He was born in the Italian city of Aosta in 1033. After studying rhetoric and Latin, he entered as Benedictine in the Norman monastery of Bec in 1060, from which he was elected abbot in 1078. There he achieved just fame as a philosopher thanks to his teaching and publication of Monologion and Proslogion, where he made the famous ontological argument.

In 1093 he was appointed archbishop of Canterbury, a ministry he exercised until his death in 1109. During this stage he had to reconcile his intellectual vocation with his task of government, in order to preserve the freedom and unity of the Church against the interests of the State .