The Latin Mass and the Novus Ordo

Among Roman Catholics today, some are devoted to the "Latin Mass," the Roman Missal as it stood before the Second Vatican Council. The ordinary form in Catholic parishes is the missal promulgated by Pope Paul VI in 1969, often called the Novus Ordo ("new order"). In the last twenty years Rome has first widened and then sharply narrowed permission for the older form.

Some Catholics who love the old rite see the Orthodox as natural allies. This article sets out the history from 1570 to 2021 from the Vatican's own documents, then gives the Orthodox view: what Orthodoxy shares with the traditionalist instinct, and why the quarrel between the two Roman missals is not the Orthodox Church's quarrel.

In brief

In 1570 Pope Pius V imposed a single Roman Missal on the Latin Church, sparing rites with two centuries of continuous use. The Second Vatican Council's Sacrosanctum Concilium (1963) asked for a reform of the Mass while saying that Latin was "to be preserved" and that new forms should "grow organically from forms already existing." Paul VI's missal, in force from 30 November 1969, added three new Eucharistic Prayers to the ancient Roman Canon. Two cardinals protested, and in 1988 Archbishop Marcel Lefebvre's consecration of four bishops was called "a schismatic act." Benedict XVI freed the 1962 missal in 2007; Francis in 2021 declared the post-conciliar books "the unique expression" of the Roman rite. The Divine Liturgy also developed over centuries, but by use and reception, not by a commission composing a new rite. Orthodox objections to the Roman Mass in either form concern faith, not age: the Filioque, the Western teaching on consecration and the epiclesis, the bread, and the place of the pope.

Thesis: The Orthodox Church honors the reverence that draws many Catholics to the older Roman rite, but its quarrel with Rome was never about which Roman missal is older; both missals carry the same departures from the faith of the undivided Church, and the remedy is a return to that faith, not a return to 1962.

The Missal of 1570

After the Council of Trent, Pope Pius V issued the bull Quo Primum (14 July 1570) with a revised Roman Missal. It was required throughout the Latin Church unless a church's own rite had been approved by the Apostolic See "at least 200 years ago" or rested on a custom "continuously followed for a period of not less than 200 years." The bull ordered "that nothing must be added to Our recently published Missal, nothing omitted from it, nor anything whatsoever be changed within it."¹ Later popes revised it nonetheless, most recently under John XXIII in 1962, the edition used by those attached to the older form today.

Paul VI himself said the general arrangement of the 1570 missal's prayers went back "in essence, to St. Gregory the Great," and that the Roman Canon "took on an unchangeable form during the fourth and fifth centuries."² The Orthodox Church commemorates St Gregory on 12 March as "Saint Gregory Dialogus, Pope of Rome," and traditionally associates the Liturgy of the Presanctified Gifts with his name (see Who Was Pope Gregory the Great?). The Orthodox question is not whether the Roman rite is ancient but what it came to confess.

The Council and the reform (1963-1970)

Both sides of today's quarrel quote Sacrosanctum Concilium (4 December 1963), so its exact words matter.

• "The rite of the Mass is to be revised in such a way that the intrinsic nature and purpose of its several parts, as also the connection between them, may be more clearly manifested, and that devout and active participation by the faithful may be more easily achieved" (art. 50).
• "Particular law remaining in force, the use of the Latin language is to be preserved in the Latin rites" (art. 36.1), though the mother tongue could be extended (36.2).
• Gregorian chant "should be given pride of place in liturgical services" (art. 116).
• "There must be no innovations unless the good of the Church genuinely and certainly requires them; and care must be taken that any new forms adopted should in some way grow organically from forms already existing" (art. 23).³

