Anselm of Canterbury
Saint Anselm of Canterbury (b. 1033; d. April 21, 1109) was one of the most important Christian philosophers of the eleventh century, also called the Scholastic Doctor for founding scholasticism. St. Anselm is famous for the first formal presentation of the ontological argument, which was a highly influential proof of the existence of God based on definition of God. A Latin scholar, a monk and the Archbishop of Canterbury, England, St. Anselm produced great works in defense of Christ. He became a Doctor of the Church by Pope Clement XI in 1720.
St. Anselm was born to noble parents at Aosta, Italy. His father Gundulph was born a Lombard and was noted for overwhelming presence and harsh temper. His pious mother Ermenberga, took care to give him an early tincture of piety, and the impressions her instructions made upon him were as lasting as his life.  At age 15, he requested to enter the monastery. His father would not approve and the abbot fearing the father's displeasure, refused to accept him. The rejection didn't seem to effect young Anselm as he went on in life as a nobleman. During this time his mother died. He studied for a time in Burgundy, then went on to the school of Bec in Normandy, which was under the direction of the renowned Lanfranc.  On his father's death Anselm consulted his superior as to whether he should return to Italy and manage the estates he had inherited, or remain in France and enter the Church. On the advice of Lanfranc he became a monk. Lanfranc became abbot of St. Stephen's and Anselm was rapidly promoted to prior of Bec. During his leadership, the monastery grew in both reputation and wealth. After the Norman Conquest had acquired considerable property in England, it became the duty of Anselm to visit this property occasionally. The people of England fell in love with Anselm that he was looked upon as the natural successor to Lanfranc as Archbishop of Canterbury.
Anselm became the most learned theologian of his generation. His writings are regarded as the best since St. Augustine. Anselm's predecessors would assume out of faith that the fundamental principle of the God whom they loved and worshiped had real existence. Anselm's approach would be very different. He never doubted, he nevertheless wished to satisfy his mind with proof. "I do not seek to understand in order that I may believe, but I believe in order to understand. For this too I believe, that unless I first believe, I shall not understand." His great understanding led to such explanations as the aspects and the unity, our knowledge and understanding of the divine nature, the complex nature of the will and its involvement in free choice, the interworkings of human will and actions of divine grace, the nature of truth and justice, the nature and origins of virtues and vices, the nature of evil as negation plus the condition and implications of original sin. Anselm also authored a number of other arguments for the existence of God, based on cosmological and teleological grounds.
Archbishop of Canterbury
Upon Lanfranc's death, king William Rufus II seized the possessions of Lanfranc and offered no replacement. About four years later in 1092, at the invitation of Hugh, Earl of Chester, Anselm crossed to England but was refused permission by the king. The following year king William fell ill and feared death was near. Eager to reconcile his sin, he nominated Anselm to the vacant see in Canterbury and was consecrated Archbishop in 1093. This would be the beginning of strain between Anselm and English kings. The King would refuse Anselm from leaving England to visit Rome. King William would refuse to recognize Pope Urban in the schism of anti-Popes. When Anselm finally did receive permission to visit Rome, the king seized all revenues and assets of his archbishopric. In 1100, king William was killed and his successor king Henry I, at once invited Anselm to return to England. Life under king Henry would be no easier. Henry refused to give back possessions seized by King William. Conflict over lay investiture now broke out and Anselm refused to consecrate bishops and abbots nominated by the king.  Once again, Anselm was banished while appealing to Rome. During this period, Anselm would attend the Council of Bari (1098) Anselm ably defended the Filioque of the creed in the East-West controversy on the procession of the Holy Spirit. Also, was opposed to the Crusades. The long dispute as to investiture was finally settled with a compromise in 1107. Henry relinquished his right to invest his bishops and abbots, Anselm was allowed to return to England. He remained in his bishopric until he died two years later in 1109.
- Cur Deus Homo (Why did God become Man?")
- Monologion (rational proofs for God's existence )
- Proslogion (ontological proof, God's existence of a perfect being in whom nothing is lacking)
- De Fide Trinitatis (defended universals against the nominalist Roscelin)
- De Conceptu Virginali (the Immaculate Conception of Mary)
- Epistola de Incarnatione Verbi (the Incarnation of the Word)
- De Conceptu Virginali et de Originali Peccato (on the Virgin Conception and Original Sin)
- De Processione Spiritus Sancti (on the Procession of the Holy Spirit
- De Casu Diaboli (problem of the origin of evil and divine responsibility for evil)
- De Libertate Arbitrii (human will and its relation to justice or rightness of will)
- De Veritate (a correspondence theory of truth)
- De Grammatico (focuses on solving some problems of language, qualities, and substances)