Much attention has been given over the last half century to the war of attrition waged against Augustine's distinctive doctrines of original sin and predestination by Julian of Eclanum, notably in studies by Peter Brown and Josef Lössl.Footnote ¹ That controversy can be seen at its deepest level as a struggle between an older and a newer understanding of man's place in the Christian scheme of salvation in which Augustine challenged an earlier, more conservative, view of the freedom of the human will and man's ability to respond to God's grace. It is not surprising therefore, that the oscillation of Pope Zosimus, first overturning the condemnation of Pelagius and then endorsing it, led to Julian's rebellion, backed by eighteen other Italian bishops. They refused to accept what they saw as a coup by the African Churches supported by the imperial court. Nor is it surprising that even those who accepted Rome's ruling continued to show sympathy for those conservative Italian Christians who contested Augustine's darker view of man. Among such sympathisers were Paulinus of NolaFootnote ² and others who spoke up for the returning exiles of Julian's party in the Rome of Leo i,Footnote ³ against whom the author of the Epistola ad Demetriadem wrote during the same pontificate.Footnote ⁴

The continuing attempt to limit the influence of Augustine's teachings on these issues after his death in 430 by opponents from within Italy has attracted less attention.Footnote ⁵ Instead, research has focussed on the Gallic monastic opponents of predestination, led initially by Cassian, and their anti-predestinarian but unimpeachably orthodox critique of extreme Augustinian teaching in this field which the popes of the fifth century from Celestine onwards resolutely refused to condemn. Only in the sixth century did Caesarius of Arles, with papal backing, overrule the alternative understanding of grace and free will which the monks of southern Gaul held in opposition to that of Augustine.Footnote ⁶

The anti-predestinarian opposition kept up by Julian's party and the mysterious figure known as Arnobius the Younger, all apparently operating in Italy after Julian's abortive attempt at restoration to his see and reconciliation with the Roman Church in 439, has often been neglected. Part of the reason for the lack of progress lies in the disagreements over which works can be attributed to these figures. There is now a body of material which can be assigned to Julian of Eclanum's authorship with some certainty.Footnote ⁷ But Dom Germain Morin constructed a whole corpus of material which he attributed to Arnobius, the named author of the Commentarii in Psalmos. Morin believed that it included the Praedestinatus, Liber ad Gregoriam, Conflictus Arnobii Catholici cum Serapione and Expositiunculae in Evangelium.Footnote ⁸ The case was based essentially on grounds of style and linguistic analysis, out of which he constructed a biography of a supposed single author. Arnobius was portrayed as an exiled African monk living in the Rome of Leo i.Footnote ⁹ The Corpus Christianorum has published these works under his name, but the matter remains far from settled.Footnote ¹⁰ One work was certainly written by someone else. Lukas Dorfbauer has recently demolished the case that the compiler of the Expositiunculae is identifiable with the writer of the Commentarii by demonstrating that the former work cannot date from much before the seventh century.Footnote ¹¹ More radically, he has also questioned whether any of the other works that Morin assigned to the Arnobius mentioned in the Commentarii emanate from the same pen.Footnote ¹²