Paul VI promulgated the new missal on Holy Thursday, 3 April 1969, to take effect on "November 30th of this year, the first Sunday of Advent." He was candid: "The major innovation concerns the Eucharistic Prayer." Beside the Roman Canon, "we have decided to add three new Canons," and the Sunday readings were set in a three-year cycle.⁴ The new prayers include an explicit invocation of the Holy Spirit placed before the words of institution, in which, says the General Instruction of the Roman Missal, the Church "implores the power of the Holy Spirit that the gifts offered by human hands be consecrated."⁵

{{very-strong: Paul VI's missal, promulgated on 3 April 1969 and in force from 30 November 1969, added three new Eucharistic Prayers to the single Roman Canon; Paul VI himself called the Eucharistic Prayer its "major innovation."}}

Whether the committees went beyond what the Council mandated is the center of the Catholic debate (see Vatican II: Did the Catholic Church Change Its Doctrine?). Catholics must settle it among themselves.

Resistance: Ottaviani and Lefebvre

On 25 September 1969 Cardinal Alfredo Ottaviani, retired head of the doctrinal congregation, and Cardinal Antonio Bacci sent Paul VI a critical study of the new Order of Mass by a group of Roman theologians. Their cover letter said the new rite represented "a striking departure from the Catholic theology of the Mass" as formulated in the twenty-second session of Trent, and that the pastoral reasons offered could not justify "such a grave break."⁶

The most lasting resistance came from Archbishop Marcel Lefebvre and the Society of St Pius X, which he founded at Fribourg in 1970. On 30 June 1988, without papal mandate, he consecrated four priests as bishops: Bernard Fellay, Bernard Tissier de Mallerais, Richard Williamson and Alfonso de Galarreta. John Paul II's letter Ecclesia Dei answered that "this act was one of disobedience to the Roman Pontiff in a very grave matter," implying "the rejection of the Roman primacy," and so "constitutes a schismatic act"; the five incurred excommunication.⁷ Benedict XVI lifted the four bishops' excommunications in January 2009 but wrote that "the Society has no canonical status in the Church" and its ministers "do not legitimately exercise any ministry in the Church."⁸ Rome's judgment rested on the pope's authority rather than on Latin or rubrics.

Summorum Pontificum (2007) and Traditionis Custodes (2021)

Rome had allowed the 1962 missal by indult in 1984. Benedict XVI's Summorum Pontificum (7 July 2007, in force 14 September) declared Paul VI's missal "the ordinary expression of the lex orandi" and the 1962 missal, "never abrogated," "an extraordinary expression of the same lex orandi": "two usages of the one Roman rite."⁹ Benedict's accompanying letter said: "In the history of the liturgy there is growth and progress, but no rupture. What earlier generations held as sacred, remains sacred and great for us too, and it cannot be all of a sudden entirely forbidden or even considered harmful."¹⁰

Francis reversed course. Traditionis Custodes (16 July 2021) states: "The liturgical books promulgated by Saint Paul VI and Saint John Paul II, in conformity with the decrees of Vatican Council II, are the unique expression of the lex orandi of the Roman Rite." Only the bishop may authorize the 1962 missal; he must ensure such groups "do not deny the validity and the legitimacy of the liturgical reform," and not place them "in the parochial churches."¹¹ Francis wrote that Benedict's generosity "was exploited to widen the gaps, reinforce the divergences, and encourage disagreements that injure the Church," and cited a precedent: "after the Council of Trent, St. Pius V also abrogated all the rites that could not claim a proven antiquity."¹²

Two popes have given opposite answers on the same rite within fourteen years. Which judged more wisely is a Catholic question, and this site takes no side in it.

