Ambrosiaster or Pseudo-Ambrosius a name generally employed to denote the unknown author of the Commentaria in xiii Epistolas beati Pauli formerly ascribed to St. Ambrose and usually printed along with his works. The commentary itself contains no definite indication of its authorship. An incidental remark however on 1Ti_3:15 "Ecclesia . . . cujus hodie rector est Damasus," shows that it was written during the pontificate of Damasus (366â€“384). It has been suggested that this clause may be an interpolation; but such an interpolation seems difficult to account for. Other marks negative and positive point to the same period. The text used is not the Vulgate but a prior form of the Latin version. The ecclesiastical authors to whom he refersâ€”Tertullian Cyprian Victorinusâ€”belong to an earlier date. Among the heresies which he mentions he applies himself more especially to those of the 4th cent.â€”e.g. those of Arias Novatian Photinusâ€”while the absence of allusion to later forms of error points the same way. He speaks of the Marcionites as on the verge of extinction ("quamvis pene defecerint," in Ep. ad Timoth. I. iv. 1). The date thus indicated would be the latter half of the 4th cent.; although in that case it is certainly somewhat surprising that Jerome in his treatise de Scriptoribus Ecclesiasticis should not mention any other Latin commentator on the Pauline Epistles than Victorinus.
It was the generally received opinion in the Middle Ages that our author was Ambrose bp. of Milan; but this belief which Erasmus was among the first to question is now universally admitted to rest on no sufficient grounds though opinions differ much as to the probable author. From certain expressions which appear favourable to Pelagianism the work has been assigned by some to Julian of Aeclanum; but as Richard Simon has naÃ¯vely remarked "if the writer does not always appear orthodox to those who profess to follow the doctrine of St. Augustine it must be taken into account that he wrote before that Father had published his opinions." The expressions in question were probably employed without reference to the Pelagian controversy and previous to its emergence and are moreover accompanied by others entirely incompatible with a Pelagian authorship (e.g. the statement in Ep. ad Rom_5:12 "Manifestum est in Adam omnes peccasse quasi in massÃ¢").
The only positive statement as to the authorship is contained in the following passage of Augustine, Contra duas Epistolas Pelagianorum, lib. iv. c. 7: "Nam et sic sanctus Hilarius intellexit quod scriptum est, in quo omnes peccaverunt: ait enim, 'In quo, id est in Adam omnes peccaverunt.' Deinde addidit: 'Manifestum est in Adam omnes peccasse quasi in massÃ¢; ipse enim per peccatum corruptus, quos genuit omnes nati sunt sub peccato.' Haec scribens Hilarius sine ambiguitate commonuit, quomodo intelligendum esset, in quo omnes peccaverunt." As the words cited are found in this commentary, it may be reasonably assumed that the statement applies to it, and that Augustine reckoned Hilarius its author. Of the persons of that name, Augustine elsewhere mentions only Hilarius the Sardinian, deacon of the Roman church, sent by pope Liberius in 354 to the emperor Constantius after the synod of Arles. By many modern scholars Hilary the deacon has been accepted as the author of the work. But Petavius and others have objected that Augustine was not likely to apply the epithet sanctus to one whom he must have known to be guilty of schism. There can be little doubt that, whoever was the author, the work no longer retains its original form. The well-meaning zeal of copyists appears to have freely inserted comments from various sources, such as Augustine, Chrysostom, Jerome, the commentary which is printed at the end of the works of Jerome and is usually ascribed to Pelagius. These circumstances sufficiently account for the various forms of the text in MSS., and for the discrepancies and inequalities of treatment in several parts.
There is, moreover, a marked affinity between this commentary and certain portions of the Quaestiones Veteris et Novi Testamenti usually printed with the works of St. Augustine. The similarity of ideas and, in various cases, identity of language can only be explained by supposing either that they have had a common author, or that the writer of the one work has borrowed largely from the other. The note of time in the Quaestiones â€”300 years after the destruction of Jerusalemâ€”and some references to contemporary events suit the period of Damasus, and have induced many to ascribe this work also to Hilary the deacon. But the authorship of both remains uncertain, and probably the Quaestiones was composed subsequently to the commentary.
The commentary on the Pauline Epistles, notwithstanding its inequalities of treatment, is of great value, and is well characterized by Sixtus Senensis as "brief in words, but weighty in matter"; and, although the writer is frequently controversial, he speedily returns to the proper work of exegesis. In consequence of his use of the old Latin version and frequent reference to various readings, his work affords important materials for textual criticism.
The commentary on the Epistle to the Hebrews, which accompanies the others in some editions, but is omitted by the Benedictine editors, is a compilation from various Patristic sources, principally from Chrysostom. Cf. H. B. Swete, Theod. Mops. Comm. (1880), vol. i. p. lxxviii., vol. ii. p. 351.
The commentary was issued separately at Cologne in 1530 and 1532. Cf. A Study of Ambrosiaster by A. Souter (Camb. Univ. Press); Text and Studies , vol. vii. No. 4.