He was by birth a Jew and belonged to the church of Jerusalem but lived in Rome almost twenty years until 177 when he returned into the East. In 133, he wrote a History of the Church in five books, from the passion of Christ down to his own time. In it he gave illustrious proofs of his faith and showed the apostolic tradition and that, although certain men had disturbed the church by broaching heresies, down to his time no Episcopal see or particular church had fallen into error but had preserved the truths delivered by Christ. This testimony he gave after having personally visited all the principal churches both of the East and West.