Pelagius (c. 354–c. 418)

A monk from the British Isles

The ancient sources hesitate over the exact origin of Pelagius. Saint Jerome, who fought him fiercely, calls him a "Scot" (Scotus) and mocks his memory, which he claims was dulled by "Scottish porridge" — an expression which, in the Latin vocabulary of the time, actually refers to Ireland, the Scoti then being the inhabitants of the island of Ireland before the migration that would give Scotland its name^[1]. Other contemporary witnesses call him instead Brito, that is, a native of insular Britain — Roman Great Britain, not to be confused with the Armorican peninsula of present-day France^[2]. The very name "Pelagius", the Latinized form of an original that remains uncertain, has sometimes been linked to the Welsh Morgan ("sea-born"), but this link remains a late philological hypothesis, not a documented certainty^[3].

Saint Jerome describes him physically as "tall and corpulent" (grandis et corpulentus)^[4], and all witnesses agree on his learning: he spoke Latin and Greek fluently, knew Scripture and ascetic literature thoroughly, and lived by a demanding rule of life. A notable and rarely stressed fact: although a monk by his way of life, Pelagius was never ordained priest and remained a layman all his life^[5].

Rome, capital of his ascetic influence

Pelagius settled in Rome and remained there, in the testimony of Saint Augustine himself, "for a very long time" (diutissime)^[6] — his arrival can reasonably be dated to the pontificate of Pope Anastasius I (398-401)^[7]. In the capital of the Western Empire, still largely pagan in its aristocracy but swept by a powerful ascetic revival, Pelagius earned a reputation for holiness and moral rigour among cultivated Christian circles, notably senatorial families converted to a demanding Christianity.

It was in Rome that he composed, before the sack of the city by Alaric in 410, his Commentaries on the Epistles of Saint Paul (Commentarii in Epistolas Sancti Pauli), a work already known to Saint Augustine by 412^[8]. His teaching spread there in the form of practical maxims of moral exigency, whose insistence on personal responsibility and the real possibility of living a holy life won over a Christian elite anxious about the loosening of morals.

Caelestius, the disciple who systematizes the doctrine

In Rome, Pelagius met Caelestius, a lawyer probably of Italian origin, converted to the ascetic life^[9]. Caelestius became his close collaborator and turned Pelagius's "practical maxims" into a far sharper theoretical system, particularly on the question of original sin, which he came to deny explicitly as transmitted by generation^[10]. And it was Caelestius, not Pelagius himself, who would be the first condemned by name — a fact often blurred although it illuminates all that follows: the master preached an ambiguous moral exigency, but it was the disciple who drew its most radical dogmatic consequences.

Man can, by his will alone, avoid sin

Pelagius himself sums up his method of teaching in his Letter to Demetrias, addressed in 413-414 to a young Roman virgin of high birth who had just consecrated herself to God:

"Whenever I have to speak of moral instruction and the conduct of a holy life, it is my custom first to show the power and quality of human nature, and to make plain what it is capable of accomplishing." — Pelagius, Letter to Demetrias, ch. 2^[11]

The programme is clear: before any precept, establish that man possesses in himself, by his created good nature, the sufficient capacity to accomplish the good. Pelagius stresses this point elsewhere in the same letter:

"No one knows better the measure of our strength than He who gave us our strength; and no one understands better what lies in our power than He who endowed us with the very power to act." — Pelagius, Letter to Demetrias, ch. 16^[12]

"He has not willed to command the impossible, for He is righteous; and He will not condemn a man for what he could not avoid, for He is holy." — Pelagius, Letter to Demetrias, ch. 16^[13]

The argument has a seductive logical coherence: God, being just, cannot command something impossible; yet He commands the perfect observance of the law; therefore this observance is genuinely possible to human nature alone. Saint Augustine sums up thus, in his treatise On Nature and Grace, the technical formula by which Pelagius distinguished three elements in every moral act:

"He distinguishes three things […] : ability, will, action (posse, velle, esse). Ability comes from God alone; will and action are from man alone." — reported by Saint Augustine, On the Grace of Christ, I, 4-5^[14]

A grace reduced to outward help

For Pelagius, grace truly exists — he would always defend himself against being an adversary of grace — but it is limited to outward aids: the revelation of the law, the example and teaching of Christ, the forgiveness of past sins in baptism, the enlightenment of the intelligence by Scripture. What his doctrine refuses is an interior help, a supernatural motion of the will itself, distinct from natural free will. This distinction, technical in appearance, stakes everything: if grace is only an outward aid to an already sufficient capacity, man has no absolute need of it to act well — it merely makes the task easier.