How the Orthodox see the quarrel

The Divine Liturgy also grew, but it grew

Orthodox apologists sometimes say the Divine Liturgy never changed. Orthodox scholars do not. Fr Thomas Hopko's OCA catechism says the liturgies of St John Chrysostom and St Basil "probably received their present form after the ninth century. It is not the case that they were written exactly as they now stand by the saints whose names they carry," though "the eucharistic prayers of each of these liturgies were formulated as early as the fourth and fifth centuries." The preparation of the gifts, in its present form, probably dates from the fourteenth century.¹³ Robert Taft, the Jesuit historian of the Byzantine rite, notes that the Cherubic Hymn was "introduced into the liturgy under Justin II in 573-574," and that the rubric book of Philotheos Kokkinos, written before 1347 on Mount Athos, "eventually became normative throughout the Byzantine Church outside Italy."¹⁴

Orthodoxy has also known the pain of reform from above. In 1653 Patriarch Nikon of Moscow "began to revise the Russian Orthodox liturgy and service books to make them conform to Greek practice," including the sign of the cross. Those who refused, the Old Believers, were anathematized in 1667; the Russian Church lifted those anathemas only in 1971, and the division has not healed.¹⁵

Even so, the histories differ in kind. Nikon sought conformity with the Greek usage of his day; he composed no new anaphoras. Nothing in Orthodox history matches a commission composing new Eucharistic Prayers and a new order of service, imposed on a whole Church within a few years. Sacrosanctum Concilium itself asked that new forms "grow organically," and the Orthodox instinct agrees with St Paul: "For I received from the Lord that which I also delivered to you" (1 Corinthians 11:23, NKJV).¹⁶

{{strong: The Byzantine Divine Liturgy reached its present form through gradual growth over many centuries, without a commission composing a replacement rite; the chief exception, Nikon's seventeenth-century correction of Russian books toward existing Greek usage, caused a lasting schism.}}

The epiclesis

In the Orthodox anaphora, after the words of institution and the offering, the priest prays: "Send down Your Holy Spirit upon us and upon these gifts lying here before us," and, blessing the gifts, asks that they become the Body and Blood of Christ, "Changing them by Your Holy Spirit."¹⁷ Hopko notes that this prayer "is considered by the Orthodox to be an essential part of the Divine Liturgy" (see What Happens During the Divine Liturgy?).¹⁸

The Roman Canon of the 1570 and 1962 missals has no explicit invocation of the Spirit after the words of institution. The Catholic liturgist Adrian Fortescue argued in 1909 and 1910 that "The Roman Rite too at one time had an Epiklesis after the words of Institution," later "omitted or mutilated" into the prayer Supplices te rogamus.¹⁹ At Florence (1439), by Fortescue's account, the Greek delegates held that the Supplices "is a true Epiklesis having the same effect as theirs." The council nonetheless taught, in its decree for the Armenians, that "The form of this sacrament are the words of the Saviour," and St Mark of Ephesus answered that the gifts are sanctified "not only by the sound of the Lord's words" but also by the prayer that follows.²⁰

The Catechism of the Catholic Church now speaks of "the power of the words and the action of Christ, and the power of the Holy Spirit," yet still places the change "In the institution narrative," and notes that "some liturgical traditions put the epiclesis after the anamnesis."²¹ Florence's teaching that the words of Christ are the form that consecrates has not been withdrawn, and in the new prayers the invocation stands before those words. The Orthodox Church rejects that narrowing. The Eucharist is the work of the whole Trinity: the Church offers to the Father, remembering the Son's words and sacrifice, and asks the Father to send the Holy Spirit, who changes the gifts into the Body and Blood of Christ. Neither Roman missal resolves this: the older lacks the explicit prayer, and the newer keeps the Latin theology of consecration. See also Catholic and Orthodox Views of the Eucharist and Is the Mass a Sacrifice?

The bread

The Orthodox Church offers leavened bread; the Latin Church uses unleavened hosts in both missals. A Catholic reference work admits that "History does not establish conclusively what the practice of the Apostles and their successors was."²² In 1053 Leo, metropolitan of Ohrid, complained of Latin customs, "especially fasting on Saturday and the use of azyme (unleavened) bread for the Holy Eucharist," and the quarrel fed the crisis of 1054, with harsh words on both sides.²³ Florence declared both breads valid,²⁴ but the Orthodox Church rejected that council (see The Council of Florence) and keeps the bread it received. The azymes remain a real difference, though not the deepest one.