While there is undoubtedly scope for debate around the Conflictus and the Liber ad Gregoriam,Footnote ¹³ Dorfbauer is unjustifiably sceptical about the Praedestinatus. In particular, he fails to consider the fact that, aside from echoes of style and language, Francis Gumerlock has argued that the Commentarii and the Praedestinatus mount a sustained attack on an individual named as the ‘predestined one’, and that this individual is none other than the leading champion of Augustine's thorough-going predestinarian views, Prosper of Aquitaine himself. Gumerlock has pinpointed Prosper as the target of attack in the Praedestinatus on the basis of distinctive characteristics exhibited by the Aquitanian theologian.Footnote ¹⁴ Prosper, in turn, replies to the specific attacks on predestination in the Commentarii, and the accusations against him of heresy, in his Expositio psalmorum. Footnote ¹⁵ Crucially, the writer of both the Commentarii and Praedestinatus portrays himself in each of these works as under attack from a single adversary who accuses him of holding Pelagian tenets.Footnote ¹⁶ These unorthodox doctrines he angrily proceeds to anathematise, namely that man can be without sin, if he wants to be, even without God's assistance, and that death did not come through Adam and life through Christ.Footnote ¹⁷ It is stretching credibility to suggest that the highly personalised terms of this debate, involving an insulting reference to a ‘predestined one’ which is not found anywhere else, and featuring exchanges between individual leaders from the pro- and anti-predestinarian camps respectively,Footnote ¹⁸ addressing each other in the second person singular, can have involved two separate authors of the Commentarii and Praedestinatus ranged against Prosper. The Commentarii itself refers to another work by the same author, an alienum opus, and to an aliud propositum, and has clear links with the Praedestinatus, as the critical apparatus to the editions of Daur and Gori demonstrate.Footnote ¹⁹ The framework and characteristics of the debate are the same in both texts. The two works are marked by reference to heated exchanges which were absent from the more measured controversy between Prosper and the monks of southern Gaul. Furthermore, the author of the Praedestinatus refers to the fact that only two or three little men with blind hearts follow the extreme formulation of the doctrine of predestination, which appears to be a reference to Prosper, his associate Hilary and possibly the Rufinus who wrote to Augustine.Footnote ²⁰ While works should not be brought unnecessarily under the umbrella of individual authors without good cause, neither should they be separated unjustifiably when there are such strong common bonds.

Francis Gumerlock makes a very convincing case that the profile of Arnobius’ opponent in these two works fits Prosper's own. The unnamed adversary believes that predestination is an essential element of the catholic faith, he is characterised as trying to project an irenic attitude, he displays a propensity to argue by reference to ecclesiastical authority rather than relying solely on theological arguments and he makes a distinction between general and special grace.Footnote ²¹ That distinction was Prosper's particular contribution to the debate over grace and free will.Footnote ²² But the identification of this opponent raises another question: who was Arnobius himself? Until recently, scholars have tended to accept the contention of Morin, who first sought to chart the extent of Arnobius’ literary corpus, that the figure in question was an exiled African monk who had fled from the Vandal invasion and subsequently lived in Rome from the 430s until the era of the Council of Ephesus in 451. The older hypothesis of Hans von Schubert, suggesting that part at least of the anonymous work Praedestinatus should be ascribed to Julian, has essentially been abandoned,Footnote ²³ although Michael McHugh noted that the Praedestinatus might still have emanated from Julian's circle.Footnote ²⁴ Gumerlock's work in fact provides important new clues to the figure currently labelled Arnobius the Younger, defined here as the author of the Commentarii and Praedestinatus, and that a closer reading of these two works and an understanding of his relationship with Prosper offer a good chance of establishing his identity.

In the first place, it can be shown that Morin's hypothesis of an African origin for Arnobius is built on shaky foundations. Indeed, Morin initially believed that the author of these works was a Gallic or Illyrian figure.Footnote ²⁵ Later he built an elaborate case, depending entirely on internal evidence from these attributed texts, that Arnobius was an African monk who later lived in Rome based on the fact that Arnobius is a name not found outside Africa; that the individuals to whom the Commentarii in Psalmos is dedicated, Laurentius and Rusticus, are two bishops from Mauretania Caesariensis who appeared at African councils during the first third of the fifth century; that he refers to himself as a nonnus or aged monk and to other brethren; and that he shows a knowledge of the African Bible and liturgy, but also of the liturgy of the Roman Church and the passiones of fifth-century Roman and neighbouring saints.Footnote ²⁶

