June 25 - Prosper was born in Aquitaine around 390 and seems to have studied in Marseille, where he is now at the end of the 420s, at the very moment when Jean Cassien and his monks give birth, in reaction to the last Augustinian writings on grace, to what will be called at the end of the 16th century "Semipelagianism".
In 429 he corresponds with St. Augustine on this subject. In 431 he came to Rome to question Pope Celestine I about Augustine's teachings. In 440, during the first year of his pontificate, Leo I called him to him as his secretary. The date of his death is not known, but his chronicle runs as far back as 455, and Marcellin's chronicler mentions it in 463, which seems to indicate that his death occurred shortly after that date.
Prosper was a layman, but he threw himself ardently into the religious controversies of his time, in defence and propagation of Augustine's thought. In his "De omnium gentium vocatione" ("The Call of All Nations"), in which the question of the call of the Gentiles is examined in the light of Augustine's doctrine of grace, Prosper appears as the first of the medieval Augustinians.
His main work is "De gratia Dei et libero arbitrio" (432), written against the "Collatio" of John Cassian. He also urged Pope Celestine to publish an open letter to the bishops of Gaul, "Epistola ad episcopos Gallorum" against certain members of the Church of Gaul. He had already opened a correspondence with St. Augustine, with his friend Hilary (who is not Hilary of Arles), and although he was unable to meet him physically, his enthusiasm for the great theologian led him to make an abridged version of his commentary on the Psalms, as well as a collection of sentences taken from his works, probably the first dogmatic compilation of this kind, in which Pierre Lombard's "Liber Sententiarum" is the best known example. He also versified in 106 epigrams some of Augustine's so-called theological.
Much more important historically is the "Epitoma Chronicon" (covering the period from 379 to 455) which Prosper first composed in 433 and completed several times until 455. In the absence of other sources, it is very valuable for the period from 425 to 455, drawn from the personal experience of Saint Prosper. Compared to his followers, Prosper gives a detailed account of political events. It covers the invasions of Attila of Gaul (451) and Italy (452). There have been five different editions, the last one dating from 455, just after the death of Valentinian III.
