Hilary , a pope of Rome, successor of St. Leo I.", born in Sardinia, died in 468. From the beginning of his priesthood he had been noted for his zeal for the faith and his hostility to heresy. At the "robber council" of Ephe-sus, in 449, he appeared as the representative of Leo, sustaining the doctrine of the church against the theory of Eutyches. He was chosen to the Roman see in 461. He improved the discipline of the church, confirmed the anathema against Nestorius and Eutyches, prohibited the long established practice of bishops nominating their successors, forbade men who had been twice married or who had married widows to receive holy orders, held at Rome in 465 a council for reforms, and solemnly ratified the former oecumenical councils.
Hilary , (Hilarius), a saint of the church, born in Poitiers about the year 300, died there in 367 or early in 368. His parents, who were pagans of patrician rank and very wealthy, gave him a careful education. He was of ripe age, distinguished for learning and eloquence, when, with his wife and daughter, he embraced the Christian faith. About 353 he was chosen bishop of his native city, and set himself zealously to combat the Arian heresy, which was then the religion of the emperor Constantius II., and predominant in Italy, Spain, and Africa, and which the protection of the emperor and his officers and their persecution of the orthodox were making popular among the people and clergy of Gaul. In 355 Hilary wrote to the emperor, remonstrating with him on this persecuting spirit. In 356 he was induced to present himself to the council of Be-ziers, almost entirely composed of Arian bishops, when he attacked Saturninus of Aries, the apostle of Arianism in Gaul, but was condemned by the majority, denounced to the emperor as a disturber of the peace of the church, and banished to Phrygia, together with his friend Rodanius, bishop of Toulouse. From his exile he wrote frequently to his flock and his brother bishops in Gaul to stir up their faith, fortitude, and zeal.
He composed at the same time his work on "Synods," which was written in a conciliatory spirit, and his 12 books on "The Trinity," which became the standard of orthodoxy in the western churches. In 359, at the instance of the emperor and the Asiatic bishops, he assisted at the council of Seleucia in Isauria, and triumphantly defended the divinity of Christ. From thence he went to Constantinople, where he boldly arraigned the emperor and his Arian counsellors, who deemed it advisable to send him back to Gaul. Before leaving the capital he wrote his vehement "Invective against Constantius." He assembled several councils after his return to Poitiers, and obtained the deposition of Saturninus, and a formal retractation from nearly all the bishops who had subscribed to the creed of Ariminum. He then passed over into Italy to oppose as well the untimely severity of the orthodox Lucifer as the proselytizing and persecuting zeal of Auxentius, the favorite of the new emperor Valentinian; but he was forced by an imperial order to return to his diocese, where he soon after died.
St. Jerome calls Hilary " the Rhone of Latin eloquence " (Latinoe eloquentioe Rhodanus). The best editions of his works are that published by the Benedictine Constant (fob, Paris, 1G93; republished by Maffei with several additions, Verona, 1730), and that of Oberthuer (4 vols. 8vo, Wurzburg, 1781-8). - See Reinkens's monograph, Hilarius von Poitiers (Schaffhausen, 1864; Breslau, 1865).