Church History by Eusebius Pamphilius
Chapter X.--The Bishops of Rome and of Alexandria during the Reign of Antoninus.
Adrian having died after a reign of twenty-one years, was succeeded in the government of the Romans by Antoninus, called the Pious. In the first year of his reign Telesphorus died in the eleventh year of his episcopate, and Hyginus became bishop of Rome. Irenæus records that Telesphorus' death was made glorious by martyrdom, and in the same connection he states that in the time of the above-mentioned Roman bishop Hyginus, Valentinus, the founder of a sect of his own, and Cerdon, the author of Marcion's error, were both well known at Rome. He writes as follows: