For seven centuries the names of Thomas Aquinas and Gregory Palamas have functioned in popular polemics as twin banners of irreconcilable confessional armies. To be Catholic, on this telling, is to confess God as actus purus essendi — the simple act of being whose essence is identical with His existence; to be Orthodox is to confess God as essence and energies, an unknowable ousia communicating itself through really distinct uncreated energeiai. The Latin tradition climaxes in the visio essentiae Dei; the Byzantine tradition in the vision of the uncreated Taboric light — and never the twain shall meet.

This framing almost guarantees a dead end. It presupposes that both men were trying to answer the same philosophical question with the same conceptual vocabulary and produced incompatible answers. That presupposition is now in serious historical doubt. A more productive question is this: when Aquinas describes God as the unparticipated esse in which the saints participate by lumen gloriae, and when Palamas describes God as essence inaccessible and energies participable, are they describing the same theotic reality in two different philosophical grammars?

If they are, then the apparent contradiction is largely a translation problem rather than a doctrinal one — and the Eastern Catholic Churches, which venerate Palamas as a saint while remaining in communion with the See of Peter, are not theological oxymorons but the lived institutional answer to a question Latin and Byzantine theologians spent centuries asking past each other.

I. A Discovery in the Translator’s Study

The decisive philological datum was identified by Fr Christiaan Kappes, a Byzantine Catholic priest who serves as Academic Dean and Professor of Liturgical and Dogmatic Theology at the Byzantine Catholic Seminary of SS. Cyril and Methodius in Pittsburgh, working in conversation with John A. Demetracopoulos of the University of Patras.

In the 1350s, the Byzantine humanist and statesman Demetrios Kydones undertook what was then an extraordinary intellectual project: translating the Summa theologiae of Thomas Aquinas into Greek. Kydones was no mere copyist. He was the most accomplished Byzantine Greek of his generation, a first-rate theologian who had already translated the Summa contra Gentiles (completed December 1355) and whose work brought Aquinas directly into the Greek-speaking intellectual world for the first time.

Aquinas’s technical Latin phrase actus essendi — the “act of being,” the most fundamental and perfective principle Thomas attributes to God and by which He gives being to all that is — had no obvious Greek equivalent. Kydones rendered it hē tou einai energeia — “the energy of being.” The word he reached for was energeia: the very word at the centre of the Palamite controversy that had been raging in Constantinople for a generation.

This was not a blunder. Kydones was too careful for that. It was recognition. Kappes has developed this thesis across a substantial body of work, including his doctoral dissertation at the Aristotle University of Thessaloniki (2015) on the theology of George-Gennadios Scholarios, his monograph The Immaculate Conception (Academy of the Immaculate, 2014), and The Epiclesis Debate at the Council of Florence (Notre Dame, 2019). The philological finding is documented most accessibly in Demetracopoulos’s foundational essay “Palamas Transformed” in Greeks, Latins, and Intellectual History 1204–1500 (Peeters, 2011).

The implication reaches further than philology. Palamas himself — contrary to the standard narrative — was working in a world already shaped by translated Latin scholasticism. His mature writings show engagement with thirteenth-century Latin theological methodology, and his most important theological heirs would explicitly use Latin scholastic categories to defend his teaching. The supposed civilizational gulf between Latin rationalism and Greek mysticism was not a fourteenth-century reality. It was, as Norman Russell’s magisterial Gregory Palamas and the Making of Palamism in the Modern Age (Oxford University Press, 2019) demonstrates, largely a twentieth-century construction — the joint product of Martin Jugie’s hostile Thomism and the polemical neo-Palamism of Lossky and early Meyendorff.

II. Aquinas on Deification: Solus Deus Deificat

The objection that Aquinas has no doctrine of deification — that the Latin tradition lost the patristic vocabulary of theosis somewhere between Augustine and the high Middle Ages — was the operating premise of much twentieth-century neo-Palamism. It does not survive contact with Aquinas’s actual text.

The watershed scholarly correction was Anna Williams’s The Ground of Union: Deification in Aquinas and Palamas (Oxford University Press, 1999), which argued in meticulous detail that deification is not a marginal motif in Aquinas but a structural centre that organises his soteriology and is architecturally parallel to the Palamite account. Williams’s specific theses have been refined and in places contested by subsequent scholarship — Richard Cross raised important questions in Journal of Theological Studies 69 (2018), and Luke Martin in New Blackfriars 98 (2017) — but her core finding has become a settled point of contemporary scholarship. Marcus Plested’s Orthodox Readings of Aquinas (Oxford University Press, 2012) reinforces the picture from the other direction, tracing Aquinas’s enthusiastic reception in the Byzantine world.

The principal Thomistic loci are well known once one knows to look for them. ST I-II, q. 110, a. 1 defines grace as participatio divinae naturae, citing 2 Peter 1:4 directly. ST I, q. 43 teaches that in sanctifying grace the Trinity does not merely produce created effects but gives Itself: “the divine person Himself is given,” dwelling in the soul “as the known in the knower and the beloved in the lover.” ST III, q. 1, a. 2 gives the Christological architecture: ut hominem faceret deum, that He might make man God — citing Athanasius directly and repeating the patristic admirabile commercium that both Latin and Byzantine theology share as common inheritance.