The Creed

Both Roman missals confess that the Holy Spirit proceeds "from the Father and the Son." The Catechism grants that "The affirmation of the filioque does not appear in the Creed confessed in 381 at Constantinople," that it was "gradually admitted into the Latin liturgy (between the eighth and eleventh centuries)," and that it "constitutes moreover, even today, a point of disagreement with the Orthodox Churches."²⁵ The Catholic Encyclopedia records that Pope Leo III advised leaving it out of the Creed, and that its use in Rome is usually dated to Benedict VIII (1014-15).²⁶

{{very-strong: The Creed in both the 1962 and the post-1969 Roman missals contains the Filioque, which the Creed of 381 does not contain.}}

The Orthodox verdict is firm. The Holy Spirit proceeds from the Father alone, the one source in the Trinity, as the Creed of 381 confesses; the addition is an error about God, made to the common Creed without an ecumenical council. A Mass that sings an altered Creed is not traditional in the Orthodox sense (see The Filioque).

The pope

The Roman Canon's intercession, the Te igitur, opens with a prayer for the pope.²⁷ But the history above shows the papacy's place in the Latin Church: the standing of the oldest Western rite depends on each pope's decree. The Orthodox Church holds papal supremacy and infallibility to be errors. Its rites are guarded by councils and bishops in communion with one another, and by the faithful who pray them.

Why Orthodox Christians are not "traditionalist Catholics"

There is real common ground: worship should be received, not invented; chant, silence and the sense of sacrifice belong to it; and a rite cannot be remade in a few years without wounding the faithful. Benedict's words, "What earlier generations held as sacred, remains sacred and great for us too," would sound natural in an Orthodox parish.

But Orthodoxy is not an older form of Roman Catholicism. The 1962 missal already had the Filioque, the Western account of consecration and the commemoration of a pope whose claims the Orthodox reject. The Catholic debate also runs inside the papal framework, each side resting on papal acts. The Orthodox appeal is to the faith of the seven Ecumenical Councils and the Fathers, kept in the Orthodox Church, the One, Holy, Catholic and Apostolic Church of the Creed.

The Orthodox Church does not reject Western liturgy as such. The pre-schism West was Orthodox, and a few Orthodox parishes today, such as those of the Antiochian Archdiocese's Western Rite Vicariate in North America, celebrate a Rite of St Gregory based on the historic Roman Mass (see Western Rite Orthodoxy). Their text confesses that the Holy Spirit "proceedeth from the Father" and, after the words of institution, prays: "And we beseech thee, O Lord, to send down thy Holy Spirit upon these offerings."²⁸ What Orthodoxy asks of a Western rite is the Orthodox faith. That is also why Orthodox and Catholics do not share Communion (see Why Can't Non-Orthodox Christians Receive Communion in an Orthodox Church?).

Objections and replies

"The Orthodox liturgy changed too, so Orthodox critics have no standing."

It did change, and Orthodox writers should say so. The difference is between growth by use, received by the whole Church over centuries, and a new order composed by a commission and promulgated by one man. In any case the Orthodox objection rests on points of faith that the 1962 missal shares, not on the Novus Ordo's novelty.

"The Roman Canon is as old as the Byzantine anaphoras, and it has an epiclesis."

Its core is ancient, as Paul VI said, and some see an epiclesis in the Quam oblationem or the Supplices, as the Greeks at Florence did. But age does not settle doctrine. The Filioque in the Creed and the doctrine that the words alone consecrate are later Western developments, whatever the age of the surrounding prayers.

