132. The documents of the Church which bear on this point are chiefly recalled to these: 1) The Supreme Pontiff Pius IX (Qui pluribus, encyclical, November 9, 1846) says: “Nor surely with lesser fallacy would those enemies of divine revelation, extolling human progress with the highest praises, wish with rash and plainly sacrilegious daring to introduce it into the Catholic religion, just as if religion itself were not the work of God, but of men, or some philosophical invention which can be perfected by human methods. Upon those who so miserably rave falls very fittingly what Tertullian deservedly reproached to the philosophers of his own time, ‘who brought forth a Stoic, and Platonic, and Dialectic Christianity.’” 2) Hence proposition 5 condemned in the Syllabus: “Divine revelation is imperfect, and therefore subject to a continual and indefinite progress which corresponds to the progression of human reason.” 3) But the Vatican Council (Dei Filius, ch. 4) says: “For the doctrine of faith which God revealed was not proposed to human talents as a philosophical invention to be perfected, but was handed over as a divine deposit to the Spouse of Christ, to be faithfully guarded and infallibly declared. Hence that meaning of sacred dogmas also must perpetually be retained which holy Mother Church has once declared, nor must one ever recede from that meaning under the appearance and name of a higher understanding.” 4) And (can. 3 in ch. 2): “If anyone shall say that man cannot be divinely elevated to knowledge and perfection which surpasses the natural, but from himself can and ought, by continual progress, finally to attain to the possession of all truth and good, let him be anathema.”
133. In order that the state of the question may be well understood, a twofold error must be distinguished here. One is that of those who, while admitting revelation at least in name, so subject it to reason that it must be accommodated to reason. But since, they say, human reason lies under the law of continual progress, according to different ages it understands and explains revealed truths in different ways; and therefore, as science progresses, one must recede from the meaning of those truths once received. Against this error we do not dispute directly in the present question, both because it supposes revelation, whose existence has not yet been proved here, and because we sufficiently refuted it in the treatise On the Infused Virtues, where we also demonstrated true progress in faith (n. 515 ff.). The other error is that of those who introduce the progress of human reason for this purpose, that they may exclude the necessity of revelation which we established in the preceding thesis. For if, they say, any excellence appears in the Christian religion above preceding religions, it must be attributed not to revelation, but to the progress of reason; or if there was or still is any ignorance as regards religion, it must be dispelled not necessarily through revelation, but through the continual progress of reason itself. We undertake here to refute this error, with this purpose also, that the necessity of revelation may be better confirmed.
134. Nevertheless it will help to set forth certain things beforehand, so that the discussion may proceed clearly. And first, the word progress, derived from the verb gradior and the preposition prae, properly signifies a step or movement toward the forward part; whence Tully said (On Duties, book 1, c. 1): “and he is not ignorant of their advances and, as it were, anticipations.” Therefore he progresses who proceeds further, just as he is said to regress who steps backward. But figuratively progress is taken for the fruit which we make while devoting effort to some matter: “The chief men of philosophy itself,” says Cicero (Tusculan Questions, book 4), “could never have made such great progress in their studies without a burning desire.” Hence also someone is commonly said to progress in letters, sciences, virtue, piety, etc., when he makes fruit in them or advances. From this signification of the word progress each person gathers: 1) that progress indeed imports movement or change, but that not every change is progress. For there can be movement which is not toward the forward part, by which we do not proceed further, which is not a change for the better. 2) That in every progress something is supposed which remains unchanged. For someone would not be said to progress, or to be moved toward the forward part, or to be changed for the better, unless he were the same one who before was behind and now is ahead, who now has himself better than before. This indeed is proper to any change properly so called. “It belongs to the nature of change,” says St. Thomas (I, q. 45, a. 2, ad 2), “that something the same should have itself otherwise now and before. For sometimes it is the same being in act having itself otherwise now and before, as in movements according to quantity and quality; but sometimes it is the same being in potency only, as in change according to substance, whose subject is matter.” And (Contra Gentiles, book 2, c. 12) he says: “In every change or movement there must be something having itself otherwise now than before; for the very name of change shows this.”
