Commentaria in Summam contra Gentiles, Liber III

As to the third point ¹, St. Thomas shows that the natural desire of separate substances does not come to rest in that knowledge of God which they possess through their own essences.

I. And he argues first as follows. The aforesaid knowledge of God is an imperfect species of knowledge: because we do not consider that we know something if we do not know its substance; and the principal thing in the knowledge of a thing is to know what it is, namely by comparing one particular knowledge of a thing to another. Therefore, etc. — The consequence is proved. Because everything that is imperfect in some species desires to attain the perfection of that species: as is clear in the case of one holding an opinion about something, who desires to have scientific knowledge about it.

Secondly. Separate substances know that God is the cause of all things whose substances they see. Therefore, etc. — The consequence is proved. Because from the knowledge of effects the desire to know causes is aroused: and the desire of knowing, naturally implanted in all intellectual substances, does not rest unless, having known the substances of the effects, they also know the substance of the cause.

Thirdly. Those who see that something is, naturally desire to know why it is. Therefore, those who see whether it is, desire to know what it is, which is to understand the substance of the thing. Therefore, neither does the natural desire of knowing come to rest in that knowledge of God by which only whether He is is known of Him. — The first consequence is proved. Because just as the question why is related to the question whether it is, so the question what it is is related to the question whether it is, as is said in II Posteriorum: for in both cases the middle term of demonstration is sought. — How these questions are related was shown in our annotations on II Posteriorum.

Fourthly. The height and power of any created substance is finite. Therefore, the intellect of a separate substance does not rest by the fact that it knows created substances, however eminent, but tends toward knowing the infinite substance. — The consequence is proved. Because nothing finite can quiet the desire of the intellect: for we see that, given any finite thing, such as a line or a number, it strives to apprehend something beyond ².

Fifthly. Separate substances know that the divine substance is unknown to them: since they know, by the aforesaid mode of knowledge, that it is above them, and above everything that is understood by them. Therefore, etc. — The consequence is proved. Because in all intellectual natures there is a natural desire to dispel ignorance or un-knowing, just as there is a natural desire to know.

Sixthly. The intellects of separate substances are closer to divine knowledge than our intellect is. Therefore, they desire divine knowledge more intensely than we do. Therefore, etc. — The first consequence is proved. Because the closer something is to an end, the greater the desire with which it tends toward the end. This is shown in the motions of natural things. — And the second consequence is proved. Because we, however much we know the aforesaid things about God, do not rest in desire, but still desire to see God through His essence.

Note, from the teaching of St. Thomas on I Cael., lect. 17, and II Cael., lect. 8, that natural motion is swifter at the end than at the beginning, because the formal principle by which a natural body is moved is strengthened by proximity to its proper place. But just as motion is more intense and swifter from the strengthening of the natural principle on account of its drawing near to its proper place, so we can say that the closer something is by nature to an end, the more it is inclined toward the end. And thus, because the intellect of a separate substance according to its nature is closer to divine knowledge than our intellect is, as being of a higher order, it is therefore more inclined toward divine knowledge than our intellect is. And thus we can interpret this reason as being grounded upon the proximity of the intellect of a separate substance, considered absolutely, to the knowledge of God.

We can also interpret it as being grounded upon the proximity of an intellect of this kind, not considered absolutely, but taken as it stands under knowledge, by assimilating its natural knowledge to the motion of natural things. For then the reason will proceed thus: that because the intellect of a separate substance, from the fact that it knows God naturally as to certain things, is closer to divine knowledge than our intellect is from its natural knowledge which it has of God—since the separate substance's knowledge of God is clearer and more eminent, as was shown in the preceding chapter, than ours—it is therefore inclined with a greater desire toward knowing the divine substance than our intellect is.

II. As to the fourth point ³, St. Thomas infers the solution of what he had proposed in chapter 49: namely, that the ultimate beatitude of a separate substance does not consist in that knowledge of God by which they know Him through their own essences. — It is proved. Because through it their natural desire is not quieted, but is still carried all the way to the substance of God.

He further concludes from the aforesaid that ultimate human beatitude is to be sought in no other thing than in the operation of the intellect. He proves this, because no other desire is carried so high as the desire to know the truth: since all other desires can rest in other things, whereas the aforesaid desire does not rest unless it reaches the highest hinge and maker of things. Which is also shown by the authority of Eccli. 24 and Prov. 9.

In the last place, he rebukes worldly men, who seek man's beatitude, situated so very high, in the lowest things.

Concerning that proposition, All other desires can rest in other things, it must be observed that it is not the mind of St. Thomas to say that something other than God can so quiet the appetite that nothing else is desired simpliciter, because, as is clear, this would conflict with what was said before; but rather that, taking any desire regarding a determinate created desirable object, the desire can so rest in it that it will desire nothing further of that kind. For instance, one desiring what is sweet can find something so sweet that he will desire nothing sweeter, and so with the others. But the desire to know the truth is quieted in the knowledge of no created thing, but only in the knowledge of the divine substance.

III. Finally, it must be observed that from these things St. Thomas leaves it manifest that the ultimate beatitude of man, or of an intellectual nature, consists in that knowledge by which the divine substance itself is seen—which was principally intended throughout the entire preceding process ⁴—because nothing else, as has been shown, can quiet man's natural desire.