967; published in Italian in 1966), 104. Vagganini’s assertion that “it has no parallel in any other liturgy,” while true as far as the text goes, is characteristically misleading: no historical Christian rite has ever used the Biblical text strictly and solely as the words of Consecration. In other words, the formulas of consecration recorded in the New Testament are not the exact formulas used in the historic Christian liturgies. These liturgical rites pre-date the biblical texts and reflect particular customs which have their own rationale.
 Annibale Bugnini, The Reform of the Liturgy 1948–1975, trans. Matthew J. O’Connell (Collegeville, MN: The Liturgical Press, 1990), 450. The group was Coetus X, the one to which the Ordo Missae was entrusted.
 Ibid., 454.
 Ibid., 455.
Consistory of Cardinals, May 24, 1976: “usus novi Ordinis Missae” and “Novus Ordo promulgatus est”—“the use of the new Order of Mass”; “the new Order has been promulgated.”
 Bugnini, Reform of the Liturgy, 352.
 Ibid., 370.
 Ibid., 371–72.
The theory propounded by some preconciliar scholars, to the effect that the mysterium fidei originated as something that the deacon said to the people at or just after the Consecration, was already dismissed in 1949 by Jungmann as “poetry, not history”: The Mass of the Roman Rite, 199. This was a book everyone had read at the time.
 Alfredo Cardinal Ottaviani and Antonio Cardinal Bacci, The Ottaviani Intervention: Short Critical Study of the New Order of Mass, trans. Anthony Cekada (West Chester, OH: Philothea Press, 2010), 56; text slightly modified to match English text of memorial acclamation.
 See my article “Why the ‘Reform of the Reform’ Is Doomed,” OnePeterFive, April 22, 2020, https://onepeterfive.com/reform-of-the-reform-doomed/.
 In contrast to nearly every vernacular version I’ve ever heard, the Latin acclamation (Mortem tuam annuntiamus, Domine…) is beautifully set to a classic Gregorian melody. Nevertheless, the beauty of the chant cannot overcome the more profound problems discussed in this article.