Original sin denied or emptied of meaning

On the question of original sin, Caelestius goes further than his master and explicitly denies any transmission by generation: Adam, he says, would have been created mortal anyway, and his sin harmed only himself, not his descendants^[15]. Children would therefore be born in the very state in which Adam stood before his fall, and the baptism of little children could no longer be justified as the remission of an inherited sin but only as access to a higher good — a position the African councils would judge incompatible with the universal practice of baptism "for the remission of sins", including for infants^[16].

What was really at stake: the necessity of Christ the Saviour

Beneath an appearance of rigorous moral exigency, Pelagianism in reality empties the Cross of its radical necessity. If man can, by his nature alone, avoid sin and merit salvation, Christ becomes an admirable model and a teacher of morals, no longer the Saviour without whom none can be saved. This is the point Saint Augustine would never cease to hammer home: the controversy is not first a quarrel of theologians over a technical point; it touches the very heart of the Gospel — is redeeming grace an absolute necessity, or a mere optional supplement?

The sack of Rome by Alaric in 410 scattered the capital's ascetic circles. Pelagius and Caelestius left the city for North Africa^[17]. Pelagius soon continued on his way to Palestine, while Caelestius lingered at Carthage, where he sought ordination to the priesthood.

The first trial of Caelestius (411)

It was on this occasion that Caelestius was denounced for his theses on original sin before a synod gathered at Carthage in 411, under the presidency of Bishop Aurelius. Six propositions drawn from his teaching were condemned; ordered to retract, Caelestius refused, holding that the question of the transmission of Adam's sin remained an "open question" on which the Church had not pronounced^[18]. This first trial, directed against the disciple and not the master, set the whole Pelagian affair in motion.

Pelagius in Palestine: the synod of Diospolis (December 415)

Settled in Palestine, Pelagius at first enjoyed relative protection, notably from Bishop John of Jerusalem. But the affair caught up with him: in December 415, a synod of fourteen bishops met at Diospolis (ancient Lydda) to examine his positions^[19]. The principal accusers did not appear before the synod; Pelagius, questioned, framed his answers prudently and ambiguously, even formally condemning, for the occasion, certain propositions attributed to Caelestius without ever admitting they were his own. The synod, ill-informed of the exact substance of the debate already agitating Africa, declared him worthy of remaining in communion with the Church^[20].

Saint Augustine himself, who was not present, would shortly afterwards write a detailed and critical account of this synod in his treatise On the Proceedings of Pelagius (De gestis Pelagii, 417), where he shows that the acquittal of Diospolis rested on skilful but equivocal answers, not on any genuine adherence of Pelagius to the Catholic doctrine of grace^[21].

The Doctor of Grace enters the lists

It was against Pelagius that Saint Augustine of Hippo (354-430) deployed the bulk of his mature theology of grace, which would earn him the title of Doctor gratiae, the "Doctor of Grace". Himself converted by a grace he felt as irresistible — the famous "Tolle, lege" of the Milan garden — Augustine knew from experience that the human will left to itself remains captive to sin and is freed only when touched from above. As early as 412, he published On the Merit and Remission of Sins and On the Spirit and the Letter, two treatises that already answered, without naming him directly, the theses then circulating in Rome^[22].

In 415, he published On Nature and Grace (De natura et gratia), a direct point-by-point refutation of Pelagius's lost treatise entitled De Natura, in which Augustine quotes his adversary abundantly the better to refute him^[23]. Pelagius's lost treatise is today known only through these quotations by Augustine — a frequent fate for the writings of condemned authors of late Antiquity, whose original works have often vanished and survive only as fragments preserved by their refuters.

"What shall I say of this vain and false boasting with which our poor human nature prides itself, believing it can suffice of itself for every virtue?" — Saint Augustine, On Nature and Grace, LXVIII^[24]

After the equivocal synod of Diospolis, Augustine published On the Perfection of Human Righteousness (414-415) and then, once the African and Roman condemnations were obtained, On the Grace of Christ and on Original Sin (418), where he methodically analyses Pelagius's posse-velle-esse formula^[25], and finally the six books Against Julian (421-422), directed against Julian of Eclanum, the Italian bishop who became the most intellectually formidable defender of Pelagianism after the disappearance of Pelagius^[26].

