Saint Thomas Aquinas

More successfully than any other theologian or philosopher, Aquinas organized the knowledge of his time in the service of his faith. In his effort to reconcile faith with intellect, he created a philosophical synthesis of the works and teachings of Aristotle and other classic sages; of Augustine and other church fathers; of Averroës, Avicenna, and other Islamic scholars; of Jewish thinkers such as Maimonides and Solomon ben Yehuda ibn Gabirol; and of his predecessors in the Scholastic tradition. This synthesis he brought into line with the Bible and Roman Catholic doctrine.

Aquinas's accomplishment was immense; his work marks one of the few great culminations in the history of philosophy. After Aquinas, Western philosophers could choose only between humbly following him and striking off in some altogether different direction. In the centuries immediately following his death, the dominant tendency, even among Roman Catholic thinkers, was to adopt the second alternative. Interest in Thomist philosophy began to revive, however, toward the end of the 19th century. In the encyclical Aeterni Patris (Of the Eternal Father, 1879), Pope Leo XIII recommended that St. Thomas's philosophy be made the basis of instruction in all Roman Catholic schools. Pope Pius XII, in the encyclical Humani Generis (Of the Human Race, 1950), affirmed that the Thomist philosophy is the surest guide to Roman Catholic doctrine and discouraged all departures from it. Thomism remains a leading school of contemporary thought. Among the thinkers, Roman Catholic and non-Roman Catholic alike, who have operated within the Thomist framework have been the French philosophers Jacques Maritain and Étienne Gilson.

St. Thomas was an extremely prolific author, and about 80 works are ascribed to him. The two most important are Summa Contra Gentiles (1261-1264) and Summa Theologica (1265-1273). Summa Contra Gentiles, which has been translated into English as On the Truth of the Catholic Faith (1956), is a closely reasoned treatise intended to persuade intellectual Muslims of the truth of Christianity. Summa Theologica, which has been republished frequently in Latin and vernacular editions under its Latin title, was written in three parts (on God, on the moral life, and on Christ) and was intended to set forth Christian doctrine for beginners. The last part remained unfinished at his death.