10 If, venerable brethren, you open the history of philosophy, you will find all We have just said proved by experience. The philosophers of old who lacked the gift of faith, yet were esteemed so wise, fell into many appalling errors. You know how often among some truths they taught false and incongruous things; what vague and doubtful opinions they held concerning the nature of the Divinity, the first origin of things, the government of the world, the divine knowledge of the future, the cause and principle of evil, the ultimate end of man, the eternal beatitude, concerning virtue and vice, and other matters, a true and certain knowledge of which is most necessary to the human race; while, on the other hand, the early Fathers and Doctors of the Church, who well understood that, according to the divine plan, the restorer of human science is Christ, who is the power and the wisdom of God,(27) and in whom are hid all the treasures of wisdom and knowledge,(28) took up and investigated the books of the ancient philosophers, and compared their teachings with the doctrines of revelation, and, carefully sifting them, they cherished what was true and wise in them and amended or rejected all else. For, as the all-seeing God against the cruelty of tyrants raised up mighty martyrs to the defense of the Church, men prodigal of their great lives, in like manner to false philosophers and heretics He opposed men of great wisdom, to defend, even by the aid of human reason, the treasure of revealed truths. Thus, from the very first ages of the Church, the Catholic doctrine has encountered a multitude of most bitter adversaries, who, deriding the Christian dogmas and institutions, maintained that there were many gods, that the material world never had a beginning or cause, and that the course of events was one of blind and fatal necessity, not regulated by the will of Divine Providence.
Source: Aeterni Patris (Vatican.va)