Jerome and the "Scottish porridge" polemic

Saint Jerome (c. 347-420), retired at Bethlehem, also entered the lists against Pelagius, with a fierceness of style contrasting with Augustine's methodical rigour. Around 415, answering one Ctesiphon troubled by the progress of Pelagianism, he composed his Letter 133, in which he traces Pelagius's theses back to Stoic philosophies and to ancient heresies such as Manichaeism and Priscillianism^[27]. He also wrote, in 415, a Dialogue against the Pelagians in three books, in the form of a dispute between a Catholic and a heretic^[28].

Yet it is in the prefaces of his Commentary on Jeremiah, written between 415 and 419, that Jerome delivers his most personal attacks, mocking the "Scottish" (that is, Irish) origin of Pelagius and his memory supposedly dulled by coarse food:

"He has on his side the offspring of the Scottish race, from the neighbourhood of the Britons, his mind dulled by Scottish porridge." — Saint Jerome, Commentaries on Jeremiah, prologues, between 415 and 419^[29]

This sharp trait, still famous in modern historiography, illustrates the personal tone ancient polemic often takes — without weakening the soundness of the doctrinal arguments developed elsewhere, notably by Augustine.

Carthage and Milevis (416): Africa united against Pelagius

In 416, two distinct synods gathered in Africa — one at Carthage bringing together sixty-seven bishops, the other at Milevis bringing together fifty-nine — jointly condemned the doctrines of Pelagius and Caelestius as contrary to the Catholic faith and informed Pope Saint Innocent I of this by solemn synodal letters^[30].

Pope Saint Innocent I confirms (27 January 417)

By three separate letters dated 27 January 417, Pope Saint Innocent I answered the African bishops and confirmed their condemnation, excluding Pelagius and Caelestius from the communion of the Church "until they come to repentance" (donec resipiscant)^[31]. This was the first explicit pontifical sentence against the Pelagian affair — but Innocent I died shortly afterwards, in March 417, before the affair was definitively settled.

Pope Saint Zosimus hesitates, then thinks better (417-418)

The new pope, Saint Zosimus, at first showed himself favourable to Pelagius and Caelestius. The latter came in person to present to Zosimus, in the church of Saint Clement in Rome, a Libellus fidei — an exposition of his faith drafted in prudent terms — which the pope examined at length without finding manifest heresy in it; Zosimus then granted the African accusers a delay of two months to appear and press their grievances^[32]. This initial hesitation of Rome, today well documented by modern historiography, shows that the affair was not as clear-cut to contemporaries as it appears to us in retrospect.

The rescript of Emperor Honorius (30 April 418)

The African episcopate, informed of Zosimus's favourable reversal, reacted firmly and prepared a new council at Carthage. But the decisive turn came first from imperial authority: on 30 April 418, Emperor Honorius promulgated a rescript condemning Pelagius, Caelestius and their partisans as disturbers of the public peace and ordering their banishment from Rome^[33].

The Council of Carthage of 1 May 418: eight canons that carry authority

Under the double pressure of the imperial rescript and the synodal letter of the African bishops, Pope Zosimus thought better of it entirely and addressed to all the bishops of the world a circular letter, the Epistula Tractoria, categorically demanding the condemnation of Pelagianism as heresy — a text today lost in its entirety and known only through fragments quoted by other ancient authors^[34]. The same day, the Council of Carthage, bringing together some two hundred bishops, formulated eight canons that would become the Catholic doctrinal charter of grace and original sin for the centuries to come:

Council of Carthage, 1 May 418, eight canons against Pelagianism. Text in Denzinger, Enchiridion Symbolorum, 10th ed., 1908, nos. 101-108^[35].

Convened first to judge the Christological error of Nestorius, the Ecumenical Council of Ephesus took the opportunity of its meeting solemnly to endorse, in 431, the condemnations already pronounced by Rome and Africa against Pelagianism^[36]. The connection is not merely circumstantial: Caelestius, driven from the West after 418, had found refuge with Nestorius at Constantinople, seeking the patriarch's support against his own condemnations^[37]. By condemning together, in the same conciliar movement, the one who denied the full reality of the Incarnation of the Word and those who denied the radical necessity of the grace that this Incarnation comes to bring, the Church manifested the profound coherence of her faith: it is because the Word truly became flesh to save us that no human will, however virtuous, can save itself. See the Council of Ephesus (431) for the detail of this session and of the Nestorian crisis that directly occasioned it.

