Prosper was a native of Aquitaine, and seems to have been educated at Marseilles. In 431 he appeared in Rome to interview Pope Celestine I regarding the teachings of St Augustine and there is no further trace of him until 440, the first year of the pontificate of Pope Leo I, who had been in Gaul and may have met Prosper. In any case Prosper was soon in Rome, attached to the pope in some secretarial or notarial capacity. Gennadius (De script. eccl. 85) mentions a rumour that Prosper dictated the famous letters of Leo I against Eutyches. The date of his death is not known, but his chronicle goes as far as 455, and the fact that the chronicler Marcellinus mentions him under the year 463 seems to indicate that his death was shortly after that date.
Prosper was a layman, but he threw himself with ardour into the religious controversies of his day, defending Augustine and propagating orthodoxy. The Pelagians were attacked in a glowing polemical poem of about 1000 lines, Adversus ingratos, written about 430. The theme, dogma quod ... pestifero vomuit coiuber sermone Britannus, is relieved by a treatment not lacking in liveliness and in classical measures. After Augustine's death he wrote three series of Augustinian defences, especially against Vincent of Lerins (Pro Augustino responsiones).
His chief work was against Cassian's Collatio, his De gratia del ut libero arbitrio (432). He also induced Pope Celestine to publish an Epistola ad episcopos Gallorum against Cassian. He had earlier opened a correspondence with Augustine, along with his friends Tyro and Hilary of Arles, and although he did not meet him personally, his enthusiasm for the great theologian led him to make an abridgment of his commentary on the Psalms, as well as a collection of sentences from his works--probably the first dogmatic compilation of that class in which Peter Lombard's Liber sententiarum is the best-known example. He also put into elegiac metre, in 106 epigrams, some of Augustine's theological dicta.
Far more important historically than these is Prosper's Epitoma chronicon. It is a careless compilation from Saint Jerome in the earlier part, and from other writers in the later, but the lack of other sources makes it very valuable for the period from 425 to 455, which is drawn from Prosper's personal experience. There were five different editions, the last of them dating from 455, just after the death of Valentinian III. For a long time the Chronicon imperiale was also attributed to Prosper Tiro, but without the slightest justification. It is entirely independent of the real Prosper, and in parts even shows Pelagian tendencies and sympathies.
The Chronicon was edited by Mommsen in the Chronica minora of the Monumenta Germaniae historica (1892). The complete works are in Migne's Patroiogia latina. Tome 51. See L. Valentine, St. Prosper d'Aquitaine (Paris, 1900), where a complete list of previous writings on Prosper is to be found; also A Potthast, Bibliotheca historica (1896).
This entry was originally from the 1911 Encyclopedia Britannica.