135. Hence St. Augustine, who often teaches that all created things are subject to change, teaches at the same time that there is something in them which always remains the same. Thus, for example, he writes (On Psalm 121, n. 6): “What a body has is not the selfsame, because it does not stand in itself. It is changed through ages, it is changed through changes of places and times, it is changed through diseases and bodily defects; therefore it does not stand in itself. Heavenly bodies do not stand in themselves; they have certain changes of their own, even if hidden ones. Certainly they are changed from places to places; they ascend from the East into the West, and again go round to the East. Therefore they do not stand, nor are they the selfsame. The human soul itself does not stand. For by how many changes and thoughts it is varied, by how many pleasures it is altered, by how many desires it is struck and torn apart. The very mind of man which is called rational is changeable, nor is it the selfsame. At one time it wills, at another it does not will; at one time it knows, at another it does not know; at one time it remembers, at another it forgets. Therefore it does not have the selfsame from itself.” These things indeed are directly about the change of all things, which at the same time indirectly, as is plain to the reader, show that something unchanged remains. But Augustine also teaches this other point directly more than once. Thus (Soliloquies, book 2, c. 12, n. 22) he says: “Indeed, the color of this body can be changed either by reason of health or by age, while the body itself has not yet perished. And this does not hold equally in all things, but in those things in which the things which are in subjects coexist, not so that the subjects themselves may exist. For in order that this wall be a wall, it is not made by this color which we see in it; since even if by some chance it should become black or white, or change some other color, nevertheless it would remain a wall and be called such.” And generally (On Eighty-Three Different Questions, q. 46): “For ideas are certain principal forms, or stable and unchangeable reasons of things, which themselves have not been formed, and by this fact are eternal and always having themselves in the same mode, which are contained in the divine intelligence”; and the essences of things are assimilated to and correspond to the divine ideas.
136. With these things lightly touched on concerning the word and nature of progress, it must indeed be conceded that human reason is perfectible, and therefore can progress. For 1) even prescinding from revelation, by which it can learn truths, in those very things which human reason investigates by natural means it progresses first, as it were negatively, namely by rejecting errors which were formerly mixed with truths already known. 2) Indeed, positive progress also must be admitted; for since we proceed from potency to act, and do not know all objects by intuition, but by the help of reasoning arrive gradually from known things at unknown things, it is impossible to see all truths immediately, and immediately to apprehend clearly and adequately those very truths which we do see. Hence St. Augustine, who in many places defends the immutability of truth, elsewhere excellently observes that the human mind, in relation to truth, can be in a different state. Thus, for example (On John, tract. 97, n. 1), he says: “Therefore those very things which concerning the eternity, truth, and holiness of God are said readily and openly without ceasing are understood well by some, badly by others, and by others are not understood. For he who understands badly does not understand. But by those very persons by whom they are well understood, they are seen by some less and by others better through the liveliness of the mind, and by no man are they grasped as by the angels.” 3) But what we say of one man considered according to the different times of his life can also be said of many men, or of societies of men, insofar as they exist in successive times. For the truths which were already known by some generation will greatly profit the succeeding generation in the inquiry of truth. Namely, those truths are handed down to it as a certain inheritance, which by continual study it can increase and amplify.
137. But, once these things have been conceded, the question is: 1) whether progress of this sort of human reason is necessarily continuous; 2) whether it ought to happen in the same way in religion as in other matters; 3) whether progress in religion happens in such a way that, revelation being excluded, we arrive at every religious truth by the help of reason alone. This indeed is asserted by the rationalists of Germany and the eclectics of France.
