9 Just as it is the height of misfortune to go astray from the "Way," so is it to abandon the "Truth." Christ Himself is the first, absolute and essential "Truth," inasmuch as He is the Word of God, consubstantial and co-eternal with the Father, He and the Father being One. "I am the Way and the Truth." Wherefore if the Truth be sought by the human intellect, it must first of all submit it to Jesus Christ, and securely rest upon His teaching, since therein Truth itself speaketh. There are innumerable and extensive fields of thought, properly belonging to the human mind, in which it may have free scope for its investigations and speculations, and that not only agreeably to its nature, but even by a necessity of its nature. But what is unlawful and unnatural is that the human mind should refuse to be restricted within its proper limits, and, throwing aside its becoming modesty, should refuse to acknowledge Christ's teaching. This teaching, upon which our salvation depends, is almost entirely about God and the things of God. No human wisdom has invented it, but the Son of God hath received and drunk it in entirely from His Father: "The words which thou gayest me, 1 have given to them" (John XVII., 8). Hence this teaching necessarily embraces many subjects which are not indeed contrary to reason-for that would be an impossibility-but so exalted that we can no more attain them by our own reasoning than we can comprehend God as He is in Himself. If there be so many things hidden and veiled by nature, which no human ingenuity can explain, and yet which no man in his senses can doubt, it would be an abuse of liberty to refuse to accept those which are entirely above nature, because their essence cannot be discovered. To reject dogma is simply to deny Christianity. Our intellect must bow humbly and reverently "unto the obedience of Christ," so that it be held captive by His divinity and authority: "bringing into captivity every understanding unto the obedience of Christ" (2 Corinthians X., 5). Such obedience Christ requires, and justly so. For He is God, and as such holds supreme dominion over man's intellect as well as over his will. By obeying Christ with his intellect man by no means acts in a servile manner, but in complete accordance with his reason and his natural dignity. For by his will he yields, not to the authority of any man, but to that of God, the author of his being, and the first principle to Whom he is subject by the very law of his nature. He does not suffer himself to be forced by the theories of any human teacher, but by the eternal and unchangeable truth. Hence he attains at one and the same time the natural good of the intellect and his own liberty. For the truth which proceeds from the teaching of Christ clearly demonstrates the real nature and value of every being; and man, being endowed with this knowledge, if he but obey the truth as perceived, will make all things subject to himself, not himself to them; his appetites to his reason, not his reason to his appetites. Thus the slavery of sin and falsehood will be shaken off, and the most perfect liberty attained: "You shall know the truth, and the truth shall make you free" (John VIII., 32). It is, then, evident that those whose intellect rejects the yoke of Christ are obstinately striving against God. Having shaken off God's authority, they are by no means freer, for they will fall beneath some human sway. They are sure to choose someone whom they will listen to, obey, and follow as their guide. Moreover, they withdraw their intellect from the communication of divine truths, and thus limit it within a narrower circle of knowledge, so that they are less fitted to succeed in the pursuit even of natural science. For there are in nature very many things whose apprehension or explanation is greatly aided by the light of divine truth. Not unfrequently, too, God, in order to chastise their pride, does not permit men to see the truth, and thus they are punished in the things wherein they sin. This is why we often see men of great intellectual power and erudition making the grossest blunders even in natural science.
Source: Tametsi Futura Prospicientibus (Vatican.va)