Nick Kamas – Medieval Studies Research Blog: Meet us at the Crossroads of Everything

October 1, 2025October 2, 2025

(Pseudo-) Peter Damiani and the Reception of the Schism

In stark contrast to the almost non-reception of the events of 1054 in the literary Byzantine world, discussed here, on the Latin side of the equation, the report of the legation penned by Cardinal Humbert of Silva Candida quickly found its way into various historical chronicles and into theological literature. Two particularly fascinating examples that appear in Patrologia Latina 145 are both published under the name of Peter Damiani, who was, together with Humbert himself, one of the leading members of the papal curia in the mid-eleventh century. Although he would not be elevated to the cardinalate until 1057, under Pope Stephen IX, by the time of Humbert’s legation to Constantinople he was already active in attending various synods and had written the deeply influential Liber Gomorrhianus (addressed to Pope Leo IX). What makes these two works interesting, in light of their purported joint authorship, is that they take views of the azyme conflict (the use of unleavened bread in the celebration of the Eucharist) that are at odds both with each other and with the stance adopted by the Humbertine legation.

Photograph of a bust of Peter Damiani taken from the Florentine church of Santa Maria degli Angeli. Credit to Srnec at English Wikipedia. CC 2.5.

The first example is a letter fragment written by Peter Damiani to Henry, the Archbishop of Ravenna, most likely between 1052 and 1058 [1]. The text is eye-opening both for the historian and for the contemporary canonists, so I’ll cite the full text of Fr. Blum’s translation:

…Just as it makes little difference whether at Mass we offer wine or unfermented grape juice, so, it seems to me, it is all the same whether we offer leavened or unleavened bread. For that “living bread that came down from heaven,” just as he wished to manifest himself under the appearance of wheat, he did so also under the form of the vine. “Unless,” he said, “a grain of wheat falls into the ground and dies, it remains a solitary grain.” And again, “I am the real vine.” Therefore, it suffices for me to offer either whatever is made from grain or whatever is produced by the vine. Nor am I too careful to inquire whether the bread was preserved in an immature dough until it could ferment, or also whether the grape juice was kept in a vat until it could turn into what one calls wine. But since it is not my purpose here to discuss these matters, I leave them to be handled by others…. [2]

Peter Damiani here showed himself to be vastly more permissive than most of the mainstream Latin West when it comes to the correct materials for confecting the Eucharist, and even more tolerant than the legates to Constantinople. Humbert, while he tacitly acknowledged that the Greek practice of using leavened bread was permissible, also had a clear preference for the unleavened Latin host. Peter, interestingly, does not here even mention the Greek practice: his letter is entirely within the context of the Latin rite, addressed to an archbishop of an (admittedly Byzantine-influenced) Latin see. This text allows us to see an approach very different from the one that appears in the aforementioned Liber Gomorrhianus. Given the fact that this was a topic of considerable polemics when he wrote the letter, Peter Damiani appears as a moderating, or even progressive, voice in the conflict.

What a surprise, then, when we examine the second text, taken from the Expositio canonis missae. The work as a whole falls into the genre of Mass commentaries, theological treatises that explain the various ritual components of the eucharistic celebration with historical or scriptural parallels and allegory. Fairly early in this treatise, while discussing the phrase “He took bread” (“accepit panem”) the author complains:

Leavened bread should not be offered in the sacrifice, both by reason of deed and by reason of the mystery. As is read in Exodus: “Leaven signifies corruption”, and as the Apostle witnesses: “A little leaven corrupts the whole lump”. But the Greeks, persisting in their error, celebrate [the Eucharist] from leaven. [3]

Now present is a direct mention of the conflict with the Greeks, using scriptural references that were first applied to the debate by the Humbertine legation. And gone is the tolerance of the previous passage, in which the matter of the Eucharist – so long as it comes from grapes and wheat – is a matter of indifference. Instead, for the author, the use of leavened bread violates the spiritual message of the scriptures, signifying corruption, and is therefore wholly unsuitable for the celebration of the Eucharist.

