Anselm

An Italian from Aosta who wandered north to the Norman abbey of Bec, Anselm became its prior, its abbot, and finally archbishop of Canterbury in 1093 — an office he held through bruising conflicts with two English kings over the church's liberty. His motto, 'faith seeking understanding,' launched scholastic theology: the Proslogion argued from the idea of 'that than which nothing greater can be conceived' to God's existence, and Cur Deus Homo asked with new rigor why God became man. Exiled twice and recalled twice, he died in 1109, often reckoned the finest theological mind between Augustine and Aquinas.

His Proslogion argues that God, 'that than which nothing greater can be conceived,' must exist — the ontological argument philosophers still debate today.