History loses track of Pelagius himself shortly after his condemnation. The last documented mention concerns him in the summer of 418, when he was still corresponding with the Roman couple Pinian and Melania the Younger, then settled in Palestine^[38]. After that date, no source tells us what became of him: neither the place nor the date of his death is known with certainty, and the most commonly retained hypothesis — without decisive documentary proof — is that he died in the East, in Palestine or Egypt, in the years following his condemnation^[39].

Caelestius, by contrast, keeps appearing in the sources: reappearing in Rome in 417 during the brief favourable period of Pope Zosimus, he was exiled anew in 421 and then in 425, before seeking refuge in the East with Nestorius around 429. His last documented mention dates from that year 429; afterwards, "all trace of him is lost"^[40].

John Cassian and the question of the first step

The fight against Pelagius did not close the debate on grace. In the following decades, several monks of southern Gaul, including John Cassian, while firmly rejecting Pelagianism, hesitated on one precise point: does the very first movement toward conversion come from man, whom grace would then come to second? This intermediate position, which history would later call "semi-Pelagianism", was vigorously combated by Saint Prosper of Aquitaine, faithful disciple of Augustine, before being definitively settled by the Second Council of Orange in 529, which affirms that even the beginning of faith is a gift of prevenient grace^[41]. For the detail of this doctrine and its present scope, see What is actual grace? and the article devoted to Saint Prosper of Aquitaine.

Modern resurgences of a permanent temptation

The Council of Trent would in turn take up, against certain humanist readings of the Renaissance, the affirmation of the absolute necessity of grace, while modern theology continues to detect, in secularized forms, the same Pelagian temptation: the idea that man saves, perfects or justifies himself by his own resources alone — moral, psychological or spiritual — without structurally needing a help that comes from beyond himself. Pope Francis explicitly warned against a contemporary "neo-Pelagianism", taking the form of excessive trust in one's own strength, merits or observances, to the detriment of the freeness of grace^[42].

Peter Brown and B. R. Rees: a sincere ascetic, not a cynic

From the mid-20th century onwards, several historians proposed a more nuanced reading of the figure of Pelagius. The British historian Peter Brown, in an article that remains classic, Pelagius and his Supporters: Aims and Environment, places the Pelagian movement in the social context of the Christianized Roman aristocracy of the early 5th century, in quest of a demanding asceticism and sincere moral reform rather than a calculated heresy^[43]. The Welsh patristic scholar B. R. Rees, in his monograph Pelagius: A Reluctant Heretic, goes the same way: Pelagius appears there as a rigorous moralist, sincerely concerned with personal holiness, rather than a systematic theologian consciously building a heresy^[44].

What this reassessment changes — and does not change — in the judgment of the Church

This historiographical reassessment concerns the psychology and intentions of Pelagius, not the doctrinal content of his teaching, which the Church judged and continues to judge incompatible with revealed faith. A man may be sincere, ascetic and animated by genuine moral zeal while professing an objective error with grave consequences: to deny the interior necessity of grace amounts, whether one wills it or not, to playing down the radical necessity of Christ the Saviour. The subjective sincerity of Pelagius — which modern historiography today renders more credible — therefore in no way annuls the rightness of his objective condemnation by Carthage, by Rome and by Ephesus: it merely clarifies its human terms, without changing its doctrinal substance.

The Pelagian affair is inseparable from the Augustinian theology of grace and from the great doctrinal controversies of the early Christian centuries which, each in its own way, put at stake the true nature of Christ or the true necessity of His redemptive work.

• On the great adversary of Pelagius and the Catholic theology of grace: Saint Augustine of Hippo and what is actual grace?.
• On original sin and its foundations: did the Garden of Eden and original sin really exist?.
• On the second great anti-Pelagian polemicist: Saint Jerome.
• On semi-Pelagianism and its refutation: Saint Prosper of Aquitaine.
• On the other great heresies of the early Christian centuries: Arius, Nestorius and Marcion of Sinope.
• On the council that solemnly condemned Pelagianism alongside Nestorianism: the Council of Ephesus (431).