Irenaeus of Lyon (fl. 180 C.E.): Bishop and historian of heresy. Neither his birth nor his death date is known, but he was old enough to have known the early martyr Polycarp. He became bishop of Lyon in 177/178, holding the post for perhaps twenty years. Some time before 190, he wrote his great work, the Adversus Hæreses, "Against Heresies." This describes most early Christian heresies; many of the sects would be completely unknown without it. Although he wrote in Greek, his work survives primarily in Latin, and there is some reason to think that the Biblical quotations in the Latin translation have been modified. Still, these quotations are very important, as they form an early witness to the so-called "Western" text of the Bible.