Eusebius, Arius, and the Lost "Secret" Ending of the Church History

 The surviving ten books of Eusebius’ Church History end in 324/5 CE, with Constantine’s victory over Licinius and the “peace of the churches.” On the conventional reconstruction, this is the point at which Eusebius decided to stop: a pre-Nicene or just-barely-Nicene history, supplemented later by separate Constantinian works, above all the Life of Constantine (VC) and the Oration in Praise of Constantine. Modern scholarship has tended to take this structure for granted. Eusebius has a ten-book Church History, a four-book Life, and an attached panegyric; any impression of a “missing” extension is explained away as wishful thinking or the result of later readers confusing genres.

This paper argues that the external evidence points in the opposite direction. Taken together, Philostorgius, Photius, and Zonaras preserve the memory of a longer, more explicitly Constantinian and Arian-period Ecclesiastical History—one which extended at least to the accession of Constantine’s sons, treated the Arian controversy and the emperor’s baptism more fully than our text, and was associated in the tradition with Eusebius’ known Arian sympathies. The Constantinian books that survive (VC and the Oration) are not “the rest” of the history; they are what was left, after later redaction and loss, of a larger Eusebian dossier that originally included an Arian-leaning continuation of the Church History itself.

The argument proceeds in four stages. First, I review the testimonia about the scope of Eusebius’ Church History, with special attention to Philostorgius. Second, I examine Photius’ Bibliotheca on Eusebius and argue that the most natural reading of codex 127 is that Photius ascribes to the Ecclesiastical History in many books the very material that is now missing from our text: detailed notice of Arius and a full account of Constantine’s baptism, including the officiant and location. Third, I show that John Zonaras, reading Eusebius through Photius two centuries later, clearly understood Photius this way and, finding no such explicit material in the Eusebian text available to him, accuses Eusebius of concealment and ambiguity. Finally, I place this Photius–Zonaras complex into the broader late antique and medieval tradition that remembers Eusebius as an Arian or ex-Arian, and suggest that suppression or reshaping of a pro-Arian Constantinian continuation is precisely what one would expect in a post-Nicene, anti-Arian textual environment.

1. Philostorgius and the Endpoint of the Church History

The clearest early statement that Eusebius’ Church History extended beyond Constantine’s victory over Licinius is preserved in the Arian historian Philostorgius. In Photius’ epitome of Philostorgius, Hist. eccl. 1.1–2, the Arian author both praises and attacks Eusebius. He commends him “on other grounds as well as on account of his Ecclesiastical History,” but accuses him of serious doctrinal error, particularly in holding that the Deity is unknowable and incomprehensible. Crucially, the epitomator adds: “He too states that Eusebius brought his own history to an end with the succession of the sons of Constantine the Great.”

Taken at face value, this means that Philostorgius knew, or believed that he knew, a version of Eusebius’ Church History whose chronological terminus was not the defeat of Licinius in 324 but the accession of Constantine’s sons in 337–340. That is, he locates the Eusebian endpoint in the Constantinian–post-Constantinian transition, not in the pre-Nicene period.

This notice is often dismissed as confusion, on the assumption that Philostorgius has conflated the Church History with the Life of Constantine or with some other Constantinian dossier. But that move simply assumes what is to be proved. Philostorgius is a careful reader of earlier ecclesiastical historians and is explicitly distinguishing here between “his [Eusebius’] history” and other things. If his statement is even approximately correct, then at least some late antique readers had before them a “Eusebian history” whose narrative extended well into the period of Arian controversy, succession, and division among Constantine’s heirs.

Philostorgius is not alone. Later Latin notices that depend on Greek tradition repeatedly speak of Eusebius’ “many books of ecclesiastical history” and treat his work as a comprehensive record of persecutions, martyrs, and episcopal successions down to his own or very recent times, with special attention to the Constantinian settlement. The exact phrasing varies from Victorius’ Canon Paschalis to the pseudo-Jerome material and Gelasius’ decree, but the cumulative picture is not of a tidy, ten-book pre-Nicene chronicle abruptly terminating before Nicaea, but of a larger historiographic project in which “the ecclesiastical history” and the Constantinian material formed a continuous dossier.