The wildly divergent views, of course, lead the reader to question the traditional attributions of authorship for one or both of the passages, and indeed, the Expositio canonis missae has caught the attention of several scholars for containing passages that seem out of place in the literary corpus of Peter Damiani. In particular, the text uses the word “transubstantiation” (“transubstantiatio”), which would be the first appearance of this terminology if it could, in fact, be dated to the middle of the eleventh century. It is this terminological incongruity that caused Joseph de Ghellinck to conduct a line-by-line comparison with other commentaries on the Mass and to conclude that the Expositio postdates not only the De sacramentis of Hugh of St. Victor (d. 1141) but also the De sacro altaris mysterio of Lothar of Segni (later Pope Innocent III), which was written in 1198 [4]. The true date of composition, then, would fall somewhere around the turn of the thirteenth century, about a hundred and fifty years after originally supposed.

When applied specifically to the passage about leavened bread, this reattribution to an anonymous author of the thirteenth century clears up a couple of difficulties. In the first place, the notion of the Greeks persisting “in their error” makes much more sense with the later dating. The use of un/leavened bread in the Eucharist didn’t arise as a point of contention until the 1050s, so the Greeks couldn’t have persisted in the error for very long if it had been Peter Damiani admonishing them. By the year 1200, of course, Latin polemicists could much more reasonably suppose that the Greeks had been given sufficient warning, and therefore that their continued use of leavened bread qualified them as “persisting” (“pertinaces”). Similarly, the hard-and-fast rule that “leavened bread should not be offered” is much more typical of the later period, in contrast with the more permissive attitude found in the eleventh century. We see, for example, an identical notion, in nearly identical phrasing expressed in Lothar’s De sacro altaris mysterio: “Not leavened bread, but rather unleavened, should be offered in the sacrifice, both by reason of deed and by reason of the mystery” [5].

But I want to conclude with an emphasis on the relative openness and permissiveness of the mid-eleventh century. Contrary to the reputation that the events of 1054 have developed in the centuries since, the Latin Christians at that time had only begun to develop their stance on the various points under discussion, un/leavened bread being maybe the most important among them. Had the more irenic figures like Peter Damiani (and even Humbert!) exercised a little more influence on this topic, the West might have maintained a more permissive tone by the time of the authorship of our Pseudo-Peter, and indeed, perhaps a different approach taken under the leadership of Innocent III, who had clearly been swayed by a century and a half of increasing aggressive liturgical polemics in his approach to the Greek rite. Whether openness to a variety of liturgical forms could have prevented the entirety of the calamity of the Fourth Crusade is doubtful, but it certainly couldn’t have hurt.

Nick Kamas
PhD in Medieval Studies
University of Notre Dame

For the Latin text and date, see Kurt Reindel (ed.), Die Briefe des Petrus Damiani, MGG Briefe d. dt. Kaiserzeit 4.2, (München, 1988): 1–2.
Owen Blum (trans.), Peter Damian, Letters 31–60, The Fathers of the Church: Medieval Continuation, (CUA Press, Washington, D.C., 1990): 215.
(Ps.) Peter Damiani, Expositio canonis missae, PL 145.88. “Panis fermentatus non debet offerri in sacrificium, tum ratione facti, tum ratione mysterii. Sic legitur in Exodo. Fermentatum etiam corruptionem significat, teste Apostolo: modicum fermentum totam massam corrumpit. Graeci tamen in suo pertinaces errore de fermento conficiunt.”
Joseph de Ghellinck, Le mouvement théologique du XII^e siècle: études, recherches et documents (Paris: Librairie Victor LeCoffre, 1914), 355–359.
Lothar of Segni (Pope Innocent III), De sacro altaris mysterio, PL 217.854. “Panis autem non fermentatus, sed azymus debet offerri in sacrificium, tum ratione facti, tum etiam ratione mysterii.”

July 9, 2025August 5, 2025

Greco-Latin Polemic and the Problem of the Single Immersion Baptism

Of the many issues that rose to the fore in the course of the conflicts between the Latin and Greek churches during the Middle Ages, one of the most consistent, and to me, surprising, was the repeated accusation that the Greeks rebaptized Latin Christians when they, for whatever reason, wished to switch their ritual use (what we would now understand as a “conversion” between different denominations). Although the veracity of these claims has been debated, I think, as I have written elsewhere, that there is good reason to believe that the Greeks really did rebaptize Latins. Complaints about the practice began in the mid-11th century with Cardinal Humbert of Silva Candida, who was elsewhere highly accurate in his claims about liturgical practice, and continue well into the 13th century, including an honorable mention in the canons of the Fourth Lateran Council under Pope Innocent III.

