Commentaria in Summam contra Gentiles, Liber III

After St. Thomas showed that we cannot understand separate substances in the way the aforesaid philosophers posited, he now wishes to show that human happiness does not consist in the knowledge of separate substances of this kind¹.

I. And he argues first in this way: To understand separate substances is impossible for man according to the aforesaid positions, as is clear from what has been said. Therefore, human happiness is not constituted in such a knowledge of them. — The consequence is proved: Because then man would exist in vain; and his natural desire for happiness, which is the end of man, would be futile.

Note that, since that is said to be in vain, as is clear from Aristotle, II Phys.², which does not attain the end for which it exists, St. Thomas takes from this that something comes to be in vain which is for some end that it cannot reach: for in this way it is evident that such a thing never attains its end. Therefore, if man is ordered to knowing separate substances as to an end, and it is impossible for him to know them, it follows, as St. Thomas deduces, that he was made in vain. By a similar reasoning it follows that his natural desire is futile and in vain: namely, because it will never be fulfilled.

It must be noted, however, that although it is not contradictory for something to be the end of a nature, and yet for nature to be impeded in certain particulars from attaining that end, as we see in the works of nature; nevertheless, it is contradictory for something to be the end of a nature and for it to be impossible for nature to reach it: because nature does not incline nor move toward the impossible, as is stated in II De Caelo, text 51³. Therefore St. Thomas first proposes that the happiness of man, which is his end, cannot be placed in that which man cannot reach; then he proves it, because, if it were admitted that this is the end and happiness, then man would exist in vain. Which no wise man would say concerning any whole nature: although concerning some individual of a nature it is not unfitting that it be in vain with respect to some end, namely, when it does not reach some end intended by nature.

II. Secondly: In order for the agent intellect to be joined to anyone, it is necessary that he understand in act through the speculative intellect all the natures of sensible things, and all their powers, operations, and motions. But it is impossible for anyone to know this through the principles of the sciences, through which, as they say, we are moved to that continuation itself. Therefore it is impossible for man to arrive at that continuation in the manner assigned by them. Therefore, etc. — The major is proved: Because both according to Alexander and according to Averroes, in order for the agent intellect to be united to us as a form, it is required that all speculative objects of the intellect be actualized in us in act. But all the species of sensible things are understood in potency. — The minor is also proved: Because from those things which are subject to our senses, from which the aforesaid principles are taken, one cannot arrive at knowing all the aforesaid things.

Concerning what is said, that no one can understand the natures of all sensible things, and all their powers, operations, and motions, it should be considered that this does not assert an impossibility simpliciter, which, I say, is an impossibility through an implication of contradiction; for, when I say, Man knows all things of this sort, the predicate is not repugnant to the subject; but it asserts an impossibility which is from a defect or weakness of power, just as we say that a sick man cannot walk. For thus, because the first principles from which science originates in us are weak in us, and do not extend except to those things which are subject to the senses, or to which we are guided by sensible things of this sort, we are unable through principles of this sort to know all the aforesaid things. For what is subject to the senses of one man is not able to lead us into the knowledge of all sensible things, neither by reason of likeness nor by reason of causality: for there are many, and almost infinite things of which one is neither similar to the other, nor in any way its effect or cause.

III. Thirdly: Even granted the possibility of this kind of continuation of man to the agent intellect, it is clear that such perfection comes to very few men, and not even to the philosophers themselves. Whence they all assert that very many things are unknown to them: as is clear concerning Aristotle regarding the squaring of the circle, and regarding those things which pertain to the celestial bodies. Therefore, etc. — The consequence is proved: Because happiness, as is stated in I Ethics, is a certain common good which many can reach, unless they are maimed, that is, unless they lack some principle necessary for acquiring virtue; just as happens to madmen, in whom there is a defect of reason on account of some indisposition of the sensitive powers. This is also true of every natural end of any species.

Concerning the proof of the consequence, it must be noted that that assumption is true of natural happiness, which everyone can reach by the power of his nature. Whence St. Thomas also added that that is true of every natural end. For, since nature fails in the fewer cases, the things that belong to one species for the most part have principles sufficient for the acquisition of the end of their species; and, while they are moved toward it, they finally attain it. Therefore, since it does not happen to many, indeed perhaps to none of those who devote themselves to study and the acquisition of the sciences, that they arrive at that perfect continuation with the agent intellect through their study, it manifestly remains that the natural happiness of man, or his ultimate natural end, does not consist in the aforesaid continuation.

IV. Fourthly: Aristotle, in I Ethics, proves that the happiness of man is his operation according to perfect virtue. In Book X, however, he shows that it is in speculation; and, as is held from him in the same place, it consists in the act of wisdom. But wisdom, according to him in VI Eth. and I Metaph., is one of the speculative sciences, and is the head of the other sciences. Therefore the opinion of Aristotle, whose view the aforesaid attempt to follow, was that the ultimate happiness of man which man can acquire in this life is the knowledge of divine things such as can be had through the speculative sciences. Therefore it does not consist, according to him, in such a continuation: rather, this mode of knowing divine things after the attainment of the speculative sciences was fabricated by his commentators, namely Alexander and Averroes.

2. Concerning the opinion of Aristotle a doubt immediately arises. For it is evident that there are few, in comparison to the whole multitude of men, who arrive at that knowledge of divine things which is had through the speculative sciences. But it belongs to the notion of happiness, according to Aristotle himself, that many arrive at it, and fewer fall short of it. Therefore human happiness does not consist in such knowledge. And thus from his own statement the opposite of his position follows.

He answers that it does not belong to the notion of happiness of this life, according to Aristotle, that the greater part of men arrive at it; but that it can be reached by one's own power, and that, if one is moved toward it, one attains it by one's own motion; because there are few men who are maimed, and lack natural principles for acquiring virtue⁴. And thus also there are few who devote themselves to study and the acquisition of speculative sciences who do not attain that knowledge of divine things in which human happiness consists. Whence the opposite of his position does not follow from his own statement.

3. But if it is urged, from the words of St. Thomas here⁵ and in the preceding⁶, that the things which belong to a species attain the natural end of that species for the most part; and thus it does not suffice that they are able to attain it, and that, while they are moved toward it, they attain it: — it is said, as was also replied above⁷, that indeed the greater part of those things which are contained under a species attains the natural end of that species; nevertheless it is not necessary that this happen in every state of that nature, but it suffices that it occur in some state. In this way, however, it is true that the natural end of man is the knowledge of divine things, which man can naturally reach; and that the greater part of men will arrive at it, or perhaps all, not indeed in this life, but after death; although the mode by which man will then understand divine things we do not have from Aristotle. Whence Aristotle himself also posited that man does not attain perfect happiness in this life, but in his own way⁸: as if he wished to say that at some time, after this life, he will attain perfect beatitude, which is absolutely the end of human nature; in this life, however, man can indeed attain imperfect beatitude. But there are also few who arrive at it: because there are few who exercise themselves in the speculative sciences, on account of the impediments of this life, concerning which it was spoken in the preceding⁹. Whence the knowledge of divine things acquired in this life through the speculative sciences is not simpliciter the end of human nature: but it is its end for this mortal state, in which there are many things impeding and drawing back from the attainment of such an end.