Irenæus, a presbyter under Pothinus the bishop who ruled the church of Lyons in Gaul, being sent to Rome as legate by the martyrs of this place, on account of certain ecclesiastical questions, presented to Bishop Eleutherius certain letters under his own name which are worthy of honour. Afterwards when Pothinus, nearly ninety years of age, received the crown of martyrdom for Christ, he was put in his place. It is certain too that he was a disciple of Polycarp, the priest and martyr, whom we mentioned above.
He wrote five books Against heresies and a short volume, Against the nations and another On discipline, a letter to Marcianus his brother On preaching, a book of Various treatises; also to Blastus, On schism, to Florinus On monarchy or That God is not the author of evil, also an excellent Commentary on the Ogdoad at the end of which indicating that he was near the apostolic period he wrote “I adjure you whosoever shall transcribe this book, by our Lord Jesus Christ and by his glorious advent at which He shall judge the quick and the dead, that you diligently compare, after you have transcribed, and amend it according to the copy from which you have transcribed it and also that you shall similarly transcribe this adjuration as you find it in your pattern.”
Other works of his are in circulation to wit: to Victor the Roman bishop On the Paschal controversy in which he warns him not lightly to break the unity of the fraternity, if indeed Victor believed that the many bishops of Asia and the East, who with the Jews celebrated the passover, on the fourteenth day of the new moon, were to be condemned. But even those who differed from them did not support Victor in his opinion. He flourished chiefly in the reign of the Emperor Commodus, who succeeded Marcus Antoninus Verus in power.
Source: De Viris Illustribus (Illustrious Men) (New Advent)