Commentaria in Summam contra Gentiles, Liber I

After Saint Thomas has shown that there is a twofold truth concerning God, he now declares the manner of manifestation of each truth ¹. In regard to this he does two things: first, he determines absolutely the manner of manifestation of this kind of truth; second, comparatively, in chapter VII. — In regard to the first he does two things: first, he determines the manner of such manifestation insofar as it lies on the part of the teacher; second, insofar as it lies on the part of the learner, in chapter VI. — In regard to the first he does two things: first, he treats of the manner of those things that can be known of God naturally; second, of the manner of those things that exceed natural reason ².

I. As to the first point, lest it perhaps seem to anyone, as he says, that since such truth can be attained by reason, it was handed over in vain to be believed by supernatural inspiration, he sets down this conclusion: The truth of divine things, which can be accessible to the inquiry of reason, is fittingly proposed by God for man to believe. It is proved from the inconveniences that would follow if this were not so. The first is that knowledge of God would belong to only a few men. For most are deterred from the inquiry into truth for three reasons. Namely, either on account of the constitution of the body, from which many are naturally indisposed toward science and cannot attain the highest degree of human cognition, which consists in knowing God; or on account of the necessities of domestic affairs, because of which many cannot devote themselves to the leisure of contemplative inquiry; or on account of sloth, from which most flee the labor of acquiring learning: for in order to have the knowledge of God that can be had naturally, one must know many things beforehand, since nearly all of philosophy is ordered to it, for which reason metaphysics remains to be studied last; wherefore, although God has implanted in the minds of men a natural desire for knowing, there are nevertheless many who refuse to undergo the labor of learning.

II. It must first be noted here, from the doctrine of Saint Thomas in the Third Book, d. xxv, q. II, a. 2 ³, that the quantity of knowledge can be considered in two ways: namely, according to its objects, and according to the efficacy of the act with respect to the object. Therefore what he says—that the highest degree of human knowledge is to know God—must be understood as regards the object, not as regards the efficacy of the act.

It must be noted, secondly ⁴, as St. Thomas has it on Boethius, De Trinitate, q. 5, a. 1, ad 9 ⁵, that metaphysics is indeed prior to the other sciences by nature, that is, according to perfection; yet with respect to us it is posterior to the other sciences. For this reason Avicenna, in the first book of his Metaphysics ⁶, says that the order of this science is such that it is learned after the other sciences, which St. Thomas also says in this place. But although this is so concerning the science itself, insofar as the properties of being and of separate substances are investigated in it by demonstration, nevertheless certain metaphysical terms must be known with respect to us before the terms of the other sciences, according to their concepts, since the terms of the other sciences are resolved into them. For this reason, although those terms are called metaphysical, insofar as the properties of the things they signify are investigated in metaphysics, they are nevertheless, as regards their concepts, common to all the sciences. — If it is said: Why, then, in Metaphysics V ⁷ are their rationes determined? — it is answered that this is because, if a treatise is to be set forth concerning all of them together, it pertains more to the metaphysician than to any other craftsman, since he also inquires into their properties. Yet it is not thereby denied that they are terms common to all the sciences. But the difference lies in this: metaphysics determines them as subjects, or as parts or passions of subjects; the other sciences, however, use them as antecedents to their subjects, and as known through the way of sense.

It must be noted, thirdly, that Saint Thomas did not say absolutely that the whole of philosophy is ordered to metaphysics, but added almost: because, as he himself says in Trin. q. v, a. 1, ad 9 ⁸, there are certain sciences that are not necessary absolutely for metaphysics, but only for its well-being, such as music and the moral sciences and the like.