What we can say confidently

• Quo Primum (1570) imposed one Roman Missal; later popes revised it up to 1962.
• Sacrosanctum Concilium asked for reform but also that Latin "be preserved" and that new forms "grow organically."
• Paul VI's missal (1969) added three new Eucharistic Prayers; Ottaviani and Bacci protested; Lefebvre's 1988 consecrations were judged a schismatic act.
• Summorum Pontificum (2007) and Traditionis Custodes (2021) took opposite approaches to the 1962 missal.
• The Divine Liturgy developed gradually over many centuries and keeps an explicit epiclesis after the words of institution.
• Both Roman missals contain the Filioque and rest on the Latin theology of consecration, which the Orthodox Church rejects.

What remains disputed

• {{debated: Whether the early Roman Canon had an invocation of the Holy Spirit after the words of institution that was later reduced to the Supplices te rogamus prayer, as Fortescue argued.}}
• How far the Novus Ordo carried out, or went beyond, what the Council mandated; this is an intra-Catholic debate.
• Whether Christ used leavened or unleavened bread at the Last Supper, which depends on how the Gospel chronologies are reconciled.
• How much of the anaphoras bearing their names St Basil and St John Chrysostom composed themselves.
• What Ottaviani finally thought: a letter over his signature dated 17 February 1970 regretted the publication of his 1969 letter; the traditionalist Jean Madiran claimed the blind cardinal signed it unread, an unproven charge.²⁹

Conclusion

The argument over the Latin Mass is a family argument within the Roman Church, and the Orthodox should treat it with charity and restraint.

The Orthodox Church can still say plainly what it has always said. Tradition is the faith once delivered to the saints, prayed in the Church, and no single century's missal can stand in for it: the Creed as the Fathers wrote it, the Father who sends the Holy Spirit upon the gifts, and the Body and Blood of the risen Christ given for the life of the world. Catholics drawn to the old rite by a hunger for that continuity are welcome to come and see the Divine Liturgy, where the Church still prays, "Send down Your Holy Spirit upon us and upon these gifts lying here before us."

