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Medieval Sourcebook
Patriarch Peter of Antioch: Letter to Patriarch Michael Kerularios (concerning the Schisms of 1054)   
Sometime in June or July 1054.

Peter, Patriarch of the God's City [Antioch] and all the East, to Michael, Patriarch of Constantinople.  Sometime in July or August 1054.  The Greek text is in J.P. Migne, ed., Patrologia graeca, vol. 120, columns 795-816.

In the footnotes, I have attempted to provide both a recent secondary reference which could be used to find additional bibliography for the scholars and research-paper-writing students; and an open-source reference such as Wikipedia for those who are only a little curious.  Please keep in mind that open-source references must be read critically.  For example, while many articles on Wikipedia are irreproachable, some are out-of-date, tendentious, or inaccurate. [Tia M. Kolbaba,]

2.  The sacred letters of Your Holiness say that a rumor has reached your ears that I commemorate the pope in the sacred diptychs and that the other most holy patriarchs do the same thing.1  And [you write] that we must not be so very ignorant, especially me, above all others, since I know, to use your words, that the commemoration of the pope has been cut out of the sacred diptychs from the holy sixth ecumenical council to the present.2 For the pope of that time, Vigilius, did not present himself at the council nor did he anathematize the writings of Theodoret against the correct faith and against the Twelve Chapters of St. Cyril.  And since then, down to the present, the pope has been cut off from our most holy church.3

120: 797/798 A-B:
3.  I was ashamed of these claims contained in the letter of Your Honor,4 nor do I know, believe me, how to express my shame, especially if you have also written to the other most blessed patriarchs in a way similar to what you wrote beforehand to us.  For you have, before examination and comprehension and from empty rumor, depicted something that never happened as if it had happened.  For how could I commemorate the pope while the holy church, according to you, does not commemorate him?  I who am [the church's] pupil and zealot, if anyone is, I who by word and by deed always commend and augment [the church's] privileges?  As for that which you wrote regarding Vigilius, it is not true.  Does this not suggest some sort of negligence on the part of your pious chartophylax?5  For even if the man is as skilled as a sophist in the art of rhetoric, nevertheless he is young and does not have sufficient experience of ecclesiastical affairs.  "He does not have faith," said Ioannes Klimakos, "who is wine just now bottled out of the vat."

4.  Therefore, he who has been charged with such a great rank must judge the texts [that record church history] not casually, but with great care.  For the substance of our hierarchy is the God-given oracle, or the true knowledge of the divine writings--so declared the great Dionysios.  For Vigilius was at the fifth council, when the teachings of the following were dealt with:  Origen, Evagrius, Didymus, and others, including Peter, Severus, and Zoöra, and also Theodoret.  But Vigilius was not at the sixth council.  The interval between these two synods was 139 years.  It did happen, for a brief while, that commemoration was cut off on account of Vigilius's contending with the most holy patriarch Menas [patriarch of Constantinople 536-552] and subjecting him to demotion.  [That schism lasted] until the archbishops made peace and were reconciled with one another.  At the sixth holy synod, on the other hand, the pope was the priest Agatho [678-681], a worthy and divine man who was wise in divine matters.  Read the acts of the sixth council, as it is customary to do on the Sunday after the Exaltation of the Venerable Cross,6 for you will find there that the aforementioned Agatho was gloriously acclaimed in that holy council.

5.  In addition to these things, I myself am also a witness admissible without challenge, and with me many other notable men of the church, that up to the time of the Lord Patriarch of Antioch John of blessed memory, the pope of Rome, also named John,7 was commemorated in the sacred diptychs.  And when I went to Constantinople 45 years ago, under the Lord Patriarch Sergios [Sergios II, 1001-1019] of blessed memory, I found that the pope at that time was being commemorated in the divine service along with the other patriarchs.  How the commemoration of the pope was later cut off and for what reason, I do not know.  But since I know these things, I do not want you to do anything further regarding the commemoration of the pope.