138. And so behold their system in a few words. They take as a principle that the character of human reason is such that, just as in arts and sciences, so also in the knowledge and practice of religion, it continually progresses. But they suppose that the primitive condition of the human race was ruder and almost barbarous, and therefore that religion itself, from the beginning very imperfect, in the course of centuries continually put on new forms, always more perfect, and perhaps still puts them on, until, as philosophy progresses, religion itself is carried forward to the highest degree of perfection. Therefore they think that, in the first age of the world, religion, mixed with many errors, inclined toward fetishism; but with the passage of time, once errors had been rejected, it became purer. They judge that this happened especially by the help of philosophers and other wise men who, endowed with sharper talent, both knew better themselves and, aroused by a certain special providence, taught others religious truths.
139. Therefore one and the same natural religion, under a different form and perfection, according to the different cultivation of human reason and state of development, was relatively true; just as any worship whatever offered to God was, in its own time, good, legitimate, and praiseworthy. Accordingly, with no distinction made, they establish that fetishism, anthropomorphism, polytheism, dualism, Buddhism, Mohammedanism, and finally Christianity are different phases of natural religion, each of which claims truth for itself for the time in which it flourished or flourishes.
140. We do not deny, they say, that certain more excellent forms or phases of religion have existed; and therefore the highest praises must be attributed, and the greatest thanks given, to certain distinguished men who, cultivating religion beyond the rest, have deserved very well of the human race. Among these Moses, Zoroaster, Solon, Numa, Confucius, Socrates, Christ, and Muhammad stand out. Indeed, if you except Draper, who was not ashamed to prefer Mohammedanism to Christianity, they generally concede that in the progress of religion Christianity claims the first place for itself, as appearing more closely conformed to the innate laws of reason. Nevertheless, wholly forgetting the divinity of Christianity, they so equate it with the other religions that they deny that it bears before itself the perfect form of religion. For first, they say, the Apostles, being slower in talent, did not always rightly grasp the doctrine of Christ. Then neither the Apostles nor Christ Himself entirely put off the traditions of the Jews and the fictions of the nations. Then finally Christ, as if by deliberate purpose, sometimes employed that method of teaching which is called accommodation. Yet this doctrine of accommodation, formerly common among rationalists, now most of them seem to have abandoned; for they prefer to consider Christ as one of the distinguished philosophers who, as he could, taught religious truths in his own time, yet, like the others, mixing many errors with them. I pass over those who have progressed so far that they deny the very real existence of Christ, judging that he represents only a mythical person.
141. Therefore the impious and equally absurd theory of the rationalists returns to this: that, every revelation being repudiated, they assert religion to be the work of reason alone; they ascribe its advancement and perfection solely to the successive development of reason; they acknowledge that form of religion which corresponds to the present cultivation of reason; and finally they accept Christianity understood and accommodated in this way. For otherwise, in their judgment, the Christian religion could no longer be approved by men who have already passed beyond the limits of adolescence.
142. Indeed all the authors of this impious system suppose the theory of relative and mutable truth, since they consider all religions, even those altogether opposed to one another, as relatively true and legitimate in their own age. But the French eclectics and the pantheists expressly assert that theory, and upon it as a foundation they build the mutability and progress of religion. According to these pseudo-philosophers, truth is reached by men not absolutely and as it is in itself, but only relatively and by a certain degree, as it were. For although objects are in themselves determined and fixed, nevertheless we attain only a little part of them, which corresponds more or less to absolute truth according to the general condition of progress of each age. Hence those things which are true, right, and holy at one time are found false and depraved in another age; and since this is true of truth generally, it must also be asserted by the same reason of religious truth. Compare, if you wish, the Dublin Review (“Mr. Mill’s Denial of Necessary Truth,” October 1871).
143. Therefore, with these things having been set forth: Section II. The proposed question is solved. PROP. VII. 1. Once divine revelation has been rejected, the human race cannot be recalled from ignorance of truths concerning natural law and religion by the help of philosophy or philosophers. Nor will the humanitarian progress fabricated by the rationalists help for this purpose: 2. if it is established as continuous, it contradicts history and experience; 3. if moreover it is transferred to religion, insofar as all religions are said to be diverse forms, successively more perfect, of one primitive religion, it is impious and absurd; 4. finally, if it is established under this title, that every truth is relative and mutable, it is not only absurd and impious, but also destroys the certainty of all human knowledge.