What is less clear, though, is why the Greeks were so keen to rebaptize their Latin cousins. It is tempting to see rebaptism as symptomatic of more ethereal theological topics, in which the perceived differences between the two churches was sufficiently great that the Greek clergy (or at least a subset of them) felt the need to mark the reception of these “converts” from heresy by means of the administration of the sacrament. Certainly this understanding had precedent: as early as 325, the canons of the First Council of Nicaea mandated the reception of Paulianists, who were nontrinitarians, by means of baptism. But I think that this understanding is a mistake with reference to the Latin/Greek conflict. Especially in its earlier phase, in the 11th century, there was no general sense of lasting division: the Greeks generally viewed the Latins as wayward brethren to be corrected, not as heretics utterly outside of the Church, and therefore rebaptism can’t be understood as a requirement resulting from serious deficiencies in the faith on the scale of nontrinitarianism.

Rather, I think that these rebaptisms were because of perceived ritual deficiencies in the Latin rite of baptism, and particularly, in the idea that the Latins were prone to using a single immersion when administering the sacrament. And when looking at this possibility we find a much greater incidence of Latin complaint and Greek explanation. Shortly after Cardinal Humbert complained about rebaptisms, Michael Cerularius, the Patriarch of Constantinople, wrote to Peter, the Patriarch of Antioch, that the Latins performed baptism with a single immersion [1]. The two centuries that followed saw repetitions of both: Odo of Deuil, Leo Tuscus, an anonymous Dominican author writing from Constantinople in the mid-13th century, and Jerome of Ascoli (i.e., Pope Nicholas IV) all noted that Latin Christians were being rebaptized. The “Byzantine Lists”, a genre of polemic that enumerated liturgical and cultural “errors” committed by the Latins, again and again returned to the notion that the baptism of the Latin rite was performed through a single immersion [2]. In doing so, the authors of these lists were implicitly invoking another of the canons of the early church, this time from the so-called Apostolic Canons (no. 50): “If any Bishop or Priest does not perform three immersions in making one baptism, but only a single immersion […], let him be deposed” [3]

Assuming that my conclusion is correct, that Greeks rebaptized Latins with some degree of frequency because they believed their form of the sacrament to be ritually defective, the question that next arises is how the Greeks came to hold that belief. Prior to the widespread adoption of affusion or aspersion in the Latin West, the form of baptism appears to have been similar to that of the Greek East: a full triune immersion, done together with the invocation of the persons of the Trinity. We see this clearly referenced as late as the early 13th century, when Pope Innocent III, writing to the Maronite Church, instructs them to invoke the Trinity only once “while completing a triple immersion” [4]. The great exception to the standard Latin practice was the famous license given by Pope Gregory the Great to the church in Spain to baptize with a single immersion as a way to signify the oneness of the Trinity and thereby to combat Arianism. This practice was further codified by the 633 Council of Toledo and its existence confirmed in the works of Isidore of Seville and Ildefonsus of Toledo [5]. The practice is referenced twice more, toward the end of the eighth century, in the letters of Alcuin of York, who acknowledged that the practice existed in certain parts of Spain only long enough to condemn the people who baptize in this way as “neglecting to imitate, in baptism, the three-day burial of our Savior” [6]. They maintain this custom, according to Alcuin, “contrary to the universal custom of the holy Church” making Spain the “wet-nurse of schismatics” [7].

