Saint Prosper of Aquitaine

Theologian and Defender of Grace
(c. 390–455)

Saint Prosper of Aquitaine was born around 390 in the province of Aquitaine in Roman Gaul and received an excellent classical education that is evident in all his writings. He was not a cleric but a layman of great learning and piety who became one of the most zealous defenders of the theology of grace developed by Saint Augustine of Hippo. Prosper lived through the twilight years of the Western Roman Empire and witnessed both the theological controversies of his time and the barbarian invasions that were transforming the face of the world.

When the Semi-Pelagian controversy broke out in the monasteries of southern Gaul, particularly at Marseilles under the influence of John Cassian, Prosper became the most energetic lay defender of Augustinian orthodoxy. He engaged in vigorous written debate with the monks of Provence who wished to soften Augustine's doctrine on grace and predestination, and he wrote personally to Saint Augustine himself to inform him of the controversy and seek his guidance. Augustine responded with two works, On the Predestination of the Saints and On the Gift of Perseverance, which were largely composed in response to Prosper's letters.

After Augustine's death in 430, Prosper continued to defend his teaching with great energy. He made a journey to Rome to consult Pope Celestine I, who issued a letter strongly approving the Augustinian position. Prosper then composed a work drawing out the doctrinal implications of the papal statement. He also composed a lengthy poem in Latin hexameters summarising Augustine's teaching on grace, demonstrating his considerable literary gifts in the service of theological truth.

In his later years Prosper served in Rome as a secretary or close collaborator of Pope Leo the Great, and it is probable that he had some part in the composition of some of Leo's famous letters and sermons. He also composed a chronicle of world history, which is an important source for the events of his time, and a collection of doctrinal sentences drawn from the works of Augustine that became a standard reference work in the medieval theological tradition.

He died around 455, having spent his life in the service of Catholic truth and in particular in the defence of the absolute priority of divine grace in the work of salvation. He is venerated as a saint in some traditions and his feast is kept on June 25th. His writings are among the most important sources for understanding the theological controversies of the fifth century.