Ausonius, Decimus Magnus , a native of Bordeaux, was the son of Julius Ausonius, a physician of Cossium (Bazas ), in Aquitania (Aus. Idyll. ii. 2). His poems, which are singularly communicative as to his private history, display him to us in riper years both as student and courtier, professor and prefect, poet and consul. At the age of 30 he was promoted to the chair of rhetoric in his native city, and not long after was invited to court by the then Christian emperor Valentinian I., who appointed him tutor to his son Gratian ( Praef. ad Syagr. 15–26). Ausonius was held in high regard by the emperor and his sons and accompanied the former in his expedition, against the Alemanni. It was no doubt during the residence of the court at Trèves at this time that he composed his Mosella . From Valentinian he obtained the title of Comes and the office of Quaestor, and on the accession of Gratian became successively Prefect of Latium, Libya, and Gaul, and finally, A.D. 379, was raised to the consulship (Praef. ad Syagr. 35, etc.; Epigr. ii. iii., de fast. ). After the death of Gratian, A.D. 383, although he seems to have enjoyed the favour of Theodosius (Praef. ad Theodos. ), it is probable that he returned to the neighbourhood of his native city and spent the remainder of his life in studious retirement (Ep. xxiv.). His correspondence with Paulinus of Nola evidently belongs to these later years. The date of his death is unknown, but he was certainly alive in A.D. 388, as he rejoices in the victory of Theodosius over the murderer of Gratian at Aquileia ( Clar. Urb. vii.).

The question of the poet's religion has always been a matter of dispute. Voss, Cave, Heindrich, Muratori, etc., maintain that he was a pagan, while Jos. Scaliger, Fabricius, Funccius, and later M. Ampère, uphold the contrary view. Without assenting to the extreme opinion of Trithemius, who even makes him out to have held the see of Bordeaux, we may safely pronounce in favour of his Christianity. The negative view rests purely upon assumptions, such as that a Christian would not have been guilty of the grossness with which some of his poems are stained, nor have been on such intimate terms with prominent heathens (Symmach. Epp. ad Auson. passim), nor have alluded so constantly to pagan rites and mythology without some expression of disbelief. On the other hand, he was not only appointed tutor to the Christian son of a Christian emperor, whom he seems at any rate to have instructed in the Christian doctrine of prayer ( Grat. Act. 43); but certain of his poems testify distinctly to his Christianity in language that is only to be set aside by assuming the poems themselves to be spurious. Such are (1) the first of his idylls, entitled Versus Paschales , and commencing Sancta salutiferi redeunt solemnia Christi, the genuineness of which is proved by a short prose address to the reader connecting it with the next idyll, the Epicedion , inscribed to his father. (2) The Ephemeris , an account of the author's mode of spending his day, which contains not merely an allusion to the chapel in which his morning devotions were performed (I. 7), but a distinct confession of faith, in the form of a prayer to the first two Persons of the Trinity. (3) The letters of the poet to his friend and former pupil St. Paulinus of Nola, when the latter had forsaken the service of the pagan Muses for the life of a Christian recluse. This correspondence, so far from being evidence that he was a heathen (see Cave, etc.), displays him to us rather as a Christian by conviction, still clinging to the pagan associations of his youth, and incapable of understanding a truth which had revealed itself to his friend, that Christianity was not merely a creed but a life. The letters are a beautiful instance of wounded but not embittered affection on the one side, and of an attachment almost filial tempered by firm religious principle on the other. Paulinus nowhere chides Ausonius for his paganism; on the contrary, he assumes his Christianity (Paulin. Ep. ii. 18, 19), and this is still further confirmed by a casual passage in one of the poet's letters to Paulinus, in which he speaks of the necessity of returning to Bordeaux in order to keep Easter ( Ep. viii. 9). Ausonius was not a Christian in the same sense as Paulinus; he was one who hovered on the borderland which separated the new from the old religion: not ashamed, it is true, to pen obscenities beneath the eye and at the challenge of his patron, yet in the quiet of his oratory feeling after the God of the Christians; convinced apparently of the dogma of the Trinity, yet so little penetrated by its awful mystery as to give it a haphazard place in a string of frivolous triplets composed at the dinner-table ( Gryph. Tern. 87): keenly alive to natural beauty, and susceptible of the tenderest affection, he yet fell short of appreciating in his disciple the more perfect beauty of holiness, and the entire abnegation of self for the love of a divine master. Probably his later Christianity would have disowned his own youthful productions.

The works of Ausonius comprise: Epigrammaton Liber , a collection of 150 epigrams on all manner of subjects, political, moral, satirical, amatory; many of which for terseness and power of sarcasm are only surpassed by those of Martial. Ephemeris (see above). Parentalia , a series of tributes to the memory of those of his family and kindred who had died before him, many of which are full of pathos. The Mosella is a poem in praise of his favourite river. The Epistolae are, on the whole, the most interesting, because the most heartfelt, of the works of Ausonius; they number 25, addressed to various friends. Those to St. Paulinus of Nola prove that the poet was capable of earnestness when his heart was stirred.

The works of Ausonius are published in Migne's Patr. Lat. vol. xix. There is a complete ed. by R. Peiper (Leipz. 1886); H. de la V. de Mirmont, Mosella , with trans. (Bordeaux, 1889); also de Mosella (Paris, 1892); Dill, Roman Society (Lond. 1898).