Summa summae S. Thomae, Tomus III

[Now we have observed that the object of revelation can be either truths of an order superior to human reason, such as we have said the mysteries are, or those things which unaided man can in no way come to know about God, as well as those things which, although revealed, fall within the limits of human reason.

* A twofold necessity is understood in this matter, namely an absolute necessity, founded upon the total incapacity of human reason to attain the knowledge of truths of a certain kind, and a moral necessity, which supposes only a great difficulty in sufficiently understanding truths of another kind.

This twofold distinction being laid down,

I say 1°: Divine revelation was absolutely necessary in order that man might know supernatural truths. And this necessity is only hypothetically absolute, as is plain, namely supposing the supernatural end bestowed on man by God, which God fixed according to his good pleasure which he purposed in him, as the Apostle says, Ephes., I, 9.

Proof. from St. Thomas, I Contra gentes, cap. 5|summa-contra-gentiles-liber-primus:liber.1/capitulum.5 : « Because, he says, men are ordered by divine providence to a higher good than human frailty can experience in the present life, it was necessary that the mind be summoned to something higher than our reason can at present reach, that so it might learn to desire something, and by earnest striving tend toward something that exceeds the whole state of the present life... » It is also necessary that a truth of this kind be set before men to be believed, in order that they may hold a truer knowledge of God. For then only do we truly know God when we believe him to be above everything that it is possible for man to think about God, since the divine substance exceeds the natural knowledge of man. Therefore, through the fact that certain things about God are proposed to man that exceed reason, there is confirmed in man the conviction that God is something above what can be thought... » And therefore, although human reason cannot fully grasp those things that are above reason, yet much perfection is acquired if it holds them at least in some manner by faith. And so it is said : Many things beyond the sense of man have been shown thee, Eccli., III, 25. And : The things that are of God no man knows, but the Spirit of God... But to us God hath revealed them by his Spirit, 1 Cor., II, 10 and 11. »

The Vatican Council asserts this hypothetically absolute necessity, constit. Dei Filius, chap. 2, on Revelation. After teaching that by divine revelation natural truths « can be known with firm certitude and with no admixture of error, » it adds : « Not for this cause, however, must revelation be called absolutely necessary, but because God of his infinite goodness ordained man to a supernatural end, namely to partake of the divine goods that altogether surpass the understanding of the human mind, since eye hath not seen, nor ear heard, neither hath it entered into the heart of man, what things God hath prepared for them that love him, 1 Cor., II, 9. »

Since the knowledge of truths that exceed the natural grasp of human reason was granted to man only in view of the supernatural end prefixed to us by God, it follows that this end holds logically the first place among truths of this kind, if you except the existence of God, which, as will be said below, belongs at once primarily to reason and secondarily to faith. This Paul testifies, ad Hebr., XI, 6, saying : He that cometh to God must believe that he is, and is a rewarder to them that seek him. Afterwards come the mysteries that manifest either the intimate life of God, whose contemplation we enjoy in heaven, namely the Trinity; or the means by which God leads man back, gone astray from his supernatural end through original sin, to this end, namely the incarnation of the Word and redemption, as also the Church, the sacraments and other things of this kind pertaining to the fitting and true worship of God : all which man instructed solely by the natural light would not even have suspected.

I say 2°: Divine revelation was morally necessary in order that man might be able to know natural truths with firm certitude and with no admixture of error.

Proof. 1° from holy Scripture. Sap., XIII, 1, 2, 6, 7, 10 : Vain are all men in whom there is not the knowledge of God, and who could not from the things that are seen understand him that is, nor, attending to the works, acknowledge who was the workman : but they deemed either fire, or spirit, or the swift air, or the circle of stars, or the great water, or the sun and moon, to be gods the rulers of the world... For these perhaps err, seeking God and wishing to find him. For while they converse among his works, they search, and are persuaded that the things seen are good... But wretched are they, and among the dead is their hope, who called the works of men's hands gods... and the likeness of living creatures. Thereupon, most charmingly demonstrating the absurdity of idolatry, the wise man enumerates and pierces with the sharpest marks the manifold crimes born of it. Rom., I, 18-22 : The wrath of God is revealed from heaven against all impiety and injustice of those men who detain the truth of God in injustice, because that which is known of God is manifest in them; for God hath manifested it to them. His invisible things, from the creation of the world, are seen, being understood by the things that are made, also his everlasting power and divinity : so that they are inexcusable; because, having known God, they did not glorify him as God, or give thanks, but became vain in their thoughts, and their foolish heart was darkened; for professing themselves to be wise, they became fools. Here the Apostle, having asserted natural revelation through reason, shows it to have been wholly insufficient for men to stand fast in the true knowledge of God and exhibit to him fitting worship : whence the moral necessity of a new and supernatural revelation is demonstrated, as also in the preceding text. Many other testimonies from sacred letters could be drawn forth.

Proof. 2° from the Council of Trent, sess. v, canons 1 and 2 : « If anyone shall not confess that the first man Adam, when he had transgressed the commandment of God in paradise, immediately lost the holiness and justice in which he had been constituted..., and that the whole Adam, through the offense of prevarication, was changed for the worse in body and soul; let him be anathema. » — « If anyone shall assert that the prevarication of Adam harmed himself alone, and not his posterity...; let him be anathema. » From these it follows that Adam and his posterity lost through sin not only the supernatural gifts, but were also « changed for the worse » in the faculties and powers inherent in nature itself, and consequently in natural intellect and reason; whence, left to themselves, they can no longer perceive even natural truths with sufficient clearness, nor know them with firm certitude and no admixture of error.

Proof. 3° from the reasons excellently drawn out by the Angelic Doctor, I Contra gentes, cap. 4|summa-contra-gentiles-liber-primus:liber.1/capitulum.4 : « This, he says, must be shown concerning that truth which can lie open to the inquiry of reason : lest perchance it seem to anyone that, since reason can be had of it, it was in vain handed over to be believed by supernatural inspiration. » Three inconveniences would nevertheless follow if a truth of this kind were left to be sought out by reason alone.

» The first is that the knowledge of God would be present in few men. For very many are hindered from the fruit of diligent inquiry, which is the finding of truth, for three reasons.

» Some indeed are hindered by the indisposition of their temperament, from which many are naturally indisposed to knowing. Hence by no study could they attain the point of reaching the highest degree of human cognition, which consists in knowing God.

» Others, however, are hindered by the necessity of domestic affairs. For there must be among men some who devote themselves to administering temporal things, and these could not spend so much time in the leisure of contemplative inquiry as to reach the highest summit of human inquiry, namely the knowledge of God.

» Still others are hindered by sloth. For the knowledge of those things which reason can investigate concerning God requires that many things be known beforehand, since the consideration of almost the whole of philosophy is ordered to the knowledge of God. On account of which metaphysics, which deals with divine things, remains the last to be learned among the parts of philosophy. Thus, then, one can arrive at the inquiry of the aforesaid truth only with great labor of study : which labor few are willing to undertake for the love of science, whose natural appetite God nevertheless implanted in the minds of men.

» The second inconvenience is that those who would arrive at the knowledge or discovery of the aforesaid truth would reach it scarcely after a long time, both on account of the profundity of such a truth, for the grasping of which by the way of reason the human intellect is found adequate only after long exercise; and also on account of the many things presupposed, as was said; and further because, in the time of youth, while the soul fluctuates amid the various motions of the passions, it is not apt for the cognition of so lofty a truth, but becomes prudent and knowing in quietness, as is said in VII Physicorum, c. 3. The human race, therefore, if only the way of reason lay open for knowing God, would remain in the darkest shadows of ignorance, since the knowledge of God, which makes men most perfect and good, would accrue only to a few, and even to these few only after a long lapse of time.

» The third inconvenience is that falsity is for the most part mixed into the investigation of human reason, on account of the weakness of our intellect in judging and the admixture of phantasms. And hence among many there would remain in doubt those things which are most truly demonstrated, so long as they are ignorant of the force of demonstration, and especially when they see different things taught by different persons who are called wise. Among the many true things that are demonstrated, something false is sometimes mixed in which is not demonstrated, but asserted by some probable or sophistical argument, which is sometimes taken for demonstration. And therefore it was necessary that, through the way of faith, with fixed certitude, the very truth concerning divine things be set before men.

» Divine clemency therefore provided wholesomely, in commanding that even those things which reason can investigate be held by faith, so that thus all could easily become partakers of the divine knowledge, without doubt and error.

» Whence it is said : Walk you no longer as also the Gentiles walk, in the vanity of their own sense, having the understanding darkened, Ephes., IV, 17 and 18. And : All thy children shall be taught of the Lord, Is., LIV, 13. »

The same the Vatican Council teaches, constit. Dei Filius, chap. 2, on Revelation : « Holy Mother Church holds and teaches that God, the beginning and end of all things, can be certainly known from created things by the natural light of human reason ; for his invisible things are seen, being understood by the things that are made, from the creation of the world, Rom., I, 20 : nevertheless it has pleased his wisdom and goodness to reveal to the human race other things, and those by a supernatural way, himself and the decrees of his eternal will, the Apostle saying : God, who at sundry times and in divers manners spoke in times past to the fathers by the prophets, last of all in these days hath spoken to us by his Son, Hebr., I, 1. » To this divine revelation indeed it must be attributed that those things which in divine matters are not of themselves impervious to human reason, even in the present condition of mankind, can be known by all readily, with firm certitude and with no admixture of error. » In the present condition, therefore, namely with the human intellect weakened and not little obscured by sin, unless divine revelation illumined and strengthened it, human reason would know, not readily, not with firm certitude, and with much admixture of error, even those things which in divine matters are not of themselves impervious to it. Whence arises the moral necessity of divine revelation. What the notes of divine and supernatural revelation are, was said in the treatise de Fide, dissert. II, where the prophecies of the prophets, the miracles, and the wonderful and plainly divine manner in which the Religion of Christ was founded and propagated are assigned as motives of credibility.]