12 Quadratus, also, and Aristides, Hermias, and Athenagoras stood nobly forth in that time. Nor did Irenaeus, the invincible martyr and Bishop of Lyons, win less glory in the same cause when, forcibly refuting the perverse opinions of the Orientals, the work of the Gnostics, scattered broadcast over the territories of the Roman Empire, he explained (according to Jerome) the origin of each heresy and in what philosophic source it took its rise.(29) But who knows not the disputations of Clement of Alexandria, which the same Jerome thus honorably commemorates: "What is there in them that is not learned, and what that is not of the very heart of philosophy?"(30) He himself, indeed, with marvellous versatility treated of many things of the greatest utility for preparing a history of philosophy, for the exercise of the dialectic art, and for showing the agreement between reason and faith. After him came Origen, who graced the chair of the school of Alexandria, and was most learned in the teachings of the Greeks and Orientals. He published many volumes, involving great labor, which were wonderfully adapted to explain the divine writings and illustrate the sacred dogmas; which, though, as they now stand, not altogether free from error, contain nevertheless a wealth of knowledge tending to the growth and advance of natural truths. Tertullian opposes heretics with the authority of the sacred writings; with the philosophers he changes his fence and disputes philosophically; but so learnedly and accurately did he confute them that he made bold to say: "Neither in science nor in schooling are we equals, as you imagine."(31) Arnobius, also, in his works against the pagans, and Lactantius in the divine Institutions especially, with equal eloquence and strength strenuously strive to move men to accept the dogmas and precepts of Catholic wisdom, not by philosophic juggling, after the fashion of the Academicians, but vanquishing them partly by their own arms, and partly by arguments drawn from the mutual contentions of the philosophers.(32) But the writings on the human soul, the divine attributes, and other questions of mighty moment which the great Athanasius and Chrysostom, the prince of orators, have left behind them are, by common consent, so supremely excellent that it seems scarcely anything could be added to their subtlety and fulness. And, not to cover too wide a range, we add to the number of the great men of whom mention has been made the names of Basil the Great and of the two Gregories, who, on going forth from Athens, that home of all learning, thoroughly equipped with all the harness of philosophy, turned the wealth of knowledge which each had gathered up in a course of zealous study to the work of refuting heretics and preparing Christians.
Source: Aeterni Patris (Vatican.va)