Series ForewordI. IntroductionEarly ChristologyInitial ProblemsJustin Martyr, Melito of Sardis, Irenaeus of Lyon, Tertullian of Carthage, Origen of AlexandriaFurther ProblemsThe Arians and Athanasius; Apollinaris of Laodicea; Theodore of Mopsuestia; Cyril, Nestorius, and Eutyches; Leo and ChalcedonII. Melito of SardisA Homily on the PassoverIII. Irenaeus of LyonAgainst HeresiesIV. TertullianAgainst PraxeasOn the Flesh of ChristV. OrigenOn First PrinciplesVI. AthanasiusOrations against the AriansVII. Apollinaris of LaodiceaOn the Union in Christ of the Body with the GodheadFragmentsVIII. Theodore of MopsuestiaFragments of the Doctrinal WorksIX. The Controversies Leading Up to the Council of ChalcedonNestorius's First Sermon against the TheotokosCyril of Alexandria's Second Letter to NestoriusNestorius's Second Letter to CyrilCyril's Letter to John of AntiochPope Leo I's Letter to Flavian of ConstantinopleThe Council of Chalcedon's "Definition of the Faith"Bibliography