Saint Irenaeus was born in the year 120; he was Greek and probably a native of Asia Minor. His parents, who were Christians, placed him while still young under the care of the great Saint Polycarp, Bishop of Smyrna.

      It was in this holy school that he learned the sacred science which later made him a great ornament of the Church and the terror of her enemies. Saint Polycarp cultivated his rising genius and formed his mind to piety by his precepts and example, and the zealous young scholar was careful to reap all advantages offered him by the solicitude of such a master. Such was his veneration for his tutor's sanctity that he observed all the acts and virtues he saw in that holy man, the better to copy his example and learn his spirit. He listened to his instructions with an insatiable ardour, and so deeply did he engrave them in his heart that the impressions remained vivid even in his old age.

      After Irenaeus had spent a number of years in combat against the eastern gnostics and philosophers of error, Saint Polycarp determined to send him to Gaul, where many of the heretics of Asia Minor had already migrated to pursue the Catholic religion, which was beginning to find roots there. With a company of about forty Christians, the valiant soldier of Christ ascended the Rhone to Lyons to rejoin and aid Saint Pothinus, its bishop. Saint Pothinus was already advanced in age, and his church's neophytes could not always distinguish truth from the gnostic aberrations. Saint Pothinus received the apostles with joy and soon ordained Saint Irenaeus.

      A hundred times he exposed himself to martyrdom by his zeal, acting as the right arm of the aging bishop, but God was reserving that crown for him twenty-five years later. When Saint Pothinus had glorified God by his splendid martyr's death in the year 177, Ireneus was chosen to be the second bishop of Lyons. The persecutors imagined that Christianity had been stifled in Lyons, and they ceased their pursuits for a time.

      This great Doctor of the Church wrote many important works, of which the most famous is his Adversus Haereses, Against the Heresies, in explanation of the Faith. By his preaching, Saint Irenaeus in a short time converted almost the whole country to the Faith; the Christians of Lyons became models by their candor, their estrangement from all ambition, their poverty, chastity and temperance, and in this way confounded many adversaries of their religion.

      Finally he suffered martyrdom there, with many others, in the year 202, under the Emperor Septimus Severus, after eighty years spent in the service of the Lord.

      — From Little Pictorial Lives of the Saints, a compilation based on Butler's Lives of the Saints, and other sources by John Gilmary Shea (Benziger Brothers: New York, 1894); Les Petits Bollandistes: Vies des Saints, by Msgr. Paul Guérin (Bloud et Barral: Paris, 1882), Vol. 7.