144. The first part is proved. I. In order that philosophers could teach religion to the human race, they themselves would first have to know with certainty the things which pertain to worship and morals. But the more excellent among the philosophers who were destitute of revelation or rejected it, as is plain from the preceding thesis, fell into the most disgraceful errors. Therefore. And indeed true religion cannot be except one (nn. 68 ff.); but philosophers could not teach one religion, since among them there was always the greatest disagreement. Certainly no school of philosophers held the entire truth; and even those schools which deserved best concerning moral discipline, such as the Academy, the Lyceum, and the Porch, went off into the most absurd opinions. Lactantius graphically sets forth the ignorance of the philosophers (Epitome of the Divine Institutes, c. 40): “There are innumerable sayings and deeds of the philosophers by which their foolishness can be refuted. And so, since we cannot enumerate all, a few will have sufficed. It is enough that it be understood that the philosophers are teachers neither of justice, which they did not know, nor of virtue, about which they lie. For what would they teach, who often confess their own ignorance? I pass over Socrates, whose saying is well known. Anaxagoras pronounces that all things are surrounded by darkness. Empedocles says that the paths of the senses for finding truth are narrow. Democritus testifies that truth lies sunk in some deep well; and because they find it nowhere, for this reason they affirm that no wise man has yet existed. Therefore, since there is no human wisdom, as Socrates says in Plato, let us then follow divine wisdom, and let us give thanks to God, who both revealed and handed it down to us, and let us congratulate ourselves that we hold truth and wisdom by a heavenly benefit, which philosophy, sought by so many talents and so many ages, could not find.” Nor would it have been easy for anyone to gather into a sum the truth scattered among individuals. “It is easy to teach,” says the same Lactantius (Divine Institutes, book 7), “that almost the whole truth was divided among the philosophers and sects… and that there was no sect so wandering, nor any philosopher so empty, that he did not see something from the truth. But while they rage with eagerness to contradict, while they defend even their own false things and overthrow even the true things of others, not only has the truth slipped away from them, which they pretended to seek, but they especially lost it by their own fault. But if someone had existed who gathered into one and reduced into a body the truth scattered among individuals and diffused through the sects, he certainly would not dissent from us. But no one can do this unless he is skilled and knowledgeable in the truth.”
145. II. But let us grant that the philosophers could have acquired for themselves the whole religious truth; nevertheless they could not themselves have expelled the ignorance of the human race. For by what way would they have taught the people? 1) By scientific instruction and philosophical investigation? But then all those difficulties would return which, as we have heard from St. Thomas (n. 126), make revelation necessary: for few are fit for philosophical investigation, few are zealous for it, and those themselves would attain truth only after a long time. Yet, as Lactantius has it (Divine Institutes, book 3, c. 16): “All philosophy must be cast aside, because wisdom is not to be studied, which lacks end and measure; but one must be wise, and indeed early. For a second life is not granted to us, so that when in this life we seek wisdom, in that one we may be wise; in this life each must be done. It must be found quickly, so that it can be undertaken quickly, lest anything perish from life, whose end is uncertain.” Hence Tully himself wrote: “Philosophy is content with few judges, deliberately fleeing the multitude, and is itself suspected and hated by that multitude; so that if someone wishes to reproach the whole of it, he can do so with the people favoring him.” 2) Would the philosophers have taught the people religious truths by the way of authority? But what is their authority? “Those precepts,” says Lactantius (Divine Institutes, book 3, c. 27), “have no weight, namely those proposed by the philosophers, because they are human and lack a greater authority, that is, divine authority. Therefore no one believes, because he who hears thinks himself to be as much a man as he who commands.” But did they not themselves take away every force from the very human authority of the philosophers, whatever it is, by their manner of living? For, as the same Lactantius observes (loc. cit., c. 16): “Those who only teach and do not do, themselves subtract weight from their own precepts. For who would obey, when the teachers themselves teach not to obey?” Behold what Tully writes concerning philosophers: “How often is any one of the philosophers found who is so formed in morals, so constituted in soul and life, as reason demands? who thinks his discipline not a display of knowledge, but a law of life? who obeys himself and submits to his own decrees? One may see others with such levity and boasting, that it would have been better for them not to have learned; others greedy for money, some for glory, many slaves of lusts, so that their speech wonderfully fights with their life; and this seems to me most disgraceful.”
