ARNOBIUS THE YOUNGER. - Christian writer, probably a monk, who lived in Rome around the mid-5th century; perhaps originally from Gaul. The scant and uncertain data we have about his life is matched by an equal uncertainty regarding his literary work, which recent scholarship, especially through the efforts of the Benedictine G. Morin, has sought to reconstruct. In addition to his Commentaries on the Psalms (PL 53, 486 and 552), he is probably the author of some minor Expositinculae on the Gospel (ed. by G. Morin in Anecdota Maredsolana, III, 3, Maredsous 1903, pp. 129-51) and of the Conflictus Arnobii catholici cum Serapione Aegyptio (PL 73, 569-80), a superficial polemic against the Monophysites. Morin also attributes to him a Libellus ad Gregoriam (ed. by G. Morin, in Etudes, textes, découvertes, I, Maredsous 1913, pp. 383-439), a pamphlet once attributed to John Chrysostom, in which advice is given to the Roman lady Gregoria on how to find happiness in married life, and the three-book treatise Praedestinatus (PL 73, 587-672). The importance of these works lies in the stance they take, especially in the Commentaries and the Praedestinatus, regarding the much-debated question of grace and predestination, in more or less open contrast to the extreme views held by St. Augustine in his polemic against the Pelagians, particularly Julian of Eclanum.
From an examination of the Praedestinatus it emerges that A. is rather a semi-Pelagian than a Pelagian in the manner of Julian of Eclanum, and that he presents, as the creed of a supposed predestinarian heresy, a composition of his own designed to discredit Augustinian doctrine. The spiritual outlook of the author of the Commentaries on the Psalms is not dissimilar, though closer to orthodoxy, in that he acknowledges and deplores the harm done to humanity by original sin; a clear link between the two works is the high esteem in which they hold the ascetic ideal and the life of continence. All this points to the conclusion that the same author is responsible for both. The problem remains of how the same author could, in the Conflictus, subscribe to Augustinian theses. Morin suggests that the author freed himself from Pelagian ideas “as the ever-clearer action of Roman authority... made him see the opportunity [to do so].”