6.  Now, we have surveyed the Roman errors which you enumerated.  Some of them seem abominable and should be fled; others are curable; still others can be overlooked.  For what does it matter to us if their bishops shave their beards8 and wear rings as a symbol (as you have written) of their betrothal to the holy church of God?9  For we also make a garara10 on our heads wholly in honor of the Prince of the Apostles, Peter, on whom the great church of God was founded.  For that which some impious men have made into an insult to the saint, we who are pious have made in his honor and for his glory:  Romans, on the one hand, shaving their beards and we, on the other, practicing the tonsure on our heads.  We ourselves also wear gold--putting on gold-spangled eucheiria, epimanika, and epitrachelia.11

7.  And as for their eating unclean things12 and their monks eating pork fat,13 you will find, if you will investigate, that these things are done also among some of our own people.  For Bythinians, Thracians, and Lydians eat magpies, jackdaws, turtle-doves, and porcupines [and] the Fathers left the use of these things as a matter of indifference.  For no creature of God is to be rejected if it is received with thanksgiving.14 And that sheet of fine linen let down from heaven persuades me, the sheet in which were all the four-legged beasts of the earth, the wild animals, the creeping things, and the birds of heaven, and Peter heard from God, "Rise, Peter, kill and eat."  And he replied, "Surely not, Lord, for nothing at all common or unclean has ever passed my lips."  And again he heard, "What God has cleaned, do not make common."15 

8.  This is the place, too, for the saying of St. Basil:  "Even as we distinguish the harmful from its opposite among vegetables, so we also divide the harmful from the useful among meats, since hemlock is a vegetable, just as a vulture is meat, but just as no one in his right mind would eat henbane, so no one would touch dog’s meat unless he was constrained by such a great necessity that he became lawless."16  And the addition of pig's fat to the pulse and the vegetables was conceded and allowed by the holy Fathers--especially among those who cannot obtain usable oil.


11.  But an evil, even the evilest of evils, is their addition to the creed, thus:  "And in the Holy Spirit, the Lord, the Giver of Life, who proceeds from the Father and the Son."17  For if the gospel is the same among us as among the Romans, whence have they, learning something more, made such a monstrous addition?  For when the holy gospel according to John teaches quite precisely about the Holy Spirit, it distinctly states the following:  “If you love me, keep my commandments.  And I will ask the Father to give another Comforter to you, to remain with you to the end, the Spirit of truth, whom the world cannot understand because the world neither sees the Spirit nor knows him.  But you know him, for he remains among you and is in you."18  And then a little later:  "The Comforter, the Holy Spirit, whom the Father will send in my name--he will teach you everything and he will remind you of everything which I have told you."19  And again:  "When the Comforter comes, whom I will send from the Father, the Spirit of Truth, who proceeds from the Father, he will bear witness concerning me."20  And still more:  "I still have many things to tell you, but you cannot yet bear them.  But when that one comes, the Spirit of Truth, he will lead you into the whole truth, for he will not speak from his own [authority] but he will speak whatever he hears, and he will declare to you the things which are to come.  He will glorify me, for he will take what is mine and declare it to you.  Everything which the Father has is mine.  Therefore I say that he will take what is mine and declare it to you."21

12.  And if the evangelist has so exceedingly clearly declared this, what orthodox person will dare or will be able to add to or to subtract from it?  For when it concerns something which the divine Scripture clearly declares, it is not necessary to take a vote, but only to follow.  But it seems that the Romans have lost their exemplar of the First Council of Nicea because the race of the Vandals ruled Rome for a long time. 22  From the Vandals they also learned to Arianize23 and to perform baptism in only one immersion, if this is true, as you said.24  For the wise and saving symbol [creed] of the divine race suffices for us in perfect knowledge and confirmation of piety.  It teaches the perfect story about the Father, the Son, and the Holy Spirit, and it reveals the incarnation of the Lord to all who receive it with faith.  But those who add anything to it or subtract anything from it we anathematize.  The Apostle says, "If anyone should evangelize you with something apart from what you received, let him be anathema."25

13.  Nor do we accept the other addition which they have made, namely:  "One holy, on Lord, Jesus Christ, in the glory of God the Father, through the Holy Spirit", although it is possible that if we understood it piously it would do no harm to right faith.  For it seems that this is equivalent to that point in our service when the holy bread is elevated and the people exclaim, 'One Holy, one Lord, Jesus Christ, in the glory of God the Father.' Then the archdeacon and the one who is raising up the second chalice take up the first and the second chalice and say, 'Fill, Lord.'  And when they throw a piece of the consecrated elements into [the chalice], we exclaim, 'the fullness of the Holy Spirit.'26

14.  For it is good that we, looking always to good will, should consent always to peace and brotherly love, especially so long as neither God nor the faith is in danger.  For they are our brothers, even if it happens that, through rusticity and lack of education, they have frequently fallen from what is seemly, following their own will.  We do not demand the same accuracy in barbarous peoples as we demand among those who have been brought up in doctrine.  For it is a great thing if only the life-giving Trinity is preached correctly among them, and the mystery of the economy27 of the incarnation is in agreement with our doctrine.  Indeed we will certainly not praise or accept, if it is true, that they do not permit priests who have lawful wives to touch the sacraments;28 nor, as you have written, that they behave in the same way in the first week of the holy fasts as [in the week of] meat and cheese.29