Note fourth, that natural appetite, as treated in Iª, q. LX, a. 1, can be taken in two ways: in one way, as distinguished from appetite that follows cognition; in another way, as distinguished from free appetite. In the first way it names only the order of nature toward something, and it imports nothing other than the form of a thing with its natural habitude toward something, just as the appetite of a heavy body for the place below is nothing other than the form of gravity with its habitude toward the place below: and it stands as a first act. In this way every power naturally appetites what is fitting to it, as is said in Iª, q. LXXVIII, a. 1, ad 3. In the second way it names an elicited act following cognition, yet so determined to one of two opposites that it cannot be bent toward the other: just as all naturally appetite beatitude by an act elicited by the will following the apprehension of beatitude. — Therefore the appetite for knowing, which Saint Thomas says, and Aristotle as well, is natural, ⁹, although it can be taken in the first way, because the intellect by its nature has a habitude and order toward cognition as toward what is fitting to it; yet because this does not belong to the intellect alone, but to every power, as we have said, in being borne toward what is fitting to it; and Saint Thomas and the Philosopher seem to wish to posit something particular about the appetite for cognition that is not found in the appetite for the operations of other powers: therefore this appetite must be said to be a certain natural act of the will by which the will is borne toward the cognition proposed to it in such a way that it cannot be borne toward the opposite. This also seems to be what Saint Thomas wishes in Iª IIªe, q. x, a. 1; and IIª IIªe, q. CLXVI, a. 2, when he posits the virtue of studiousness as the moderator of this natural desire.

III. It is absurd, because men would scarcely arrive at that knowledge except after a long span of time. First, on account of the depth of the knowledge, for which the human intellect is found suitable only after long practice. Second, on account of the many things that are presupposed. Third, on account of the movements of the passions, which abound in youth and by which the soul is rendered unfit for the knowledge of so great a truth.

It must first be noted that, since abstract things, considered apart from matter, cannot be known by us except from sensible things, in order that our intellect—to which sensible things are natural—may be raised so far as to draw out from the forms of sensibles a knowledge of such substances, it is necessary beforehand that it be exercised in the operations of the intellect, abstracting universals from particulars and common features from proper ones, so that through such exercise of abstraction it may become more apt for the knowledge of immaterial things. For the intellect cannot attain its noblest operations unless, through assiduity and exercise in lesser ones, it becomes more vigorous and more prompt for investigating hidden things. Much less, therefore, can it be raised to that substance which is most immaterial and most remote from the senses, unless it has been strengthened after long exercise. Hence Saint Thomas says that our intellect cannot pluck that depth of knowledge except after long exercise. For there is caused in the intellect, by study and exercise, a certain aptitude for investigating difficult matters, which would not be present without such exercise. Similarly, the interior sensitive powers, which the intellect employs, are rendered more apt by such exercise, each in its own order, for inquiring into the truth of subtle things.

It must be noted, secondly, that since intellectual cognition comes about through abstraction from sensible things, while on account of the vehemence of the passions the intention of the soul is drawn away from intelligibles toward sensibles: by reason of the vehemence of the passions the act of contemplation is hindered to the greatest degree. Therefore the moral virtues, especially chastity, as Saint Thomas says (II-II, q. 15, a. 3), dispose a man most of all toward perfection in intellectual operation. Where, then, a multitude of passions arises, as happens for the most part in the young, there the soul is not apt for subtle speculations; but in resting and sitting still from the tumults of the passions, as the Philosopher says, one becomes prudent.

IV. The third inconvenience is that knowledge of God would be had with doubt and admixture of error. For the weakness of reason, together with the mingling of phantasms, makes it happen that even those things most truly demonstrated remain doubtful in the eyes of many, since they do not grasp the force of the demonstration—especially when they see that those who are called wise teach different things. It also happens that among the many truths that are demonstrated, many falsehoods are mixed in, which are asserted by some sophistical or merely probable argument that is taken for a demonstration. Therefore it was necessary that what is to be held concerning God be determined for us through faith.

It is concluded, therefore, that divine mercy wisely provided that it should command those things also which reason can investigate to be held by faith, so that all might become partakers of divine knowledge easily, and consequently quickly, and without doubt or error.

It should be noted first that this weakness of the intellect does not signify an illness or something adventitious beyond nature in our intellect, but rather its natural order among intelligible things. For since it holds the lowest place in such a genus, and is a most imperfect thing—just as prime matter is in the genus of material things—it therefore has by its own nature that it be feeble in grasping truth and easily deceived.