146. III. Let us grant even that the philosophers did not lack a means of teaching the human race; still it is not thereby established that, without revelation, it could have learned religious truth. For for this purpose very many philosophers would be required, since a few would not suffice. They would have to be lovers of the human race and zealous for propagating religious truth; especially, men who had seriously applied their mind to investigating the laws of religion and morals; who would be prepared in soul to endure the troubles and labors necessary for rightly instructing the human race; who would furnish this even against the commands and threats of rulers, and would not adopt a system of accommodation. Who would expect these things from philosophers destitute of revelation? It is pleasing, therefore, to complete this argumentation with the confession of Rousseau himself, who writes (Emile, book 1): “I consulted the philosophers, I turned through their books, and weighed their various opinions. I recognized them all as full of spirits, affirming boldly, even in doubtful matters judging from the tripod, professing that they know everything, disentangling nothing, ridiculing one another. This indeed seemed to me common to all of them, in which they are least deceived. Elated and as if triumphant when they attack others; when they themselves are attacked, broken and cast down. If you examine their arguments, you find plainly none except those prepared for overthrowing something. If you count their votes, each bears the one which each attributes to himself. They cohere with one another in nothing except in contending; while they wish themselves alone to seem illuminated by the light of truth, candid, worthy of trust, then they command us in some way to acquiesce in their word and thrust upon us rotten and absurd fictions as true and certain principles.” See Hooke (On True Religion, on natural law, diss. 1, art. 1, prop. 2; it is also extant in Migne, complete course, vol. 2).
147. The second part is proved. I. As regards the arts and sciences, history places beyond every hazard of doubt a fact known to all, namely that in certain periods of times the human race not only did not increase the treasure of cognitions received from past generations, but rather diminished it; and therefore, instead of having advanced or made progress, it rather followed the way of regress. It escapes no one, for example, that Greece attained the perfection of the arts under Pericles, of eloquence under Demosthenes, of moral philosophy under Socrates, of metaphysics, physics, and other natural sciences under Plato and Aristotle, and of military glory under Alexander. But who is ignorant that this glory, in subsequent times, turned toward setting? Almost the same thing happens in Latium. In the space of one century there flourished Tully, Sallust, Titus Livy, Tacitus, Virgil, Horace, etc., who carried eloquence, history, and poetry to the summit of perfection; but afterward, together with the Empire, Latin letters, continually declining, almost perished. The records of all nations which exist teach their rise, increase, summit, and then the decrease and destruction which followed, as regards arts and sciences. That is, societies of men seem in this matter to imitate what we see with our eyes in the organic nature of individuals: they are born, grow, and are dissolved.
