(Gr. = “of the same substance”). This technical term from late Greek philosophical tradition was first used in a Christian setting by Gnostics. Both Origen in Alexandria and Sabellius in Rome played some role in its adoption in Christianity. Tertullian was ultimately responsible for its reappropriation, though as late as the Synod of Antioch (268) homoousios was severely criticized. That Arius himself opposed the term is evident in his letter to Alexander, bishop of Alexandria, before the Council of Nicea* (325). Evidently it was the emperor Constantine as presiding officer there, presumably on the advice of Hosius* of Cordova, who introduced the concept into creedal discussions, with reference to the relationship between Father and Son.