It should be noted, second, that although phantasms serve our intellect for understanding, the admixture of phantasms nevertheless impedes the knowledge of truth concerning immaterial things in many. For since they are likenesses only of material things determined to here and now, some who understand through such phantasms cannot understand that anything exists in the nature of things which is not material and determined to some definite place; on account of which they fall into many errors about immaterial things. Therefore, the very admixture of phantasms in our intellection, although necessary for us in order to understand, is yet a weak and disproportionate instrument with respect to immaterial things, and for this reason it is frequently the cause of error in investigating the truth of such immaterial realities.

The first conclusion is confirmed by the authority of the Apostle, Ephesians 4: "You must no longer walk" etc. It is confirmed secondly by the authority of Isaiah 54: "I will make all your children taught by the Lord", etc.

V. But concerning what was said in the first difficulty, a twofold doubt arises. The first¹⁰ concerns the claim that metaphysics is to be learned last of all. Against this it is argued as follows. First: Metaphysics proves the principles of the other sciences, as Saint Thomas says, Trin. q. v, a. 1, ad 9¹¹. Therefore it ought to precede the other sciences. – The consequence is evident, because every science depends upon knowledge of its principles.

Second. Metaphysics supplies principles to all the sciences: as is the mind of St. Thomas in many places, especially Trin., q. 5, a. 1, ad 3¹². Therefore etc. – The consequence is proved. Because those things that pertain to metaphysics cannot be known except through metaphysics. If, then, the other sciences use principles that are proper to metaphysics, therefore metaphysics must be included in all the sciences as prior to them. And consequently it must be learned first.

Third. We must always proceed from what is better known to us, as the Philosopher shows in I Posterior Analytics¹³. But the principles that are proper to metaphysics are better known to us than all those handed down in the sciences. Therefore our knowledge must begin from them. Therefore metaphysics is to be learned first.

VI. The second doubt¹⁴ concerns the point that most people are deterred from the inquiry into truth by toil and sadness. For it is argued against this. The inclination of nature is no less than a habit. But a habit produces ease and delight in its proper acts, as is said in II Ethic.¹⁵ Therefore so does nature. If, then, men are inclined by nature toward science and knowledge, the acquisition of science will be easy and delightful. Therefore no one is deterred from it by sloth or toil.

VII. To make the first doubt evident¹⁶, it must first be considered that the first principles and universals of all the sciences can be considered in two ways: in one way, with respect to their truth absolutely; in another way, with respect to the judgment made about them and their defense against those who attack them. In the first way they belong to a single habit per se, which is called intellectus, which Aristotle, in Book VI of the Ethics¹⁷, divides against science and wisdom. In the second way, however, they belong to the metaphysician, as Saint Thomas says, Iª IIae, q. LXVI, a. 5, ad 4: for the metaphysician disputes against those who deny such common principles, because they are constituted from common terms, which fall under the consideration of the metaphysician¹⁸.

It must be considered, second, that although these principles belong to the intellect which is the habit of the principles, according to their truth considered absolutely, and to metaphysics with respect to their examination and defense, they are nevertheless common to all the sciences, insofar as their terms are extended to the terms of the other sciences, and insofar as science has a dependence upon the intellect which is the habit of these principles, as is the mind of Saint Thomas, Iª IIae, q. 57, a. 2, ad 2. Hence it may be said that these principles, as absolutely true, all sciences take from the intellect which is their habit; but as already examined and defended against those who attack them, they take them from metaphysics. Therefore XI Metaph., lect. 1, Saint Thomas says that one science—and he means metaphysics—considers these principles, to which belongs the consideration of the common terms, and from it the other sciences take principles of this kind.

It must be considered, third, as can be gathered from the doctrine of Saint Thomas super Boet. Trin., q. VI, a. 1¹⁹, that we can speak of the sciences in two ways: in one way, with respect to their ordered acquisition; in another way, insofar as they have already been acquired and discovered.

VIII. It is said, therefore, first, that with respect to their acquisition through the discovery of human reason, metaphysics is last: because all the other speculative sciences are ordered to it, and their discovery presupposes the discovery of metaphysics. And according to this reasoning, nothing belonging to metaphysics, as metaphysical, needs to be understood beforehand; but well indeed is the knowledge of the first principles known by the habit which is intellect, and this precedes the discovery of any science whatever, since no science has perfectly the character of a science except insofar as it depends upon such a habit.