Lukas Dorfbauer has already shown that Morin's view of Arnobius as the author of contemporary passiones is no longer sustainable and has questioned the tenability of his other biographical suppositions.Footnote ²⁷ More fundamentally, Morin assumes that the supposedly personal information in these works is accurate and not fictional. But even if the other doubtful works which he attributed to Arnobius are accepted as authentic, and interpreted literally, the identification of the writer as an African monk is flawed. In the Conflictus, the author adopts the persona of a defender of the Roman (apostolic) see and its Christological teaching during the era of the Council of Chalcedon (451) in the course of public debates against an Egyptian opponent, Serapion, who championed Alexandrian theology against the doctrinal position adopted at the council, itself based on Leo i’s Tome. But no such debates, nor the appointment of a champion of papal doctrine, could have taken place in Rome itself without express papal sanction, and any policy of allowing open and free discussion of condemned teachings before nominated judges does not tally with Leo's vigorous attempt to counter and suppress the ‘Eutychian’ views put forward in his city by Egyptian merchants, as is revealed by a sermon delivered in their quarter.Footnote ²⁸ The debate is a contrived and imaginary set-piece aimed at the intellectual discomfiture of Rome's theological opponents. As such it can provide no reliable biographical information about the author or his precise place of residence. The Liber ad Gregoriam, for its part, privileges marriage in a way that no fifth-century ascetic in the post-Augustinian era could easily have done. By then, the nuptial union between Christians had come to be considered as no more than a second best way of life. The work is a pronounced vindication of the need for the wife's endurance within the married life of Christians and the evils which may result if the addressee seeks to avoid conjugal relations with her husband. It hardly represents a contemporary monastic, as opposed to a pastoral, perspective. Morin's picture of Arnobius, built from these self-contradictory materials, begins to implode.

In addition to such inconsistencies, there is absolutely no trace of a historical figure named Arnobius in any of the literature or biographical works of the fifth century; in particular he does not appear in Gennadius’ De viris illustribus. Nor is there any note of his works in the later review by Photius of the contents of his library. This should put us on guard. The editors of the Prosopographie chrétienne have already cast doubt on the African origins of Bishops Rusticus and Laurentius,Footnote ²⁹ but it is no more certain that they were Italian bishops as opposed to fictional figures. If we are to pinpoint the identity of Arnobius, the writer of the two core works which seem to come from his pen, we need to attend to the circumstances of his clash with Prosper of Aquitaine, which Gumerlock has ably explored, and to determine when this clash might have taken place.

In the Commentarii in Psalmos and Praedestinatus, the author crosses swords with Prosper of Aquitaine, the chief champion of Augustine's most extreme predestinarian views after 430, until Prosper moderated his position at the end of his life.Footnote ³⁰ There seems to have been some sort of personal duel between them in which the so-called Arnobius appears as a leader and spokesman for an anti-predestinarian party, disputing the validity of Augustine's views through exegesis of the Psalms and key Pauline texts. Chief among these was Romans viii.32, which emphasised that Christ died to save all men.Footnote ³¹ Arnobius appears in the context of a formal debate between pro- and anti-predestinarian parties. In this debate, Prosper was challenged over his interpretation of St Paul's teaching that ‘Those whom he predestined, those he called.’ The Aquitanian theologian argued that the proposition referred only to God's elect, whereas his opponent pointed out that a subsequent verse made it clear that Christ was given up for all, not just those predestined for salvation. The writer accuses his predestinarian opponent, namely Prosper, of closing the book (presumably his Bible or catena of biblical texts) and shouting that ‘God does not call all to his grace; he does not call all’, thereby stunning and troubling his opponents by going beyond what any of the predestinarian ‘heretics’ had ever said before.Footnote ³²

Gumerlock suggests that the altercation happened in 431. He places the conference at the point when Prosper appeared in Rome before Celestine i to seek papal endorsement of Augustine's predestinarian teaching against the criticisms circulating within monastic circles in Marseilles.Footnote ³³ But this does not seem to be a likely scenario. The first-hand account of the episode given in Celestine's subsequent letter to the Gallic bishops, Apostolici verba, praising Augustine as a pillar of orthodoxy, but refusing to endorse his more advanced views, omits any mention of a debate between different groups in Rome. It simply refers to the presence of Prosper and his ally Hilary in bringing an appeal against the criticism of Augustine by Cassian and the monks of southern Gaul.Footnote ³⁴ Arnobius’ exchanges with his opponent do not fit easily into this controversy. Prosper had not articulated his doctrine of special grace in any of his works from the early 430s against Cassian's followers. It is alluded to briefly in the Praeteritorum, generally dated to the late 430s or early 440s, and perhaps directed at Julian and his followers in 439 if a recent study is correct.Footnote ³⁵ The doctrine is fully worked out only in his De vocatione which dates from the pontificate of Leo i.Footnote ³⁶

