St. Hilary was a native of Poitiers, in Aquitaine. Born and educated a pagan, it was not till near middle age that he embraced Christianity, moved thereto mainly by the idea of God presented to him in the Holy Scriptures. He soon converted his wife and daughter.
He entered Holy Orders, and in 353 was chosen bishop of his native city. Arianism, under the protection of the Emperor Constantius, was just then in the height of its power, and St. Hilary found himself called upon to support the orthodox cause in several Gallic councils, in which Arian bishops formed an overwhelming majority. He was in consequence accused to the emperor, who banished him to Phrygia. He spent his three years and more of exile in composing his great works on the Trinity.
In 359 he attended the Council of Seleucia, in which Arians, semi-Arians, and Catholics contended for the mastery. With the deputies of the council he proceeded to Constantinople, and there so dismayed the heads of the Arian party, that they prevailed upon the emperor to let him return to Gaul.
He traversed Gaul, Italy, and Illyria, wherever he came discomfiting the heretics, and procuring the triumph of orthodoxy. After seven or eight years of missionary travel he returned to Poitiers, where he died in peace in 368.
Illustration and text from Pictorial Lives of the Saints With Reflections for Every Day in the Year (New York: Benziger Bros., 1922).