Over the centuries various people in the Church have become outstanding for many and various reasons. Some build, some write beautiful music, others win barbarian hordes for Christ. Sometimes, some just think!
St. Anselm was one of those, he is considered by many to be the most important Christian theologian in the West between Augustine and Thomas Aquinas. That is pretty heady company. Two of Anselm's greatest works are the Proslogium (A Discourse) and the Cur Deus Homo? (Why did God become human?).
In the Proslogium, Anslem explains that God is "that than which nothing greater can be thought", he then argues that what exists in reality is greater than that which is only in the mind; wherefore, since "God is that than which nothing greater can be thought", He exists in reality.
In the Cur Deus Homo?, Anselm puts forward the "satisfaction theory" of the Atonement. Man's offence of rebellion against God is one that demands a payment or satisfaction. Fallen man is incapable of making adequate satisfaction, and so God took human nature upon Him, in order that a perfect man might make perfect satisfaction and so restore the human race. The success of his work may be gauged by the fact that many Christians today not only accept his way of explaining the Atonement, but are simply unaware that there is any other way to understand Atonement.
Anselm was born about 1033 in Italy. We don't know much about his early life, but we do know that he left home at about twenty-three, and roamed around Burgundy and France for three years. There is a story that even as a boy, eh wanted to become a Monk, but his father refused to allow it. Anselm arrived in Normandy in 1059, and his interest was immediately focused on the Benedictine abbey at Bec. This Abbey had a widely known school which was under the direction of Stephen Lanfranc, the abbey's prior. In 1060 Anselm entered the Abbey as a novice. His intellectual and spiritual gifts brought him rapid advancement, and when Lanfranc was appointed abbot of Caen in 1063, Anselm was elected to succeed him as prior.
The Abbey had possessions in England, which required Anselm to frequently travel there. His old Master, Stephen Lanfranc had become the Archbishop of Canterbury, and when he died, Anslem was the general choice to replace him in 1089. However, the king of England at that time, William III, preferred to keep the office vacant. This would allow him to keep the revenues of Canterbury for his own use. Then in 1093, the king fell gravely ill, and during his illness, he promised to let Anselm be enthroned as Archbishop. When the King recovered, he tried to renege on his agreements, and the two began to dispute the extent of the King's right to intervene in Church affairs. Eventually Anselm had to go into exile in Italy until the king died 1100.
Anselm used his time of exile to work out a conflict on the Creed with some Greek bishops in southern Italy, and finish his work known as Cur Deus Homo? He returned to England, under the new king Henry I. But Henry was as determined as William had been on maintaining royal jurisdiction over the Church, and Anselm was again exiled from 1103 to 1107. In 1107 a compromise was reached, and Anselm returned home to Canterbury, where he lived his last few years in peace, dying 21 April 1109.
Almighty God, Who raised up Your servant Anselm to teach the Church of his day to understand its faith in Your eternal Being, perfect justice, and saving mercy: Provide Your Church in every age with devout and learned scholars and teachers, that we may be able to give a reason for the hope that is in us; through Jesus Christ our Lord, Who lives and reigns with You and the Holy Spirit, one God, for ever and ever.