At minimum, Philostorgius creates a problem for any reading of Eusebius that simply assumes our ten-book Church History is all there ever was. If Philostorgius is correct, there was once a longer version of “his history” that extended into the reign of Constantine’s sons. And if he is wrong, we still must explain what Eusebian text or tradition he was misreading—a text that looked, to a fifth-century Arian historian, like a continuous history reaching into the Arian age.

2. Photius on Eusebius: “In These Same Books”

The next key witness is Photius of Constantinople (c. 810–893). In codex 127 of the Bibliotheca, he reviews several of Eusebius’ works. After noting that he has read “four books On the Praises of the Emperor Constantine” and “the Life of Constantine” in four books, which he says recounts the emperor’s deeds “to the end of his life,” Photius continues: “I have also read his Ecclesiastical History in many books, in which he set down the succession of bishops from the time of the apostles, and related the most noteworthy events of the Church, and the conflicts and heresies that arose, down to our own times.”

Then comes the crucial sentence:

“In these same books he often mentions Arius and makes no concealment of his heresy. He also records the baptism of Constantine, stating who baptized him and where. Likewise he does not pass over in silence the things that concern Arius.”

Grammatically, the antecedent of “in these same books” (ἐν τοῖς αὐτοῖς τούτοις λόγοις, or similar) can only be the immediately preceding “Ecclesiastical History in many books.” Photius has already finished with the four-book Life and the four-book Encomium; he now turns to the History and explicitly ascribes to “these same books” three things:

1. frequent mention of Arius, without concealment of his heresy;

2. a record of Constantine’s baptism that names both the officiant and the place;

3. further notices concerning Arius that are not passed over in silence.

None of these claims fits the surviving Life of Constantine. As is well known, VC never identifies by name the bishop who baptizes Constantine, nor does it specify the baptismal location beyond the suburbs of Nicomedia. Eusebius describes the emperor’s journey to the baths, his prayers in the church of the martyrs, his sense that the time for purification has come, and the summoning of bishops, but the account pointedly declines to name the officiating bishop or to put the word “Arius” into Constantine’s mouth.

Nor does VC “often mention Arius.” Arius appears there only incidentally, and the larger Arian controversy is, by common admission, treated with remarkable reticence relative to the scale of its impact on Constantine’s reign. If the canonical four-book Life is all Photius had, his description of a work that “often mentions Arius” and “states who baptized Constantine and where” is simply wrong.

The most straightforward solution is that Photius is not talking about VC at all in this sentence, but about the Ecclesiastical History in many books that he has just mentioned. On this reading, Photius had before him a Eusebian History whose later books:

– covered the Arian controversy in some detail, with frequent references to Arius and explicit naming of his heresy; and

– included a narrative of Constantine’s baptism in which the officiant and location were given explicitly.

This makes good sense of Philostorgius as well. If Eusebius’ “history” ran into the Constantinian and Arian period, then there was room within the History itself—not just in the separate Life—for an account of Constantine’s baptism and of the Arian controversies surrounding it.

Modern scholarship has sometimes tried to avoid this conclusion by re-attaching Photius’ “in these same books” to the Life of Constantine, treating the phrase as a loose reference to “these Constantinian books” rather than strictly to the Ecclesiastical History. But this sacrifices the natural syntactic reading and does not actually solve the mismatch: the Life still does not frequently mention Arius or name the baptizing bishop. Photius is either (a) conflating several Eusebian works and reading them as one continuous “history,” or (b) reporting accurately on a Eusebian historical text that is no longer identical with what we possess.

The latter option becomes more persuasive once we bring in a later Byzantine reader who had both Photius and some Eusebian text before him and struggled precisely with this mismatch.

