Besides the works and letters of Irenæus which we have mentioned, a certain book of his On Knowledge, written against the Greeks, very concise and remarkably forcible, is extant; and another, which he dedicated to a brother Marcian, In Demonstration of the Apostolic Preaching; and a volume containing various Dissertations, in which he mentions the Epistle to the Hebrews and the so-called Wisdom of Solomon, making quotations from them. These are the works of Irenæus which have come to our knowledge.
Commodus having ended his reign after thirteen years, Severus became emperor in less than six months after his death, Pertinax having reigned during the intervening time.