Notes

1. Pius V, Quo Primum (14 July 1570), English translation at Papal Encyclicals Online, https://www.papalencyclicals.net/pius05/p5quopri.htm.
2. Paul VI, Apostolic Constitution Missale Romanum (3 April 1969), https://www.vatican.va/content/paul-vi/en/apost_constitutions/documents/hf_p-vi_apc_19690403_missale-romanum.html. On the Orthodox commemoration: Orthodox Church in America, "Saint Gregory Dialogus, Pope of Rome" (12 March), https://www.oca.org/saints/lives/2020/03/12/100789-saint-gregory-dialogus-pope-of-rome.
3. Second Vatican Council, Sacrosanctum Concilium (4 December 1963), arts. 23, 36, 50, 54, 116, https://www.vatican.va/archive/hist_councils/ii_vatican_council/documents/vat-ii_const_19631204_sacrosanctum-concilium_en.html.
4. Paul VI, Missale Romanum (see note 2).
5. General Instruction of the Roman Missal (2002), no. 79c; see also no. 179, https://www.vatican.va/roman_curia/congregations/ccdds/documents/rc_con_ccdds_doc_20030317_ordinamento-messale_en.html.
6. Cardinals Alfredo Ottaviani and Antonio Bacci, letter to Paul VI (25 September 1969), in the translation at the Internet Modern History Sourcebook, Fordham University, https://sourcebooks.web.fordham.edu/mod/1969ottoviani.asp; compared with the translation published by the Society of St Pius X, https://dickinson.tx.sspx.org/en/letter-cardinal-ottaviani-pope-paul-vi-30144.
7. John Paul II, Apostolic Letter Ecclesia Dei (2 July 1988), nos. 1, 3, https://www.vatican.va/content/john-paul-ii/en/motu_proprio/documents/hf_jp-ii_motu-proprio_02071988_ecclesia-dei.html. On the Society's founding: decree of erection by François Charrière, Bishop of Lausanne, Geneva and Fribourg (1 November 1970), in "SSPX's founding documents," https://fsspx.ie/en/sspxs-founding-documents.
8. Benedict XVI, Letter to the Bishops concerning the remission of the excommunication of the four bishops consecrated by Archbishop Lefebvre (10 March 2009), https://www.vatican.va/content/benedict-xvi/en/letters/2009/documents/hf_ben-xvi_let_20090310_remissione-scomunica.html.
9. Benedict XVI, Motu Proprio Summorum Pontificum (7 July 2007), arts. 1, 2, 5, 12, https://www.vatican.va/content/benedict-xvi/en/motu_proprio/documents/hf_ben-xvi_motu-proprio_20070707_summorum-pontificum.html.
10. Benedict XVI, Letter to the Bishops accompanying Summorum Pontificum (7 July 2007), https://www.vatican.va/content/benedict-xvi/en/letters/2007/documents/hf_ben-xvi_let_20070707_lettera-vescovi.html.
11. Francis, Motu Proprio Traditionis Custodes (16 July 2021), arts. 1-3, https://www.vatican.va/content/francesco/en/motu_proprio/documents/20210716-motu-proprio-traditionis-custodes.html.
12. Francis, Letter to the Bishops accompanying Traditionis Custodes (16 July 2021), https://www.vatican.va/content/francesco/en/letters/2021/documents/20210716-lettera-vescovi-liturgia.html.
13. Thomas Hopko, The Orthodox Faith, vol. 2, Worship, "The Divine Liturgy" and "Prothesis," Orthodox Church in America, https://www.oca.org/orthodoxy/the-orthodox-faith/worship/the-divine-liturgy/the-divine-liturgy and https://www.oca.org/orthodoxy/the-orthodox-faith/worship/the-divine-liturgy/prothesis.
14. Robert Taft, "The Liturgy of the Great Church: An Initial Synthesis of Structure and Interpretation on the Eve of Iconoclasm," Dumbarton Oaks Papers 34/35 (1980-81): 45-75, at 45-46 and n. 6, 54, https://archive.org/details/DOP34-35_04_Taft.
15. J. Clay, "Old Believers," Encyclopedia of World Cultures, via Encyclopedia.com, https://www.encyclopedia.com/philosophy-and-religion/christianity/christianity-general/old-believers; Metropolitan Hilarion (Alfeyev), interview with Kommersant (2021), Department for External Church Relations, https://mospat.ru/en/news/87823.
16. Sacrosanctum Concilium 23 (see note 3); 1 Corinthians 11:23, NKJV, https://www.biblegateway.com/passage/?search=1+Corinthians+11%3A23&version=NKJV.
17. "The Divine Liturgy of St. John Chrysostom," English text, American Carpatho-Russian Orthodox Diocese of North America, https://www.acrod.org/prayercorner/liturgicaltexts/divineliturgy.
18. Hopko, The Orthodox Faith, vol. 2, "Epiklesis," https://www.oca.org/orthodoxy/the-orthodox-faith/worship/the-divine-liturgy/epiklesis.
19. Adrian Fortescue, "Epiklesis," The Catholic Encyclopedia, vol. 5 (1909), https://www.newadvent.org/cathen/05502a.htm; Fortescue, "Liturgy of the Mass," The Catholic Encyclopedia, vol. 9 (1910), https://www.newadvent.org/cathen/09790b.htm.
20. Fortescue, "Epiklesis" (see note 19), on the Florence debate and Mark of Ephesus's treatise; Council of Florence, Bull of union with the Armenians (22 November 1439), trans. in Norman P. Tanner, ed., Decrees of the Ecumenical Councils, at https://www.papalencyclicals.net/councils/ecum17.htm.
21. Catechism of the Catholic Church 1353, https://www.vatican.va/archive/ENG0015/__P40.HTM.
22. John Goggin, "Liturgical Use of Bread," The Catholic Encyclopedia, vol. 2 (1907), https://www.newadvent.org/cathen/02749a.htm.
23. Adrian Fortescue, "Michael Cærularius," The Catholic Encyclopedia, vol. 10 (1911), https://www.newadvent.org/cathen/10273a.htm.
24. Council of Florence, Laetentur caeli (6 July 1439), in Tanner (see note 20).
25. Catechism of the Catholic Church 246-247, https://www.vatican.va/archive/ENG0015/__P17.HTM.
26. A. Maas, "Filioque," The Catholic Encyclopedia, vol. 6 (1909), https://www.newadvent.org/cathen/06073a.htm.
27. Adrian Fortescue, "Canon of the Mass," The Catholic Encyclopedia, vol. 3 (1908), https://www.newadvent.org/cathen/03255c.htm.
28. "The Divine Liturgy according to the Rite of Saint Gregory," St Gregory the Great Orthodox Church (Antiochian Archdiocese, Western Rite Vicariate), https://www.stgregoryoc.org/article/the-divine-liturgy-according-to-the-rite-of-saint-gregory/. On the rite's origin in the Roman Mass, see "Antiochian Western Rite Vicariate," Wikipedia, https://en.wikipedia.org/wiki/Antiochian_Western_Rite_Vicariate.
29. The letter to Dom Gérard Lafond appeared in La Documentation catholique 67 (1970): 215-216, 343; summarized with the Madiran claim in "Ottaviani Intervention," Wikipedia, https://en.wikipedia.org/wiki/Ottaviani_Intervention, citing Michael Davies, "The Ottaviani Intervention, Part I," The Angelus (May 1983).