3. Zonaras Against Photius’ Eusebius

John Zonaras, writing in the twelfth century after retiring from imperial service to a monastery, compiled a chronicle that heavily depends on earlier ecclesiastical historians. When he comes to Constantine’s reign, he pauses to discuss Eusebius Pamphili. In the Latin paraphrase of his Greek text, he writes that Eusebius, bishop of Caesarea in Palestine, once “embraced Arius’s party” but later withdrew and was received by the Fathers as teaching the Son’s consubstantiality and co-eternity. He notes that “in the Acts, at the beginning, he is first defended as a man of holy life” and that “these things are found written by some,” clearly referring to earlier authorities.

Then Zonaras pivots to his own reading of Eusebius:

“But he himself presents them more ambiguously in his Ecclesiastical History. In these books he is accused of siding with Arius… At the very beginning of the book, while citing David, he himself says—and approves as sound—the words ‘the things that are commanded and created’; and he calls the Father ‘maker,’ as the founder and ruler of the whole universe, who governs with secure dominion; next after him he places the divine Word, to follow the commands of the Father… Not without cause did he write at length—indeed in four books—about his Ecclesiastical History at Nicaea. And he conceals that Constantine the Great, after the conclusions at Nicaea, delayed baptism and was later baptized; he conceals who baptized him. Moreover, he nowhere openly recounts the Arian heresy.”

Several points deserve emphasis.

First, Zonaras hears Photius. His phrase “these things are found written by some” and his mention of “defences” of Eusebius as “a man of holy life” presuppose familiarity with the earlier pro-Eusebian testimonia. His remark that Eusebius “in these books is accused of siding with Arius” is exactly what one would say after reading Athanasius, Jerome, and the hostile anti-Eusebian dossier preserved by later compilers. He takes for granted both the charge of Arianism and the later narrative of partial reconciliation.

Second, and more importantly for our purpose, Zonaras plainly reads Photius’ “in these same books” as referring to the Ecclesiastical History. When he says that Eusebius “himself presents them more ambiguously in his Ecclesiastical History,” he immediately adds: “In these books he is accused of siding with Arius… he nowhere openly recounts the Arian heresy.” Zonaras expects, on the basis of earlier testimony, to find in these books a clear account of Arius and the Arian controversy. What he finds in the Eusebian text available to him is something else: ambiguity, evasion, and silence.

Third, his comments on Constantine’s baptism are a direct answer to Photius. Photius had said that Eusebius “records the baptism of Constantine, stating who baptized him and where.” Zonaras counters: “he conceals that Constantine… delayed baptism and was later baptized; he conceals who baptized him.” Zonaras only writes this because he is reading Photius as claiming that the Eusebian history explicitly names the baptizer and the place. Putting Photius’ statement next to his own copy of Eusebius, he sees that this supposedly explicit information is missing and accuses Eusebius of concealment.

Fourth, the throw-away line that Eusebius “wrote at length—indeed in four books—about his Ecclesiastical History at Nicaea” looks like a clumsy attempt to reconcile Photius’ references to “four books” with the “ecclesiastical history” label. Photius had listed four books On the Praises of Constantine, four books of Life of Constantine, and an Ecclesiastical History in many books. Zonaras seems to conflate these Constantinian materials into a single four-book “ecclesiastical history at Nicaea,” which is precisely the sort of re-arrangement one would expect if he were reading a compressed or altered Eusebian corpus in the light of Photius’ summary.

The upshot is that Zonaras functions as a control reader. He shows us how a Byzantine historian, working with Photius’ Bibliotheca and the Eusebian texts available in the twelfth century, understood codex 127. He assumes that Photius’ “in these same books” refers to a multi-book Ecclesiastical History that contained explicit material about Arius and Constantine’s baptism. He then complains that Eusebius’ Ecclesiastical History—as he has it—is evasive on both points.

If Photius had meant only the Life of Constantine, the whole exchange would make little sense. Zonaras would simply say: “Photius is wrong; Life of Constantine does not say that.” Instead he frames the problem as one of ambiguity and concealment in “his Ecclesiastical History,” which he contrasts with earlier testimonies that attribute more explicit treatment to Eusebius. The easiest explanation is that both Photius and Zonaras believed in a longer, fuller Ecclesiastical History, and that by the time Zonaras wrote, the copies available to him had already lost or suppressed precisely those Constantinian-Arian sections that Photius still presumed.

