5 But the advantage to be derived from such a school of philosophy is not to be confined within these limits. The foolishness of those men who "by these good things that are seen could not understand Him, that is, neither by attending to the works could have acknowledged who was the workman,"(16) is gravely reproved in the words of Divine Wisdom. In the first place, then, this great and noble fruit is gathered from human reason, that it demonstrates that God is; for the greatness of the beauty and of the creature the Creator of them may be seen so as to be known thereby.(17) Again, it shows God to excel in the height of all perfections, especially in infinite wisdom before which nothing lies hidden, and in absolute justice which no depraved affection could possibly shake; and that God, therefore, is not only true but truth itself, which can neither deceive nor be deceived. Whence it clearly follows that human reason finds the fullest faith and authority united in the word of God. In like manner, reason declares that the doctrine of the Gospel has even from its very beginning been made manifest by certain wonderful signs, the established proofs, as it were, of unshaken truth; and that all, therefore, who set faith in the Gospel do not believe rashly as though following cunningly devised fables,(18) but, by a most reasonable consent, subject their intelligence and judgment to an authority which is divine. And of no less importance is it that reason most clearly sets forth that the Church instituted by Christ (as laid down in the Vatican Council), on account of its wonderful spread, its marvellous sanctity, and its inexhaustible fecundity in all places, as well as of its Catholic unity and unshaken stability, is in itself a great and perpetual motive of belief and an irrefragable testimony of its own divine mission.(19)
Source: Aeterni Patris (Vatican.va)