148. II. But as regards religion: 1) history likewise is witness that in the beginnings of the human race religion and morality existed perfect; that men worshipped one God; that only in later times were peoples led into polytheism and substituted for the legitimate worship of the true God the foul adoration of idols. Worthy to be consulted on this matter is Thebaud, S.J. (Gentilism: Religion Previous to Christianity, New York, 1876). Indeed, all know that precisely at the time when polytheism was dominant among the nations, the Jewish nation professed monotheism; just as monotheism is now found not only in the Christian people, but also among Persians, Indians, Chinese, etc. And so is the passage from monotheism to polytheism called progress? Then the nations which now are monotheist have regressed. Is it called regress? Then those which formerly passed from monotheism to polytheism regressed. On either hypothesis the theory concerning religion continually progressing is shown false. 2) But our very experience manifests to us the departure of nations from the true religion, just as of men, when, legitimate authority being rejected, from Catholics they have become heretics, from heretics theists, from theists pure rationalists, and finally atheists. Who is ignorant that this was the process, for example, of the philosophism which prevailed in the last century? Certainly those who now, having followed the new philosophy, under the name of progress profess naturalism and rationalism have progressed so far that they embrace materialism or pantheism. Therefore let those hold the law of continual progress, or of reason and religion continually progressing, who do not fear to call a return to materialism and pantheism progress; for these are most ancient errors. 3) History so openly contradicts the asserted law of continual progress that finally even its defenders acknowledge this contradiction. But they try to explain it by calling the regressions manifest in history anomalies, and indeed such as contribute by some hidden reason to the progress of humanity. They speak almost in the way in which rivers not rarely hide their waters under the earth, so that, after new waters have been gathered there, they may be increased and appear more abundant. But everyone sees that an evasion of this sort is the work of imagination; for, to pass over the other points, no one will say that ignorance contributes to increasing knowledge, or that errors of themselves contribute to increasing truth.
149. III. If we wish to penetrate the inner reason which impedes the continual progress of the human race, we must cast our eyes upon those things which happen to the individual man. Indeed, various causes, whether voluntary or involuntary, impede the continuous progress of any man in such a way that, instead of acquiring new cognitions, he rather forgets those which he once knew. Therefore what can happen to individuals can also happen to nations, and, with proportion, from the same causes. But in the business of religion it is still easier to regress, or at least not to progress; for religious truths are opposed to the passions of our corrupt nature. Material progress itself can sometimes hinder religious progress; for the more we are turned toward earthly things, the more we can be turned away from eternal things, so that the material man does not perceive those things which are of the spirit.
150. St. Thomas had already wonderfully solved this question (Ethics, book 1, lect. 11), where he says: “It belongs to the nature of man to use reason for the investigation of truth. But it is proper to reason not to apprehend truth immediately. And therefore it belongs to man to advance gradually in the knowledge of truth. But separated substances, which are called intellectual, have knowledge of truth immediately, without inquiry… In the case of things which are well disposed toward something being circumscribed, time seems to be, as it were, a discoverer or good cooperator, not indeed because time of itself does anything for this, but according to those things which are done in time.” “Time seems to be, as it were, a discoverer or a good cooperator, not indeed because time of itself operates anything for this, but according to those things which are done in time. For if someone, as time proceeds, gives effort to investigating truth, he is aided by time toward finding truth, both as regards one and the same man, who later will see what he had not seen before, and also as regards different men, as when someone looks upon those things which were discovered by predecessors and adds something. And in this way additions have been made in the arts; from the beginning some small thing was discovered, and afterward through different persons it gradually advanced into a great quantity, because it belongs to each person to add what is lacking in the consideration of predecessors. But if, on the contrary, the exercise of study is omitted, time is rather a cause of forgetfulness, as is said in the fourth book of the Physics, both as regards one man, who, if he gives himself to negligence, will forget what he knew, and as regards different men. Hence we see that many sciences which flourished among the ancients, studies gradually ceasing, have passed into oblivion.”
151. The third part is proved. I. If all religions which exist or have existed in the world, according to the law of continual progress, were nothing but diverse forms, successively more perfect, of one and the same religion, it would follow that all, for their various ages, were equally true. But this is absurd, since they are opposed to one another contradictorily or even contrarily; but contradictories and contraries cannot be true at the same time. Cicero himself recognized this truth; for after he had set forth various opinions about the gods (On the Nature of the Gods, book 1, n. 2), he adds: “There is no matter about which not only the unlearned but even the learned disagree so greatly. Since their opinions are so varied and so disagreeing among themselves, one of two things certainly can happen, that none of them is true; the other certainly cannot happen, that more than one is true.” Wherefore all the arguments by which we proved Proposition III must here be recalled.