4. The Arian Profile of Eusebius

The idea that Eusebius might have written an Arian-leaning continuation of his Church History down to Constantine’s death and the accession of his sons would be implausible if the wider tradition portrayed him as a consistent Nicene champion. But the opposite is the case. From the fourth century on, the catholic tradition remembers Eusebius of Caesarea as, at best, a suspect ex-Arian and, at worst, “the most open champion of the impiety of Arius.”

Jerome, in a famous passage in his letter to Pammachius and Oceanus, contrasts Apollinaris and Eusebius and then adds: “Apollinaris wrote exceedingly strong books against Porphyry; Eusebius composed the Ecclesiastical History. But the former introduced a halved Christ, while the latter is the most open champion of the impiety of Arius.” In the Apology against Rufinus, Jerome calls Eusebius “formerly of the Arian party” and states flatly, “in the Catalogue—that is, according to our judgment—he is an Arian.” Elsewhere he describes him as “not a Catholic, but an Arian” and laments that some readers have taken his praise of Origen and his learning as endorsement of his doctrine.

Athanasius names Eusebius among those who initially lent their vote to Arius and later signed the Nicene creed under pressure, only to hedge and equivocate about the key term “consubstantial.” In various anti-Arian synodal documents preserved in the tradition, Eusebius of Caesarea is attacked for double-dealing: he is said to have subscribed at Nicaea and written in favor of the Nicene faith, yet in private letters suggested that the Son was not “of one substance with the Father” and in some places even denied that the Son existed before the Incarnation. Both he and his successor Acacius are treated as pivots of the pro-Arian party in the East.

Epiphanius, in his account of the Meletian schism and the synod of Tyre, presents Eusebius as presiding over a hostile trial of Athanasius and reports the famous outburst of the confessor Potamon, who confronts Eusebius with the question of how he escaped prison and martyrdom in the persecution: “By what means did you escape, unless perhaps you promised to sacrifice—or even sacrificed?” The point is not simply personal cowardice but the implication that Eusebius compromised himself in ways that would later align him with Arius’ “party.”

Later Byzantine authors, drawing on this anti-Eusebian dossier, characterize him in similar terms: he is “bound by an ardent love for the holy martyr Pamphilus,” a prolific and learned historian, yet “in many respects” appears to favor Arius’ opinion. On the other side, pro-Eusebian testimonies, such as Socrates’ discussion in HE 1.8–9, go to great lengths to show that Eusebius, in his doctrinal works (Preparation for the Gospel, Demonstration of the Gospel), confesses the Son as “God from God” and “not one of the things that came into being,” and that his talk of the Son as “created” can be read figuratively, “according to the economy,” rather than literally.

The very existence of such elaborate defences shows that Eusebius’s orthodoxy was a problem that needed defending. Photius, in another codex (15), says he has read two books of Eusebius entitled Refutation and Apology and notes that while his style is prolix, his “prudence and constancy in doctrine do not allow the truth to suffer,” and that in those books he censures blasphemers against the Son and attributes the rise of Arianism to the devil. Internet Archive Even here, however, Photius feels compelled to stress “constancy in doctrine,” a phrase that only makes sense in a context where Eusebius’s doctrinal consistency has been doubted.

If Eusebius was perceived, even by sympathetic readers, as a figure needing doctrinal rehabilitation; if Athanasius and the Egyptian bishops attacked him as a closet Arian; if later popes and councils classified his works as useful but not safe as doctrinal authorities; and if Jerome simply calls him “an Arian”—then it is hardly far-fetched to suppose that a strongly Arian-leaning continuation of his Church History might have been considered unsafe to transmit.

Such a continuation, covering the period from Nicaea to Constantine’s death and the accession of his sons, would have offered an Arian reading of the very events that became the canonical anti-Arian narrative: the councils, the exiles of Athanasius, the recalls of Arius, the internal politics of Constantine’s court, and the questions surrounding his baptism. The ecclesiastical parties who controlled manuscript production in the fifth and sixth centuries had every incentive to prune, revise, or simply omit such material, especially once more orthodox accounts of the same events were available.

