The 13th cent. is generally regarded as the golden age of medieval philosophy. It was marked by two important developments: the growth of universities, especially at Paris and Oxford (see colleges and universities), and the introduction of Aristotle into the West. Until then, only the early works of Aristotle had been known to Western scholars, and those in poor translations; between 1120 and 1220 virtually the whole body of Aristotle's work was rendered into Latin, mainly from Arabic translations. The impact on Western thinkers of this vast body of systematic thought and organized research and analysis was enormous. Also important was the influence of Avicenna and Averroës, the two Arabic commentators whose interpretations of Aristotle were translated as well.
The Univ. of Paris became a leading center for the study of Aristotle and attracted scholars from all over Europe; the Dominicans and Franciscans, popular new religious orders, played a leading role in the expansion of the universities and the development of scholasticism. It was in the universities that the two traditional forms of scholastic literature were developed: the question (a thesis that is posed and defended against objections) and the commentary. Although Aristotle's work was of central significance in the development of scholasticism, it did not make its way without difficulties. In 1210 and 1215 papal authority prohibited the teaching of some of Aristotle's works at the Univ. of Paris, although by 1240 the ban was no longer enforced.
The first Western Aristotelian was Albertus Magnus, who was an important student of the natural sciences as well. But the leading figure in the movement to "Christianize Aristotle" was St. Thomas Aquinas, a Dominican and one of the greatest intellectual figures of the Middle Ages. He produced a vast body of philosophical work, which was remarkably precise, detailed, and organized. Denying any basic conflict between faith and reason, Aquinas sought to demonstrate that reason could lead man to many of the great spiritual truths and could help him to understand those truths that he accepted on faith. He combated secular interpretations of Aristotle, especially "Latin Averroism," the doctrines of Siger de Brabant. In particular, Aquinas attacked the Averroist teaching that denied the immortality of the individual soul.
Aquinas himself was vigorously opposed by the Franciscans, led by St. Bonaventure. Bonaventure, rooted in an older theological tradition, feared the excesses of reason in its contact with faith and almost succeeded in having Aquinas' teachings condemned at Paris. Another opponent of Aquinas was Duns Scotus, who developed a new scholastic synthesis. He argued that natural reason is limited in its ability to penetrate matters of faith, thus separating philosophy and theology.