The Praedestinatus is securely placed by Gori between 432 and 449: after the death of Celestine but before the Eutychian controversy.Footnote ³⁷ Within this window there is no direct surviving evidence of a conference anywhere at which the issues of predestination and special grace might have been discussed. The pursuit of this line of enquiry leads to a dead end. The indication of a personal duel between Prosper and an anti-predestinarian opponent is more promising. Here, the great Louis Duchesne, who a century ago pointed to the likelihood that the Praedestinatus was connected in some way with the last desperate initiative by Julian of Eclanum to seek reconciliation with Rome and restoration to his see in 439, offers a way forward.Footnote ³⁸ Prosper's Chronicle entry for that year includes a bitter entry about Julian, lambasting him for his bragging and deceit as part of this attempt: ‘iactantissimus Pelagiani erroris adsertor’ and ‘multimoda arte fallendi’ are the phrases used of him.Footnote ³⁹ Prosper broke with his usual calm tone in the remainder of his Chronicle to launch this vituperative attack on Julian. There is real personal animus here which mirrors that found in the references to Prosper in the Praedestinatus and Commentarii. Footnote ⁴⁰ If a personal clash in 431 is ruled out, the raging attack on Julian's attempt at restoration in Prosper's chronicle entry for 439 seems to reflect the general, if not all the specific circumstances described in book iii of the Praedestinatus.

Where, though, is the evidence of a situation where others were present along with Prosper's chief adversary in a personal confrontation as described in Praedestinatus iii.8? While there is no definite proof that many of the Italian exiles of 419 returned en masse along with Julian, it is a fair deduction. It is known that Leo i spent the early years of his pontificate during the 440s conducting mopping-up operations against them throughout Italy.Footnote ⁴¹ Consequently, it is likely that the attempted restoration of their leader did provide the occasion for their return in strength. Nothing is heard about them previously during most of the pontificate of Xystus iii after their expulsion from Constantinople in 430. The pursuit of disguised Pelagians, as Leo describes them, shortly afterwards, is clearly attested by the De promissionibus attributed to Quodvultdeus,Footnote ⁴² by PhotiusFootnote ⁴³ and in Leo's own correspondence (epp. i, ii).Footnote ⁴⁴ The demand for a full consideration of the doctrines of Julian and his associates by a properly convened synod of bishops had been a common objective since 418–19. It is entirely plausible that a conference was held in 439 to debate their views before a council of the Roman Church, especially under a pope, Xystus, who had once been corrected after showing sympathy for Pelagius.Footnote ⁴⁵ Certainly, after 439, with the former bishop of Eclanum rebuffed again by Rome, there could have been no such open debate with their opponents in the West as described in the Praedestinatus. If Prosper engaged in debate with a single adversary in this context, but an adversary surrounded by a group of supporters, in an atmosphere of bitter recrimination, then we once again have to consider the intriguing possibility that Arnobius and Julian were one.

A dating of the Commentarii in Psalmos and the Praedestinatus to a period beginning in 439 fits in with other evidence surrounding the controversy between Prosper and the so-called Arnobius to which these texts bear witness. Gumerlock has established that the two works were part of a series of literary productions prompted by the debate over predestination. Prosper replied to the In Psalmos of Arnobius with his own Expositio in Psalmos. He commented only on Psalms c–cl as that was the section of the Psalter where the latter had expressed his objectionable theology of grace most clearly in expounding Psalms cviii, cxvii, cxxvi and cxlvi.Footnote ⁴⁶ But one work which seems to form an integral part of the polemical contest between the two opponents has been neglected. This is the text of the Hypomnesticon, critically edited by J. E. Chisholm and attributed by him after exhaustive study to Prosper.Footnote ⁴⁷ Other scholars have proved reluctant to accept this attribution, although without cogent reasons.Footnote ⁴⁸ On more detailed examination, it becomes clear that this text is closely related to the three works cited above on the Psalms and the ‘predestined one’ or Praedestinatus. The form of address used is direct and polemical, ‘audi’ and ‘ausculte’.Footnote ⁴⁹ Both authors speak in the first person and slip into the second person, and indeed, the second person singular in addressing a particular opponent.Footnote ⁵⁰ Hypomnesticon demonstrates a clash with an undefined adversary over the nature of grace and the issue of whether predestination is orthodox or heterodox but also encompasses an attack on Julian's belief in the goodness of concupiscentia within marriage.