5. Reconstruction and Implications

Taken together, Philostorgius, Photius, and Zonaras give us a layered glimpse into a longer Eusebian historical tradition.

At the bottom level, Philostorgius, writing as an Arian historian in the fifth century, says that Eusebius “brought his own history to an end with the succession of the sons of Constantine the Great.” He treats this as a known fact and appeals to Eusebius as an authority even while criticizing his doctrine. In Philostorgius’ world, Eusebius’s History is a continuous narrative that runs into the post-Constantinian Arian controversies and is worth citing on those events.

At the middle level, Photius, in the ninth century, describes an “Ecclesiastical History in many books” that not only covers successions and heresies “down to our own times” but also “often mentions Arius,” “makes no concealment of his heresy,” and “records the baptism of Constantine, stating who baptized him and where.” The most natural reading of his Greek is that all this belongs to the History, not just to the Life of Constantine, and that he has in mind a multi-book historical work in which Constantine’s baptism and Arius’s heresy figure prominently.

At the top level, Zonaras, in the twelfth century, reading Photius and Eusebius together, complains that Eusebius “presents these things more ambiguously in his Ecclesiastical History,” “nowhere openly recounts the Arian heresy,” and “conceals” both Constantine’s delayed baptism and the identity of the bishop who baptized him. His language only makes sense if he expects, from Photius, a History in which these matters are explicit; finding his own text wanting, he attributes the discrepancy to Eusebius’s dissimulation rather than to loss or redaction.

One can, of course, resist the reconstruction and simply blame Philostorgius and Photius for confusion. But this requires us to posit that:

– Philostorgius invented or misremembered an endpoint for Eusebius’s “own history” at the succession of Constantine’s sons, despite being an attentive reader of sources;

– Photius, one of the most sophisticated readers of Greek literature in Byzantium, misdescribed the contents of works he claimed to have read, ascribing to an “ecclesiastical history in many books” material that in fact belongs to a four-book Life of Constantine in which it does not actually appear; and

– Zonaras, reading both Eusebius and Photius, not only failed to notice these obvious errors but built a detailed critique of Eusebius around the mismatch, accusing him of concealment instead of recognizing that Photius was simply wrong.

At some point this becomes special pleading. It is simpler to accept that there once existed a fuller Eusebian historical corpus—whether in the form of an extended Church History, a composite history that absorbed Constantinian material, or a tightly linked set of historical works—that contained more explicit treatment of Arius and Constantine’s baptism than our surviving texts. Over time, that fuller dossier was pruned, rearranged, and supplemented, producing the ten-book Church History, the four-book Life of Constantine, and scattered Constantinian fragments we now possess.

This has implications beyond the internal history of Eusebius’ works. It suggests that the fourth- and fifth-century struggle over the “correct” narrative of the Constantinian turn and the Arian controversy was fought not only in councils and creeds but also on the level of textual transmission. Just as later Latin sources of the ninth century work hard to displace Eusebius’ deathbed-baptism story with a rival legend of Constantine’s early baptism by Pope Sylvester in Rome, in order to buttress Papal primacy and the emperor’s sanctity, so too earlier Greek churchmen may have worked to blunt or efface those parts of Eusebius’ history that could be read as celebrating an Arian triumph.

In that context, Philostorgius’ off-hand remark about the “sons of Constantine” and Photius’ insistence that Eusebius once “recorded who baptized him and where” begin to look like windows into a lost Arianizing extension of the Church History. Zonaras’ bewildered protest—“he conceals these things”—is the protest of a man standing at the far end of a centuries-long process of ecclesiastical editing, with only fragments of the original Eusebian project still visible.

If this reconstruction is even approximately correct, it forces us to rethink how we use Eusebius as a source for the Constantinian age. The text we have is not the whole story but the portion that survived prolonged doctrinal and political vetting. It also provides a neat precedent for later cases—such as the transmission of Clement of Alexandria or the debate over the Letter to Theodore—in which the neat opposition between “authentic” and “forged” may conceal a more complicated history of rewriting, excision, and controlled loss inside the ecclesiastical library itself.