4 In the first place, philosophy, if rightly made use of by the wise, in a certain way tends to smooth and fortify the road to true faith, and to prepare the souls of its disciples for the fit reception of revelation; for which reason it is well called by ancient writers sometimes a steppingstone to the Christian faith,(6) sometimes the prelude and help of Christianity,(7) sometimes the Gospel teacher.(8) And, assuredly, the God of all goodness, in all that pertains to divine things, has not only manifested by the light of faith those truths which human intelligence could not attain of itself, but others, also, not altogether unattainable by reason, that by the help of divine authority they may be made known to all at once and without any admixture of error. Hence it is that certain truths which were either divinely proposed for belief, or were bound by the closest chains to the doctrine of faith, were discovered by pagan sages with nothing but their natural reason to guide them, were demonstrated and proved by becoming arguments. For, as the Apostle says, the invisible things of Him, from the creation of the world, are clearly seen, being understood by the things that are made: His eternal power also and divinity;(9) and the Gentiles who have not the Law show, nevertheless, the work of the Law written in their hearts.(10) But it is most fitting to turn these truths, which have been discovered by the pagan sages even, to the use and purposes of revealed doctrine, in order to show that both human wisdom and the very testimony of our adversaries serve to support the Christian faith-a method which is not of recent introduction, but of established use, and has often been adopted by the holy Fathers of the Church. What is more, those venerable men, the witnesses and guardians of religious traditions, recognize a certain form and figure of this in the action of the Hebrews, who, when about to depart out of Egypt, were commanded to take with them the gold and silver vessels and precious robes of the Egyptians, that by a change of use the things might be dedicated to the service of the true God which had formerly been the instruments of ignoble and superstitious rites. Gregory of NeoCaesarea(11) praises Origen expressly because, with singular dexterity, as one snatches weapons from the enemy, he turned to the defense of Christian wisdom and to the destruction of superstition many arguments drawn from the writings of the pagans. And both Gregory of Nazianzen(12) and Gregory of Nyssa(13)praise and commend a like mode of disputation in Basil the Great; while Jerome(14) especially commends it in Quadratus, a disciple of the Apostles, in Aristides, Justin, Irenaeus, and very many others. Augustine says: "Do we not see Cyprian, that mildest of doctors and most blessed of martyrs, going out of Egypt laden with gold and silver and vestments? And Lactantius, also and Victorinus, Optatus and Hilary? And, not to speak of the living, how many Greeks have done likewise?"(15) But if natural reason first sowed this rich field of doctrine before it was rendered fruitful by the power of Christ, it must assuredly become more prolific after the grace of the Saviour has renewed and added to the native faculties of the human mind. And who does not see that a plain and easy road is opened up to faith by such a method of philosophic study?
Source: Aeterni Patris (Vatican.va)