The Hypomnesticon was produced in two stages, beginning with responsiones i–v, to which responsio vi was hastily added later. This is abundantly clear from the failure to update the preface giving the number of separate sections within the work, which speaks of only five propositions which are considered. Responsio iv is an attack on Julian of Eclanum's teaching on concupiscentia, but responsio vi, which is transmitted independently in some manuscripts, is a vigorous defence of predestination.Footnote ⁵¹ It looks, therefore, as though the work was originally produced as a riposte to Julian and his followers, after tracing their errors back to Pelagius and Celestius, but that the last section represents an attempt to rebut the specific attacks of the so-called Arnobius in the Praedestinatus. In particular, the author of Hypomnesticon reiterates what the opponent of Arnobius is reported to have said in book iii of Praedestinatus. He bluntly states that not all men are to be saved and that the ‘omnes’ of 1 Timothy ii.4 are not all men as such, but only the body of the elect to whom God wishes to grant salvation.Footnote ⁵² If we accept that the clash between Arnobius and his opponents referred to in the Commentarii and the Praedestinatus probably occurred in 439, and lay in the recent past, then the Hypomnesticon and Expositio super Psalmos seem to be part of Prosper's response in the period shortly after. This is important, because it is likely that such a prolonged exchange takes us into the pontificate of Leo i, whose election occurred in August 440. Under Leo, Photius states that Prosper wrote libelli (pamphlets) against the Pelagians.Footnote ⁵³ The Hypomnesticon seems to fit this description exactly: it attacks teachings in works attributed to Arnobius and other doctrines of Julian which were deemed by the author to be Pelagian. The vehement denial by Arnobius of any unorthodox beliefs and his condemnation of Pelagius was a response to Prosper's attacks as encapsulated in these two polemical works by his Aquitanian opponent.Footnote ⁵⁴ It is apparent that the Hypomnesticon forms part of the series of works provoked by a direct encounter with the author of the Praedestinatus.

Whatever the actual circumstances of the clash between Prosper and the figure of Arnobius, certain features are clear. Our mysterious polemicist appears as a spokesman and leading figure among an anti-predestinarian group seeking to drive a wedge between the supposedly ‘true’ teaching of Augustine and that of the extreme predestinarians who had allegedly corrupted it. Indeed, he goes so far in the Praedestinatus as to take and rework Augustine's De haeresibus and to add the praedestinati as the last heretics in the list. That itself seems to point to an attempt to exploit the very guarded endorsement of Augustine by Celestine in 431. After the pope's judgement, the great African theologian could no longer be challenged head-on but his reception could be manipulated by isolating and attacking the predestinarian element in his work.Footnote ⁵⁵

The substantial obstacle to placing Arnobius in the circle of Julian is that other scholars have seen too great a divergence between the beliefs articulated by these supposedly separate figures. In particular, Maurice Abel has pointed out that while Julian of Eclanum repeatedly rejected the doctrine of original sin in any form, Arnobius in contrast seems to accept it through the condemnation of Celestius, the chief opponent of the doctrine, in the Praedestinatus. Footnote ⁵⁶ Although Abel traced an extensive overlap between the teachings and style of these two figures, he concluded that Arnobius was a ‘semi-Pelagian’ (the dubious and now discarded categorisation previously applied to Cassian's followers) who lived in Rome at the same time and who was influenced by Julian's teachings. But Abel's one major objection to Arnobius' being a returning Italian exile dissolves on closer examination. The key lies in another work attributed to Prosper of Aquitaine, the Epistola ad Demetriadem. This was written partly to deter the aristocratic Roman virgin Demetrias from showing sympathy for the returning Italian anti-predestinarians, when some were speaking up for them in Rome.Footnote ⁵⁷ The author seems to refer to these exiles in his statement when he writes that:

This stance is in line with the deceit with which Prosper charges Julian and his followers in 439. It is also something that Leo i warned his fellow Italian bishops against when considering the reconciliation of these returning exiles.Footnote ⁵⁹ Abel and others who have followed him have been too trusting in accepting Arnobius at face value. In reality, his two anti-predestinarian works are in essence an elaborate attempt at deception, to disguise his opposition to Augustine's views on grace and free will in a last-ditch attempt to avoid the complete triumph of Augustinian theology and the renewed proscription of the irreconcilable anti-predestinarian Italian churchmen in the wake of the failure of Julian's appeal to Xystus. If the strictures of Prosper and Leo, who had first-hand experience of dealing with Julian and the returning Italian exiles, are accepted, everything falls into place and Abel's objection dissolves. Arnobius, whoever he might have been, was indulging in dissimulation in common with the rest of Julian's followers. After the condemnation of Celestius’ views on original sin by Rome and also at the Council of Ephesus in 431, it was not possible openly to oppose the doctrinal position that Adam's sin was transmitted to all men directly and it is hard to see how the exiled Julian and his party could have obtained a hearing at Rome in 439 without disguising their true opinions on this issue.

When other teachings of Arnobius and Julian of Eclanum are compared they are overwhelmingly close. There is the same emphasis on the essential goodness of concupiscentia, that natural desire which, it is argued, does not stem from the devil, and the benign nature of the attraction between the sexes and procreation; the goodness of marriage which the Church blesses; the goodness of man as the creation of God and the belief that any other position is Manichaean; the freedom of the will which has survived the Fall of Adam; and the consequent belief that the possibilitas mali is to be welcomed because without it there can be no positive virtue in exercising freedom and choosing good.Footnote ⁶⁰

Another striking similarity between the works of these two supposedly distinct figures is their emphasis on reason. Julian stressed the primacy of reason in his scriptural exegesis and polemical works, exalting it above authority. In his Commentary on Job he employs the word ratio no less than sixty-three times.Footnote ⁶¹ Arnobius takes the same attitude, condemning his predestinarian opponent, not by resorting to authority, but by employing ‘true reasoning’.Footnote ⁶²

Moreover, the style of Arnobius, and his arguments, are very reminiscent of Julian. There are eight clear echoes of the latter's literary oeuvre (as cited by Augustine) in the Praedestinatus which are noted in Gori's edition.Footnote ⁶³ Of these, seven parallels are particularly notable (see table 1). The final image, that of the shaven hair, is used by Julian (cited by Augustine, Contra duas epistolas Pelagianorum 1.13.26; 1.22.40) and Arnobius (Praedestinatus ii.7.35–41) alone. Echoes of style and ideas cannot themselves be conclusive, but they do show a close connection between the two authors. A number of other characteristics of the former bishop of Eclanum appear in the two works of Arnobius identified by Bouwman, Baxter and Morin.Footnote ⁶⁴ Both authors constantly use words with the suffix -tor, -tas and -tio.Footnote ⁶⁵ There is the same fondness for verbs ending in -escere.Footnote ⁶⁶ Baxter identified that the author of the Praedestinatus used the word ‘applicare’ in a special sense of ‘to impute to’ or ‘attribute to’ which is characteristic of Julian.Footnote ⁶⁷ Notable too, is the privileging of St John Chrysostom, the eastern Father revered by Julian and his followers.Footnote ⁶⁸ Furthermore, if the Hypomnesticon attributed to Prosper of Aquitaine is taken into account the connection becomes even closer. The author of the work makes a charge against his opponent which is highly distinctive. He accuses his antagonist of loquacity in the context of an attack in responsio iv.7.295 on the belief propagated by Julian of Eclanum that moderate concupiscence is essentially good: ‘Pergite adhuc per campos loquacitatis vestrae.’Footnote ⁶⁹ The charge of loquacity, or what Henry Mayr-Harting has memorably referred to as verbal diarrhoea, is a highly unusual and distinctive one to bring against a theological opponent. It is regularly used of one individual and one only in the course of fifth-century controversies, and originates with Augustine in speaking of Julian.Footnote ⁷⁰ Clearly, he is attacking not just Julian's beliefs but Julian himself. As the author of Hypomnesticon frequently uses the second person singular to address his opponent in responsiones iv–vi, it looks very much as though he is addressing the same individual throughout. If so, it points strongly to Julian being the target of his invective as otherwise it would have been appropriate to differentiate the subject of responsio vi (the so-called Arnobius who had savaged Prosper in the Praedestinatus) from Julian in responsio iv.