The secondary scholarship now consolidates this decisively. Jared Ortiz’s edited volume Deification in the Latin Patristic Tradition (CUA Press, 2019) demonstrates that the deification motif runs from Tertullian to the high medieval West without interruption, killing the narrative of a Latin lacuna. David Meconi’s The One Christ (CUA Press, 2013) establishes the Augustinian foundation. Aquinas’s constant use of Pseudo-Dionysius means that the apophatic tradition central to Eastern hesychasm is also central to the Latin Doctor Communis.

III. The Eastern Catholic Witness

If Aquinas and Palamas are saying recognizably the same thing in different grammars, this is not merely an academic claim. There exists, and has existed for centuries, a community of Christians who venerate both — in full communion with the Bishop of Rome and with a liturgical and dogmatic tradition rooted in Byzantium. The Eastern Catholic Churches are the lived institutional answer to the question.

The Melkite witness is the sharpest. In 1971, the Holy Synod of the Melkite Greek Catholic Church at Ain Traz formally restored the commemoration and Office of St Gregory Palamas on the Second Sunday of Lent to the Triodion — reversing earlier latinizing reforms. This was not done unilaterally. The decision was submitted to the Sacred Congregation for the Doctrine of the Faith; no objection was raised. Patriarch Maximos V Hakim communicated the Synod’s decision to Cardinal Franjo Šeper, Prefect of the CDF, in a letter of 29 August 1971.

John Paul II gave this the highest magisterial framing. Orientale Lumen (2 May 1995) urges Latin Catholics to “avail themselves more often of the spiritual riches of the Eastern fathers.” In his General Audience of 12 November 1997, he listed Palamas alongside Nicholas Cabasilas and Gennadios Scholarios as “great theological writers” of the Christian East. The Ukrainian Greek Catholic tradition has lived this question from within. At the Byzantine Catholic Seminary in Pittsburgh, Fr Kappes’s own institution, the question is not “can we hold Palamas in communion with Rome?” but “how precisely do Palamas and Aquinas converge?”

IV. The Formal Distinction: Where Two Grammars Can Meet

Where do the grammars actually diverge? Honestly: at the metaphysics of distinction. The entire question of whether Palamas and Aquinas can be reconciled turns on what kind of distinction one places between God’s essence and His self-communication to creatures.

And this is not a modern proposal — it is the path taken by Palamas’s own most authoritative heirs. John VI Kantakouzenos (d. 1383), Mark of Ephesus (d. 1444), and above all George Gennadios Scholarios (d. ca. 1472) all read the Palamite distinction as kat’ epinoian — a conceptual distinction with foundation in the thing, functionally equivalent to Scotus’s formal distinction.

The neo-Palamite claim that Palamas requires a distinctio realis in the strong compositional sense is, on the historical evidence, not the claim of Palamas’s most learned heirs. It is a twentieth-century theological move. Norman Russell’s 2019 study makes this case at book length: the “Palamism” constructed in opposition to Western theology is largely a twentieth-century invention, and when freed from this construction, Palamas’s theology is capable of fruitful use by contemporary theologians without the need to subscribe to what has been regarded as “Palamism.”

V. Two Grammars, One Fire

What would genuine convergence actually look like? It would look like six honest recognitions, none of which requires either tradition to surrender its genuine insights.

First: both traditions confess the same theotic reality. God is utterly transcendent and unknowable in His essence. He is also genuinely, ontologically communicative — He gives Himself to the rational creature elevated to behold and participate in Him. Aquinas calls the creature’s term visio beatifica by lumen gloriae; Palamas calls it the vision of the uncreated light. The architecture is the same.

Second: both traditions ground theosis in the Incarnation. Aquinas’s ut hominem faceret deum and Palamas’s insistence that “in Christ the divinity dwells bodily” are different vocalizations of the same patristic admirabile commercium.

Third: both traditions require some metaphysical account of how the infinite God becomes genuinely accessible to the finite creature. The Scotist formal distinction, embraced by Mark of Ephesus and Scholarios, provides a coherent grammar for both.

Fourth: both traditions must hold together transcendence and genuine participation. Pseudo-Dionysius, shared by both, insists on both terms simultaneously.

Fifth: the formal ecumenical dialogue has slowly recognized this. Ut Unum Sint (1995), §54, calls explicitly for examination of how far various theological formulations express the same faith in different idioms.

Sixth: the historical record refutes the ideological construction. Kydones renders actus essendi as hē tou einai energeia. Nicholas Cabasilas draws on Aquinas. Mark of Ephesus argues the Palamite case at Florence with the Scotist formal distinction. Scholarios produces Greek translations of Aquinas while defending Palamas. These are the actions of men who thought they were working on the same problem with tools drawn from both sides of a sea.