Returning, then, to the polemics of the Greeks, is it possible that their complaints about a Latin single-immersion baptism stemmed from the Spanish practice? I see no other possible cause, although this feels unsatisfactory as an explanation. At most, the single-immersion baptism was a regionalism confined to the Iberia, and the opposition of Alcuin, the great champion of Romanization in the West, makes it unlikely that it would ever have spread further than its native peninsula. Indeed, the gradual imposition of the Roman rite throughout the Christian West likely reduced the frequency of single-immersion baptisms within Spain itself in the centuries following the initial permission of Pope Gregory. If the practice survived at all by the mid-11th century, when Cardinal Humbert and Patriarch Michael wrote their respective complaints – and I haven’t found any evidence from that time for or against – it would probably have been a very rare indeed for someone baptized “incorrectly” to have been found in Constantinople.

Pending further evidence, then, we are left with the Greeks reacting at most to an improbability, and more likely to outdated information. While I fully acknowledge that it’s no more than supposition on my part, my best guess is that the works either of Gregory the Great or of Isidore of Seville (or of both, or of someone else entirely) were received in the theological circles of 11th-century Constantinople, leaving the mistaken impression that the practice of single immersion baptism was common in the West. From there, the notion that the Latins performed this sacrament incorrectly, along with most of the others, proved hard to dislodge.

Nick Kamas
PhD in Medieval Studies
University of Notre Dame

Cornelius Will, ed., Acta et Scripta quae de controversiis ecclesiae graecae et latinae saeculo undecimo composita extant (Leipzig: N. G. Elwert, 1861), 153 (Humbert) and 182 (Michael).
Tia M. Kolbaba, The Byzantine Lists: Errors of the Latins (Urbana and Chicago, University of Illinois Press, 2000), 192.
The Rudder, trans. Ralph Masterjohn (West Brookfield, Massachusetts: The Orthodox Christian Educational Society, 2005), 179.
“in trina immersione unica tantum fiat invocatio Trinitatis”. No. 216. Acta Innocentii III, ed. P. Theodosius Haluščynskyj (Vatican, Typis Polyglottis, 1944), 458.
J.D.C. Fisher, Christian Initiation, Baptism in the Medieval West (London: S.P.C.K., 1965), 91.
“triduanamque nostri salvatoris sepulturam in baptismo imitari neglegentes”. Ep. 139. Ed. Ernest Duemmler, MGH Epp. 4 (Berlin: Weidmannos, 1895), 221.
“[…] Hispania – quae olim tyrannorum nutrix fuit, nun vero scismaticorum – contra universalem sanctae ecclesiae consuetudinem […].” “Adfirmant enim quidam sub invocatione sanctae Trinitatis unam esse mersionem agendam.” Ep. 137. Ibid., 212.

March 12, 2025March 12, 2025

Eastern Liturgical Rite(s) under Pope Innocent III

The Roman Pontiffs, over the course of the second half of the Middle Ages, were not noteworthy for their enthusiasm for the liturgical rites of the Eastern Christian Churches. In few cases was this made clearer than in the aftermath of the Fourth Crusade, an especially distasteful moment of intra-Christian violence that left the Latin crusaders, originally destined for the Holy Land, instead governing the capital city of the Eastern Roman Empire. Although he initially decried the violence, Innocent III, then the Pope of Rome, quickly attempted to eradicate some of the liturgical differences that had plagued relations between the Roman and Constantinopolitan Churches for the previous century and a half, ever since the ill-fated trip of Cardinal Humbert and his co-legates to Constantinople in 1054. Among other changes, all new bishops, whether Greek or Latin, were to be consecrated according to the Roman rite, Latin clergy were to be appointed to those churches that had been abandoned by Greek priests fleeing the crusaders, and those Greek clergy who remained were to be encouraged to switch to the Latin rite for the celebration of the Eucharist [1]. Although he was not privy to the election of Thomas Morosini as the (Latin) Patriarch of Constantinople in the wake of the city’s conquest, he quickly confirmed him in his office and clarified that he would have the traditional jurisdictional authority of the Constantinopolitan See [2]. All of this transpired prior to the Fourth Lateran Council in 1215, with its famous canon dealing with “the pride of the Greeks against the Latins.”

Pope Innocent III, from the Monastery of Sacro Speco of Saint Benedict – Subiaco (Rome).

Creative Commons CC0 1.0 Universal Public Domain Dedication.

