Against Heresies (Adversus Haereses)
Saint Irenaeus of Lyons · c. 180 AD
Ante-Nicene Fathers (Roberts–Donaldson), Roberts, Donaldson, and Coxe (eds.), Ante-Nicene Fathers, Buffalo: Christian Literature Publishing, 1885–1887; digitized by CCEL.
Disciple of St Polycarp of Smyrna (himself a disciple of St John the Theologian); bishop of Lugdunum (Lyons) in Gaul; the foundational ante-Nicene theologian and the great refuter of Gnostic heresy. His Against Heresies in five books is the cornerstone of pre-Nicene doctrine on the unity of God, the recapitulation of all things in Christ, and the rule of faith handed down by apostolic succession.