Photios I of Constantinople

Born around 815 into a noble Constantinopolitan family thick with patriarchs, Photios abandoned plans for monastic life and became the leading scholar of his age. In 858, Emperor Michael III forced Patriarch Ignatius out and installed Photios — still a layman — into the seat, triggering power struggles with Rome that would define centuries. He was central to converting the Slavs to Christianity and compiled the classic source of church law for the Greek Church, a systematizing effort that mirrored Gratian's work in the West. Ignatius was reinstated; when he died in 877, Photios resumed the pat…