152. II. The system which we are attacking assumes as certain that religion is the work of reason alone, and that there is no revelation. But this is repugnant both to history and to reason. 1) It is repugnant to history. For authentic and historically most certain monuments, such as the books of Moses, prescinding for the time being from their divinity, testify that at the beginning of things God communicated true and perfect religion, monotheism, to men through revelation. But, as we said, with the lapse of time the greatest part of men deserted the true religion and substituted for the worship of the true God the vain and impious worship of many gods. With these monuments, which make us certain that true religion existed in the beginning by the help of revelation, even the traditions themselves of the gentiles agree, which, although in a confused and obscure way, testify to some special communication of God for teaching men. 2) It is repugnant to reason. For reason, as we proved above, evidently manifests that revelation is possible, indeed necessary as regards religion, even if we remain within the limits of nature; and that the chief men even among the philosophers, destitute of revelation, erred disgracefully concerning matters of worship and morals. Therefore it is repugnant to reason to exclude any revelation as if a priori, and to attribute progress solely to the powers of reason.
153. III. Whoever seeks the intrinsic principle of the error which we attack will find it in the absurd system of pantheism, which could also be proved historically. According to the pantheists, only one substance exists, which unceasingly and continuously evolves and unfolds itself, like a spider which, as it were, unfolds and draws out its web from its own entrails. Thus humanity, like the rest of things, is nothing but a certain manifestation and evolution of that substance. But since religion itself is nothing but, as it were, a consequence of human nature, just as humanity evolves perpetually, so religion itself evolves perpetually. It is enough to have indicated these things, so that anyone considering them can gather for himself that the system which we are here attacking ultimately teems with those absurdities with which pantheism itself teems.
154. The fourth part is proved. I. “The truth of knowledge,” says St. Thomas (Contra Gentiles, book 1, c. 59), “is the adequation of intellect and thing, according as the intellect says that what is, is, or that what is not, is not.” Hence, in order that truth of knowledge be present, “that which the intellect says and knows in understanding must be made equal to the thing, namely, so that it is in the thing as the intellect says.” Therefore, if there are objects which immutably and necessarily are what they are, there is immutable and necessary truth; and therefore it cannot be said that every truth is relative and mutable. For the concept which the intellect forms about objects either corresponds to them and presents them as they really are, or it does not correspond, referring them otherwise than they are. If the first, certainly the truth of knowledge is immutable, just as the essences themselves of things are immutable. But in the other hypothesis no truth is present, neither perfect nor imperfect or vitiated. Likewise, enunciable propositions either contain immutable truth or falsity, according as the thing has itself as it is enunciated, or otherwise. For when I say, for example, “man is endowed with liberty,” the judgment which I put forward is immutably true; but the contrary judgment, “man is subject to necessity,” is false. Nor can we find degrees in indivisible truth, is or is not, so that a false judgment has some degree of truth. In order that we may in some way clarify this argument, let us observe that there certainly are objects which immutably are what they are. For 1) the essences of things are immutable in this sense, that some thing, so long as it is, necessarily has all those things through which it is such a thing and not another; just as human nature necessarily and immutably has all the constituents of human nature, and if you take away soul or body, by that very fact you no longer conceive man. 2) The same must be said about the relations which necessarily flow from the essences of things; for they too are in themselves immutable and necessary. Certainly it will always be true, for example, that human nature necessarily excels the nature of brute animals, and that it is dependent on God. 3) Singular things are subject to continual changes, and therefore true cognitions about them are in some way mutable. Namely, it can happen that at one time something must be affirmed of them which, since they change, must be denied at another time. Nevertheless, as St. Thomas noted (I, q. 84, a. 1): “Of mutable things there are immobile relations; thus Socrates, even if he does not always sit, nevertheless it is immovably true that when he sits he remains in one place. And for this reason nothing prevents there being knowledge about movable things… There can also be some knowledge of generable and corruptible things, for example natural knowledge, not according to the particulars which are subject to generation and corruption, but according to universal reasons, which are of necessity and always.”
