Fides et Ratio §43

⁴³ A quite special place in this long development belongs to Saint Thomas, not only because of what he taught but also because of the dialogue which he undertook with the Arab and Jewish thought of his time. In an age when Christian thinkers were rediscovering the treasures of ancient philosophy, and more particularly of Aristotle, Thomas had the great merit of giving pride of place to the harmony which exists between faith and reason. Both the light of reason and the light of faith come from God, he argued; hence there can be no contradiction between them. More radically, Thomas recognized that nature, philosophy's proper concern, could contribute to the understanding of divine Revelation. Faith therefore has no fear of reason, but seeks it out and has trust in it. Just as grace builds on nature and brings it to fulfilment, so faith builds upon and perfects reason. Illumined by faith, reason is set free from the fragility and limitations deriving from the disobedience of sin and finds the strength required to rise to the knowledge of the Triune God. Although he made much of the supernatural character of faith, the Angelic Doctor did not overlook the importance of its reasonableness; indeed he was able to plumb the depths and explain the meaning of this reasonableness. Faith is in a sense an “exercise of thought”; and human reason is neither annulled nor debased in assenting to the contents of faith, which are in any case attained by way of free and informed choice. This is why the Church has been justified in consistently proposing Saint Thomas as a master of thought and a model of the right way to do theology. In this connection, I would recall what my Predecessor, the Servant of God Paul VI, wrote on the occasion of the seventh centenary of the death of the Angelic Doctor: “Without doubt, Thomas possessed supremely the courage of the truth, a freedom of spirit in confronting new problems, the intellectual honesty of those who allow Christianity to be contaminated neither by secular philosophy nor by a prejudiced rejection of it. He passed therefore into the history of Christian thought as a pioneer of the new path of philosophy and universal culture. The key point and almost the kernel of the solution which, with all the brilliance of his prophetic intuition, he gave to the new encounter of faith and reason was a reconciliation between the secularity of the world and the radicality of the Gospel, thus avoiding the unnatural tendency to negate the world and its values while at the same time keeping faith with the supreme and inexorable demands of the supernatural order”.