This policy, in fact, marked a sharp deviation from Innocent’s prior treatment of the Greek rite. Too easily forgotten is the fact that the Greeks had a substantial presence in much of the Italian peninsula (and to this day there exists in Italy a few thousand people who speak Griko, essentially a dialect of medieval Greek). Alongside this substantial Greek population were Greek-rite monastic establishments and a number of dioceses served by Greek prelates, all of which were under the ultimate jurisdiction of the See of Rome. Innocent III, in his dealings with these communities prior to the Fourth Crusade, was noticeably less aggressive, balancing his apparent preference for the Latinization of ordination rites with a policy of non-interference on the matter of clerical marriage and active support for Basilian monasteries under his jurisdiction [3].

It has been popular with some modern commentators, Joseph Gill being perhaps the foremost example, while admitting that Innocent III had a distinct preference for the Latin rite, to argue that he was primarily concerned with enforcing (Latin) canon law. In this reading, the chief concern of the papacy was the allegiance of the Eastern clerics; once that had been secured, the secondary priority was to extirpate practices that were actively contrary to the law of the Roman church while at the same time tolerating, to a greater or lesser degree, ritual aspects that didn’t interfere with canonical norms [4].

To see whether this was in fact the case, helpfully, there are two other points of comparison. The activity of the crusaders in the Levant occasioned a resumption of active communication and communion between the Papacy and the Maronite Church. As part of this exchange, Innocent III issued a papal bull in January of 1215 in which he formally accepted the Maronite Church and confirmed several of its privileges. At the same time, though, he demanded certain changes: the Maronite Church must maintain the truth of the filioque, that only a single invocation of the Trinity be made during the rite of baptism, that the sacrament of Chrismation/Confirmation be done only by a bishop, and that the bishops wear vestments according to the Roman use [5]. In Bulgaria, facing a tsar and a primate eager to secure legitimacy for their positions and the autocephaly of the Bulgarian church, the subordination to Rome likewise came with a demand. As in Constantinople following the Latin conquest and in some of the Greek communities in the south of the Italian peninsula, the Roman rite was to be used for the ordination of priests and bishops [6].

These distinct differences in approach gives rise to the obvious questions: Did Pope Innocent III have a consistent stance toward the liturgical rites of the Christian East and, if so, what was it? Is it really fair to suggest that the pope was motivated first, by the question of allegiance, and second, to matters of ritual? Perhaps this was the case, but my sense is that the matters were more closely linked than many commentators assume. My suspicion is that, for Innocent, the willing submission of various Greeks, Bulgarians, and Lebanese to aspects of the Roman rite was itself the proof that they also accepted papal authority more broadly. I think that modern scholarship often fails to appreciate the intimate connection between practice and belief — lex orandi, lex credendi, after all — and that this is especially the case when it comes to the ritual differences that divided the churches of Rome and Constantinople. By requiring concrete changes in ritual practice, down to the style of vestments to be worn by the Maronite clergy, Innocent III caused these churches to give physical, tangible proof that they accepted the teaching, jurisdictional, and legal authority of the Apostolic See.

Nick Kamas
PhD in Medieval Studies
University of Notre Dame

Summarized by Alfred Andrea, “Innocent III and the Byzantine Rite, 1198–1216,” in Urbs capta: La IVe croisade et ses conséquences, ed. Angeliki Laiou (Paris: Lethielleux, 2005), 118–120.
Jean Richard, “The Establishment of the Latin Church in the Empire of Constantinople (1204–27,” in Latins and Greeks in the Eastern Mediterranean after 1204 (London: Routledge, 1989), 49.
Andrea, “Innocent III,” 116–118.
Joseph Gill, “Innocent III and the Greeks: Aggressor or Apostle?,” in Relations between East and West in the Middle Ages, ed. Derek Baker (Edinburgh: Edinburgh University Press, 1973), 103–105.
No. 216, Acta Innocentii III, ed. P. Theodosius Haluščynskyj (Rome: Typis Polyglottis Vaticanis, 1944), 459–460.
Andrea, “Innocent III,” 117. See also Francesco Dall’Aglio, “Innocent III and South-Eastern Europe: Orthodox, Heterodox, or Heretics?” Studia Ceranea 9 (2019), 20.