807/808 A-B
15.  For the question of azymes [using unleavened bread in the Eucharist] has already been sufficiently scrutinized by us, and has been overturned and discarded on the grounds that it does not conform to ecclesiastical tradition (as Your Holiness knows, since you happened upon a copy of the letter we sent to the Bishop of Venice).30  Unless, consulting the canonical saying--"It seems good to all to use the ancient customs"--they say that the custom of azymes is ancient among them.  As for their eating strangled things,31 and two brothers uniting in the flesh with two sisters,32 I think that these transgressions are not done with the injunction and consent of the pope or of the other bishops.  Rather, they are done by the audacity of those who choose to do these things.  And many of this sort of lawless and forbidden deeds are being committed in our Roman33 dominion without us knowing.

16.  For regarding abstaining for strangled meat, the book of the Acts of the Apostles speaks clearly, where James, the brother of the Lord, appears, saying, "From the beginning all his deeds are known to God.  So I judge that we ought not to trouble unduly those among the gentiles who have turned to God, but to write to them to abstain from meat offered to idols, from unchastity, from what is strangled, and from blood."34  And I have never been persuaded that the pope and the other bishops lack awareness of such a book, since they have accurate knowledge of the arrangement of the other Scriptures, and so why would they neglect and accept such a transgression?  But you will find, both within the city and without, many who eat pigs' blood.  And further evidence of this are the sausages filled with pigs' blood set forth among the offerings of taverners.

17.  But see, most honorable lord, how, while we overlook or even allow many things which our people do wrongly, we babble about the more suitable thing and meddle in the affairs of others.  Shall I say more?  Now don't get upset.  In the most righteous monastery of Studios, deacons are girded, doing something which does not follow ecclesiastical tradition.  And consider, how, after much labor and in spite of much zeal, you have not been able to excise such a peculiar custom.35  And if we cannot prevail against those under us, how can we turn that proud and haughty race away from their own customs?  For it is enough, as I said, if the divine is preached correctly among them, and if he is praised and glorified in accordance with the word of truth and in common with us.

18.  For Your Holiness does well and acts in a way pleasing to God when you resist the addition to the holy creed and their refusal to communicate with the gifts sanctified by a married priest.  And do not ever stop resisting this and persuading them from the holy Scriptures and from the recorded evangelical preaching, until you have them in agreement with the truth and praising the same doctrine as us regarding the divine procession of the Holy Spirit from the Father.  But I think the other things (especially since most of them are false) should be overlooked, since the word of truth is not at all harmed by them. For we should not readily be persuaded by vain accusations, nor believe in our own suspicions, and we should not change the things which are established and right.

19.  Thus it is exceedingly necessary, Most Holy Lord, that when a new pope has been elected, Your Reverend Perfection should explain all these things to him through honorable letters; and thus the Lord will help you in all matters and provide his grace in this to your holiness.  For perhaps, as the Apostle says, if we gently gather together those who think differently, God will give repentance for the knowledge of truth, and they will stop their great, strife-loving contention, and become prisoners of his will.  But perhaps the pope will also defend his church, saying that the things rumored about the Romans are not true or that if these things are done by some individuals, it is not in accordance with his opinion and wisdom.

20.  But who could consider this accusation admissible--that Romans neither revere the holy and reverend images nor honor the relics of the saints, when the relics of the saints and princes Peter and Paul lie among them, in which they seem to vaunt themselves and glory magnificently--more than all the other Roman narratives and successes of which every history and every poem is full?  Since the pope of Rome, Hadrian, was present at the Seventh Council with the other most holy patriarchs, and anathematized the alien novelty of the heretic iconoclasts who accused the Christians, how would anyone allow that the holy and reverend icons are not honored among the Romans?36  And especially since many holy icons have been transported from Rome to Constantinople, being eminent and accurate images of the ones who are their prototypes.  Sometimes even here we see Franks37 who come to town and enter our holy temples and render all honor and reverence to the holy icons.

21.  And I exhort, entreat, ask, and mentally embrace your holy feet, that Your Divine Blessedness might lack too great a strictness and concur in those matters.  For it is to be feared that while you wish to mend that which is torn, you will make the tear worse, and, while you are zealous to set right that which has fallen, you will cause a worse fall.  But consider if it is not clearly for this reason--that is, for this long separation and dissension which has divided this great apostolic see from our holy church--that all evil has multiplied in life and the whole cosmos fares ill; and so the kingdoms of all the earth are in turmoil, and everywhere dirges and cries of woe and famines and plagues are unremitting in countryside and town; and nowhere in any way do our armies prosper.

