c.339-397. Bishop of Milan. Born at Trier in Gaul into the Christian family of Aurelius Ambrosius, the praetorian prefect of Gaul, he trained in law, followed his father into an administrative career, and about 370 was appointed governor of the province of Aemilia-Liguria, the leading town of which was Milan. When Auxentius, bishop of Milan, died in 374, Ambrose (an unbaptized catechumen) was baptized, ordained, and consecrated bishop. His first act as bishop was to distribute his great wealth among the poor. He was outstanding as preacher and teacher; his De Fide, De Spiritu Sancto, and De Mysteriis are testimony to his diligence in teaching the faith and refuting heresy. Among the many influenced by him was Augustine,* whose fame and ability were one day to eclipse even his own. Ambrose was also a fearless church leader. Events brought him into contact with the rulers of the West. When Theodosius had put down a seditious movement in Thessalonica with exceptional severity by killing thousands of people, Ambrose wrote to him refusing the sacrament of until he had openly made penance. Ambrose's attitude was to affect profoundly relationships between church and state for generations to come. “The emperor,” he declared, “was within the church and not over it.” Ambrose was influential also in encouraging monasticism in Italy and molding psalmody and hymnody in the direction of congregational participation. His main work, De Officiis Ministrorum, was a book on Christian ethics for the clergy.
See F. Homes Dudden, The Life and Times of St. Ambrose (2 vols., 1935); and W.G. King, The Emperor Theodosius and the Establishment of Christianity (1961).