It is said second, that if we speak of the sciences as they have already been discovered, then it is not unfitting that other sciences use metaphysical principles as already examined and defended against their attackers by metaphysics.

It is said third, that metaphysics need not on this account be learned before the other sciences. First, because the metaphysical habit is concerned first and principally with being and the passions of being, and also with separate substances; but not with principles of this kind, since they are not conclusions demonstrated in metaphysics. – Second, because the other sciences receive those principles on loan from metaphysics; and therefore it is not necessary that this habit be possessed beforehand, but it suffices that it be discovered and acquired at some time, even after the other sciences. Hence the other sciences believe these principles of metaphysics, namely, that they have been examined and defended by it, although they see them as having their dependence from the intellect of those very principles.

IX. To the first argument, however, the opposite is said: that metaphysics is not said to prove the principles of the other sciences in such a way that they are known demonstratively through the habit of metaphysics, just as a subalternating science is said to prove the principles of a subalternated science; but because through these common principles, according to some consideration pertaining to metaphysics, the principles of the other sciences are made manifest, while all sciences depend on the habit of those principles, which is called intellectus; and while they are resolved into those principles, naturally known but borrowed by the metaphysician according to some consideration, namely insofar as they are principles proper to no single science but common to all, although they are considered more principally by the metaphysician.

To the second it is said that metaphysics does not furnish its principles to the other sciences while it is considered in them according to the order of discovery and acquisition, as was said²⁰; but it furnishes them insofar as all the sciences, once discovered, are understood, inasmuch as all the sciences now receive from metaphysics those principles mutually, as confirmed and defended by it, although they are naturally known in themselves. Hence it does not follow that metaphysics must be learned before the other sciences.

To the third it is said first, that the first principles according to their absolute truth are known to us prior to all the sciences. But with respect to their examination and defense against those who attack them, they are known later. – It is said second, that because according to their truth they belong to the intellect which is their habit, but according to their examination and defense they belong to metaphysics, it does not follow that metaphysics precedes the other sciences, but only the intellect which is their habit, implanted in us by the natural light of the agent intellect.

X. To the second doubt²¹ it is said first that not every inclination of nature is like the inclination of a habit. For, as St. Thomas holds, Truth q. XXIV, a. 10, ad 1, natural inclination toward something is twofold: in one way, when it has within itself a sufficient principle from which that thing follows of necessity; in another way, when it does not have within itself a sufficient principle from which that thing would follow necessarily—as it is natural for a woman to conceive a child, and for free choice to tend toward the good. The first kind of natural inclination therefore produces ease and delight in operation in those who possess cognition, and it resembles the inclination of a habit. But with the second there remains difficulty and labor in acquiring that toward which the inclination is natural, and on account of the labor someone can be deterred from its acquisition. And thus it happens in appetite as in science.

It is said second, that although a habit of itself produces facility in operation, nevertheless, on account of some impediment arriving from without, as is said in I-II, q. 65, a. 3, ad 2, one who has a habit suffers difficulty in operating, and consequently feels no delight. So likewise a man can be withheld from the acquisition of knowledge, even though he has a natural inclination to it, by the labor of learning and other causes, as Saint Thomas says, Metaphysics I ²² For, as he himself also says in Metaphysics V, the chapter on the Necessary ²³, the impulse of natural inclination can be impeded in the pursuit of what has already been begun, and prevented from beginning its motion.

On the contrary, natural desire is not altogether in vain: because nature does nothing in vain, as is said in II On the Heavens ²⁴ Therefore, given that a man may for a time be hindered from the acquisition of knowledge, nevertheless at some point his desire will be fulfilled and the hindrances will cease.

It is answered that, although the natural desire consequent upon the whole of nature cannot be entirely frustrated without being fulfilled in some individual, it is nevertheless not unfitting for it to be frustrated in certain individuals: especially when such a desire is an elicited act of the will; and most of all if there is not in reality a completed principle from which that to which the natural inclination is directed must necessarily follow; just as it is not unfitting for a woman to remain perpetually without offspring, although she is naturally inclined to it.

It could also be said that this natural desire will be fulfilled in the soul separated from the body: as Porphyry said, it will then be blessed, even though, while joined to the body, it does not attain beatitude ²⁵.