22.  As for me, I will make my opinion clear: if ever they would correct the addition to the holy creed, I would demand nothing else, leaving as a matter of indifference, along with all the other matters, even their fault regarding the unleavened bread.  And this although I have clearly demonstrated in what I sent to the bishop of Venice that the meal in which our Lord and Savior Jesus Christ offered the mystery of the holy teaching to his disciples took place before Passover, at which time it was not required to eat unleavened bread.  And this also I exhort Your Divine Blessedness to accept, so that you may not, by demanding everything, lose everything.  These things are sufficient to present our opinion regarding the things which you indicated, and to move your soul to mercy, even if the argument rather rushes on to the elaboration and explanation of many other propositions and rather esoteric questions.



1 The Orthodox Churches of Byzantium kept lists of the leaders of other churches whom they prayed for in regular worship services.  These lists, often referred to as "the diptychs," included only those churches and their leaders who were considered orthodox.  Therefore, to "commemorate a bishop in the diptychs" was to say that you considered him orthodox.  In other words, Keroularios is arguing here that the bishop of Rome, the Pope, is not orthodox and should not be commemorated in the prayers of orthodox churches.  See

2 The Sixth Ecumenical Council, also known as the Third Council of Constantinople, was held in Constantinople in 680-681 CE.

3 Actually, Vigilius (537-555) was pope during the Fifth Ecumenical Council, which took place in 553.  The pope at the time of the Sixth Ecumenical Council was Agatho (678-681).  Keroularios is talking here about the events and condemnations at the Fifth Ecumenical Council.  See Richard Price, trans. and comm., The Acts of the Council of Constantinople of 553, with Related Texts on the Three Chapters Controversy (Liverpool:  Liverpool University Press, 2009). . The condemnations referred to are those known as the "Three Chapters"; see Price, Acts of the Councils of … 553; also Celia Chazelle and Catherine Cubitt (eds), The Crisis of the Oikoumene. The Three Chapters and the Failed Quest for Unity in the Sixth-Century Mediterranean (Turnhout 2007).  (There is also a Wikipedia article on the Three Chapters, but as of 2019 it is biased and out-of-date.)

4 In Byzantine letters, the letter writer often uses elaborate honorific names for his addressee, such as "Your Perfection", "Your Incomparable Virtue."  Compare the English use of "Your Majesty," "Your Highness," or "Your Honor."

5 The chartophylax of the patriarchate of Constantinople was essentially the librarian and archivist.  He would often compose letters on the patriarch's behalf, and he was expected to do necessary research for such letters in the archives of the patriarchate.  Peter is here blaming the chartophylax for the errors in Keroularios' letter.  See

6 The Feast of the Elevation (or Exaltation) of the Cross is celebrated on September 14.

7 Because the chronologies of the patriarchs of Antioch are a bit confused and there were nineteen popes named John, we cannot be sure who Peter means here.

8 As a general rule, Greek men wore long beards, and Latin men shaved.  Greek priests were almost invariably bearded, while many Latin priests were clean-shaven.  See Giles Constable, “Introduction. Beards in History,” in Apologiae Duae.  Gozechini Epistola ad Walcherum.  Burchardi, ut videtur, Abbatis Bellevallis Apologia de Barbis, ed. R.B.C. Huygens (Corpus Christianorum, Continuatio Medievalis 62; Turnholti, 1985), pp. 46-130.  Kolbaba, Byzantine Lists, 56-57.  A bit over-the-top and inaccurate in some historical details, this article is nevertheless a fun open-source account of the facial-hair differences of opinion:

9 Eastern bishops did not wear rings, while rings were part of the regalia of Latin bishops. See Kolbaba, Byzantine Lists, 53; Oxford Dictionary of Byzantium vol. 1, 185-186, "Arrha Sponsalia."

10 In the Migne edition, this is identified as a word of Syriac origin meaning clerical tonsure.  That it is something on the head, surely, is clear from context, but I question the identification of this word with tonsure because Peter mentions tonsure by its normal name in the next sentence:  papalethra.  Any suggestions welcome at

11 Keroularios had accused Latins of overly elaborate liturgical garments; Peter here lists Greek liturgical garments that are equally elaborate.

12 Keroularios had accused westerners of eating various unclean foods, but according to the New Testament and most church law, no meat was unclean for Christians, but see Kolbaba, Byzantine Lists, 35-37, 145-162 for Byzantine complaints about what Latin Christians eat.

13 Monks of the eastern churches generally observed an entirely vegetarian diet, while some monks in the Latin West were allowed limited amounts of meat, including lard.  All of this varied greatly from monastery to monastery, so wholesale comparisons are inevitably inaccurate.  See Kolbaba, Byzantine Lists, 46-47.

14 Cf. 1 Tim 4:4.

15 Cf. Acts 10:9-16.

16 Basil of Caesarea, Letter 236:  Yves Courtonne, Saint Basile, Lettres, vol. 2 (Paris: Société d’Édition ‘Les Belles Lettres’, 1961; English trans., Agnes Clare Way. Saint Basil. Letters. Vol. 2 (186-368) (New York: Fathers of the Church, Inc., 1955); older English trans. available online: .

17 For the controversy about the addition to the creed, see A. Edward Siecienski, The Filioque.  History of a Doctrinal Controversy (Oxford: Oxford University Press, 2010).

18 Jn 14:15-17.

19 Jn 14:26.

20 Jn 15:26.

21 Jn 16:12-15.

22 In this rather condescending passage, Peter suggests that the Latin Church has introduced an error to the creed because of the influence of the northern European "barbarians" (Goths, Vandals, Franks and others) who conquered Rome in the early Middle Ages.

23 "To Arianize" in this context means to teach that the Son is less than or subordinate to the Father.

24 The Byzantine Orthodox Church insisted that baptism include three full immersions.  By the 11th century, Latin practice was quite different from Greek practice, and sometimes included only one immersion, or even no full immersion.  Kolbaba, Byzantine Lists, 43-44.

25 Cf. Gal 1:9.

26 See Kolbaba, Byzantine Lists, 65.

27 The Greek word oikonomia here means something like the western concept of God's providence:  it is God's arrangement and plan., especially the section on "Divine Economy."

28 In the Byzantine Orthodox Church, a man could be married before he was ordained to the priesthood.  In the western churches, there seems always to have been a strong preference that ordained clergy be unmarried and celibate, although clerical celibacy was not universally observed.  In the eleventh century, at the very time this text was written, the reformers of the Latin Church were leading a push to remove all married priests from the priesthood and enforce celibacy for the clergy.  Kolbaba, Byzantine Lists, 39-40. is useful but a bit biased in the direction of contemporary Roman Catholic teaching.

29 The differences between the length of Lent in the Latin and Greek churches are complicated and have a complicated history.  For a general discussion, see Kolbaba, Byzantine Lists, 41-43.  See and

30 One of the differences between the ritual of the Eastern Orthodox Churches and the Roman Catholic churches is the kind of bread used in the Eucharist (also called the Mass, the Divine Liturgy, and the Lord's Supper).  The Orthodox Churches use leavened bread; the Roman Catholic churches use unleavened bread (wafers). Tia Kolbaba, The Byzantine Lists.  Errors of the Latins (Urbana:  University of Illinois Press, 2000), 37-39.  A pretty balanced and mostly accurate account online:

31 Eating meat that has not been bled properly is forbidden in the New Testament (Acts 15:19-20, 28-29), and by various church laws thereafter.  Kolbaba, Byzantine Lists, 35-37.

32 In the Byzantine Orthodox Church, the marriage of two brothers to two sisters was considered incestuous.  On differences in the marriage laws between the Roman and Constantinopolitan Churches, see Kolbaba, Byzantine Lists, 44-46.

33 The Byzantines called their empire the Empire of the Romans.

34 Acts 15:18-20.

35 Michael Keroularios had a number of conflicts with the monastery of Stoudios, located in Constantinople.  He objected to their revering a former abbot of the monastery as a saint and to a specific use of liturgical vestments within the monastery.  Michael Angold, Church and Society in Byzantium under the Comneni, 1081-1261 (New York:  Cambridge University Press, 1995), 28.

36 Actually, the pope was not present at the Seventh Ecumenical Council, but he did send representatives and he did accept the results of the council.  The Seventh Ecumenical Council was held in Nicea in 787.  Its main focus was the defense of reverence for icons after a period in which such reverence had been condemned as superstition.  The history of this so-called "iconoclast period" in Byzantium has been significantly revised in the last few decades.  For an accessible account, see Leslie Brubaker, Inventing Byzantine Iconoclasm (Bristol:  Bristol Classical Press, 2012).  The Wikipedia article on Byzantine iconoclasm is mostly up-to-date and accurate on this question:

37 "Franks" is here used as a general term for all western, Latin Christians.

Translation and notes © Tia M. Kolbaba, April 2019