Table 1. Similarities between Arnobius and Julian (as transmitted via Augustine)

* The alternative reading ‘radere’ seems preferable here and later in the passage as given in the notes to this edition: CSEL lx.445.

The pieces of the jigsaw now come together. Morin made much of the ‘African’ traits of Arnobius, including a claim that he used versions of the African Bible and that there are echoes of the African Church's liturgy in his writings such as the use of the phrase sursum cor rather than the Italian usage sursum corda.Footnote ⁷¹ Even if this is correct, the influences can be accounted for in other ways. In particular, Morin ignores the fact that Julian of Eclanum had himself spent time in Africa, at Carthage in about 409–10.Footnote ⁷² He also passes over the knowledge of eastern liturgy which Arnobius displays,Footnote ⁷³ and his familiarity with the Greek text of the Bible.Footnote ⁷⁴ Furthermore, Arnobius is clearly steeped in the passiones of martyrs venerated in Rome and suburbicarian Italy.Footnote ⁷⁵ The intimate knowledge of Greek church practices and the Italian references fit well with the circumstances of Julian's party of exiles who spent long years in the East after their expulsion from Italy in 419. There are numerous other stylistic fingerprints of the deposed bishop of Eclanum in the works of Arnobius against predestination. The jeering sarcastic, tone of the Praedestinatus towards the ‘predestined one’ closely parallels the irreverent stance which Julian adopted towards Augustine over grace, concupiscence and original sin.Footnote ⁷⁶ It would be entirely in keeping for Julian or one of his associates to propagate his opposition to the bishop of Hippo's more contentious views under the guise of a name suggestive of an older African Christianity in the Commentarii.Footnote ⁷⁷

It may not yet be time to remove Arnobius the Younger from the reference books, but his existence is certainly highly questionable. It is much more plausible and economical to ascribe the two works most clearly emanating from his pen to Julian or his exiled associates. Of those followers, allowing for the fact that some such as Turbantius had fallen away by the 430s,Footnote ⁷⁸ it is difficult to see who might have had the knowledge and range which these works display. Bishop Florus could in theory be a possible candidate. He was one to whom Julian addressed works before 430. But there is no evidence that he was ever a polemicist, although he remained active in the vicinity of Naples during the 440s.Footnote ⁷⁹

On the current balance of probabilities, Prosper's hated opponent Julian is the prime candidate for authorship of these works, disguising his views where necessary in order to carry on the fight against Augustine and to prove himself a true Catholic in the face of African innovation. It is hard to think of any other figure with the chutzpah to attack Augustine's teaching on predestination by claiming that his works had been contaminated by heretics. Certainly, there is evidence that Julian remained active in Italy during the 440s, and since the terminus ad quem for his death is March 455,Footnote ⁸⁰ the disguised or dissimulating works, Commentarii in Psalmos and Praedestinatus, appearing to stem from the pen of an otherwise unknown Arnobius, would neatly help to fill the void in terms of literary productions from this inveterate polemicist and biblical commentator in the years after 439.Footnote ⁸¹ It is precisely the period when Prosper and Leo were involved in countering the returning exiles led by Julian and when the former bishop of Eclanum is most likely to have wished to attack Prosper as the leading proponent of Augustine's extreme predestinarian teachings.