(130-202) Author of "Against Heresies" and other works. He was a main proponent against Gnosticism and is responsible for the early formation of Orthodox Christianity. He became Pope, (Bishop of Rome) after winning the position over Valentinus. He claimed Apostolic succession from having studied from Polycarp. (See "The Early Church", Chadwick, Penquin, 1993. See also; New Advent,