155. II. If someone asks the reason why the essences of things are necessary and immutable, and therefore why true knowledge of them must be absolute and immutable, what is handed down in metaphysics must be recalled. Namely, the essences of things must correspond to the ideas of the divine intellect; these ideas God has by contemplating His own essence as imitable ad extra. Compare what we set forth in the treatise On God the Creator (n. 128 ff.). Therefore mutability cannot be admitted in the essences of things unless mutability is admitted in the divine intellect and in the divine essence itself; and these things are openly repugnant.
156. Hence one understands: 1) the argumentation by which St. Thomas (I, q. 16, a. 1) proves that the divine intellect, and not our intellect, is the measure of truth. “Since the true,” he says, “is in the intellect according as it is conformed to the thing understood, it is necessary that the notion of the true be derived from the intellect to the thing understood, so that the thing understood also is called true according as it has some order to the intellect. But the thing understood can have order to some intellect either per se or accidentally. Per se indeed it has order to the intellect on which it depends… Natural things are said to be true according as they attain the likeness of the species which are in the divine mind.” And St. Anselm (Dialogue on Truth, c. 7): “Teacher: Do you think that there is ever anything, or anywhere, which is not in the highest truth, and which has not received from there what it is insofar as it is; or which can be other than what it is there? Student: It is not to be thought. Teacher: Whatever therefore truly is, insofar as it is this, is what it is there. Student: You can conclude absolutely that everything which is, truly is, since it is not other than it is there. Teacher: Therefore there is truth in the essence of all things which are, because they are this which they are in the highest truth.” One understands: 2) that only those teach the mutability of truth who constitute our intellect as its measure. Thus Protagoras, who (Laertius, book 9, segment 311) held that “man is the measure of every truth,” consequently denied the absolute true, as Cicero reports (Academics, book 2, c. 46): “Another judgment is that of Protagoras, who thinks that what seems true to each person is true for each person.” But since the notion of God is absolute and immutable, he consequently held that it is hidden from us whether God exists (compare On the Nature of the Gods, book 1, n. 23). Hence St. Thomas (I, q. 16, a. 1, ad 2) writes: “It must be said that the ancient philosophers did not say that the species of natural things proceed from some intellect, but that they come from chance. And because they considered that the true imports a comparison to intellect, they were compelled to establish the truth of things in order to our intellect.” And the more recent assertors of relative truth are chiefly those who, according to pantheistic principles, affirm that our mind, by knowing things, creates those same things!
157. III. The absurd theory concerning mutable truth can be refuted from false consequences. For 1) it leads to absolute skepticism. For if we attain no object as it is in itself, if we do not know the relations of things as they really have themselves, all our notions are mutable, so that the things which we now think true may rightly be found false in the course of time. Therefore we act prudently if we now hold nothing as certain, but doubt about all things. And certainly sad experience confirms the inference at which we arrive by reasoning from the adversaries’ principles. For general skepticism occupies the mind of all those who have too greatly extolled the rights of reason; and they doubt about the chief religious truths, about the existence of a personal God, about the immortality of the human soul, indeed about the very first principles, such as the principle of contradiction. 2) Indeed it leads to nihilism. St. Augustine had already noted this, writing (Soliloquies, book 2, c. 5, n. 8): “A. The true is that which has itself as it seems to the knower, if he wills and is able to know. R. Therefore that will not be true which no one can know. Then if the false is what seems otherwise than it is, what if this stone seems to one person a stone and to another wood? Will the same thing be both false and true?” And (n. 7): “But if you say that nothing is true, do you not fear lest it follow that nothing exists through itself? For from the same source from which this is wood, from there also it is true wood. Nor can it happen that through itself, that is, without a knower, it is wood and is not true wood.”