Bibliography

Primary sources

• The Holy Bible, New King James Version. Nashville: Thomas Nelson, 1982.
• Pius V. Quo Primum. 1570.
• Council of Florence. Laetentur caeli and the Bull of union with the Armenians. 1439. In Decrees of the Ecumenical Councils, ed. Norman P. Tanner. London and Washington, DC: Sheed and Ward and Georgetown University Press, 1990.
• "The Divine Liturgy of St. John Chrysostom." American Carpatho-Russian Orthodox Diocese of North America.
• "The Divine Liturgy according to the Rite of Saint Gregory." St Gregory the Great Orthodox Church, Antiochian Western Rite Vicariate.

Orthodox sources

• Hopko, Thomas. The Orthodox Faith, vol. 2, Worship. Orthodox Church in America.
• Hilarion (Alfeyev), Metropolitan. Interview with Kommersant on the Old Believers. Department for External Church Relations, Moscow Patriarchate, 2021.

Other scholarship and reference

• Taft, Robert. "The Liturgy of the Great Church: An Initial Synthesis of Structure and Interpretation on the Eve of Iconoclasm." Dumbarton Oaks Papers 34/35 (1980-81): 45-75.
• The Catholic Encyclopedia. New York: Robert Appleton, 1907-1912. Articles "Canon of the Mass," "Epiklesis," "Liturgy of the Mass" and "Michael Cærularius" (Adrian Fortescue); "Filioque" (A. Maas); "Liturgical Use of Bread" (John Goggin).
• Clay, J. "Old Believers." Encyclopedia of World Cultures.

Sources from the tradition being discussed (Roman Catholic)

• Second Vatican Council. Sacrosanctum Concilium. 1963.
• Paul VI. Missale Romanum. 1969.
• General Instruction of the Roman Missal. 2002.
• Ottaviani, Alfredo, and Antonio Bacci. Letter to Paul VI with the accompanying critical study of the Novus Ordo Missae. 1969.
• John Paul II. Ecclesia Dei. 1988.
• Benedict XVI. Summorum Pontificum and Letter to the Bishops. 2007. Letter to the Bishops on the remission of the excommunications. 2009.
• Francis. Traditionis Custodes and Letter to the Bishops. 2021.
• Catechism of the Catholic Church, 2nd ed. Vatican City: Libreria Editrice Vaticana, 1997.