St. Irenaeus was an early Church Father in the 2nd century. He was mentored by St. Polycarp, himself a disciple of St. John the Evangelist. St. Irenaeus became Bishop of Lyons and fulfilled his calling as a prolific writer. Most notably, he defended the faith against the intellectual imperialism of the Gnostics; refuting their claims by defining truth as available to all. He said truth is public, unifying, and pneumatic (permeating). Additionally, St. Irenaeus helped identify the canon of scripture and the creed.