On the contrary, It is written ( Jer. 9:23 ): "Let not the wise man glory in his wisdom": and this is said in reference to speculative sciences. Therefore man's final happiness does not consist in the consideration of these.
I answer that, As stated above (A[2], ad 4), man's happiness is twofold, one perfect, the other imperfect. And by perfect happiness we are to understand that which attains to the true notion of happiness; and by imperfect happiness that which does not attain thereto, but partakes of some particular likeness of happiness. Thus perfect prudence is in man, with whom is the idea of things to be done; while imperfect prudence is in certain irrational animals, who are possessed of certain particular instincts in respect of works similar to works of prudence.
Accordingly perfect happiness cannot consist essentially in the consideration of speculative sciences. To prove this, we must observe that the consideration of a speculative science does not extend beyond the scope of the principles of that science: since the entire science is virtually contained in its principles. Now the first principles of speculative sciences are received through the senses, as the Philosopher clearly states at the beginning of the Metaphysics (i, 1), and at the end of the Posterior Analytics (ii, 15). Wherefore the entire consideration of speculative sciences cannot extend farther than knowledge of sensibles can lead. Now man's final happiness, which is his final perfection cannot consist in the knowledge of sensibles. For a thing is not perfected by something lower, except in so far as the lower partakes of something higher. Now it is evident that the form of a stone or of any sensible, is lower than man. Consequently the intellect is not perfected by the form of a stone, as such, but inasmuch as it partakes of a certain likeness to that which is above the human intellect, viz. the intelligible light, or something of the kind. Now whatever is by something else is reduced to that which is of itself. Therefore man's final perfection must needs be through knowledge of something above the human intellect. But it has been shown (FP, Q[88], A[2]), that man cannot acquire through sensibles, the knowledge of separate substances, which are above the human intellect. Consequently it follows that man's happiness cannot consist in the consideration of speculative sciences. However, just as in sensible forms there is a participation of the higher substances, so the consideration of speculative sciences is a certain participation of true and perfect happiness.
Reply to Objection 1: In his book on Ethics the Philosopher treats of imperfect happiness, such as can be had in this life, as stated above (A[2], ad 4).
Reply to Objection 2: Not only is perfect happiness naturally desired, but also any likeness or participation thereof.
Reply to Objection 3: Our intellect is reduced to act, in a fashion, by the consideration of speculative sciences, but not to its final and perfect act.
Whether happiness consists in the knowledge of separate substances, namely, angels?
Objection 1: It would seem that man's happiness consists in the knowledge of separate substances, namely, angels. For Gregory says in a homily (xxvi in Evang.): "It avails nothing to take part in the feasts of men, if we fail to take part in the feasts of angels"; by which he means final happiness. But we can take part in the feasts of the angels by contemplating them. Therefore it seems that man's final happiness consists in contemplating the angels.
Objection 2: Further, the final perfection of each thing is for it to be united to its principle: wherefore a circle is said to be a perfect figure, because its beginning and end coincide. But the beginning of human knowledge is from the angels, by whom men are enlightened, as Dionysius says (Coel. Hier. iv). Therefore the perfection of the human intellect consists in contemplating the angels.
Objection 3: Further, each nature is perfect, when united to a higher nature; just as the final perfection of a body is to be united to the spiritual nature. But above the human intellect, in the natural order, are the angels. Therefore the final perfection of the human intellect is to be united to the angels by contemplation.
On the contrary, It is written ( Jer. 9:24 ): "Let him that glorieth, glory in this, that he understandeth and knoweth Me." Therefore man's final glory or happiness consists only in the knowledge of God.
I answer that, As stated above (A[6]), man's perfect happiness consists not in that which perfects the intellect by some participation, but in that which is so by its essence. Now it is evident that whatever is the perfection of a power is so in so far as the proper formal object of that power belongs to it. Now the proper object of the intellect is the true. Therefore the contemplation of whatever has participated truth, does not perfect the intellect with its final perfection. Since, therefore, the order of things is the same in being and in truth (Metaph ii, 1); whatever are beings by participation, are true by participation. Now angels have being by participation: because in God alone is His Being His Essence, as shown in the FP, Q[44], A[1]. It follows that contemplation of Him makes man perfectly happy. However, there is no reason why we should not admit a certain imperfect happiness in the contemplation of the angels; and higher indeed than in the consideration of speculative science.
Reply to Objection 1: We shall take part in the feasts of the angels, by contemplating not only the angels, but, together with them, also God Himself.
Reply to Objection 2: According to those that hold human souls to be created by the angels, it seems fitting enough, that man's happiness should consist in the contemplation of the angels, in the union, as it were, of man with his beginning. But this is erroneous, as stated in FP, Q[90], A[3]. Wherefore the final perfection of the human intellect is by union with God, Who is the first principle both of the creation of the soul and of its enlightenment. Whereas the angel enlightens as a minister, as stated in the FP, Q[111], A[2], ad 2. Consequently, by his ministration he helps man to attain to happiness; but he is not the object of man's happiness.
Reply to Objection 3: The lower nature may reach the higher in two ways. First, according to a degree of the participating power: and thus man's final perfection will consist in his attaining to a contemplation such as that of the angels. Secondly, as the object is attained by the power: and thus the final perfection of each power is to attain that in which is found the fulness of its formal object.
Whether man's happiness consists in the vision of the divine essence?
Objection 1: It would seem that man's happiness does not consist in the vision of the Divine Essence. For Dionysius says (Myst. Theol. i) that by that which is highest in his intellect, man is united to God as to something altogether unknown. But that which is seen in its essence is not altogether unknown. Therefore the final perfection of the intellect, namely, happiness, does not consist in God being seen in His Essence.
Objection 2: Further, the higher the perfection belongs to the higher nature. But to see His own Essence is the perfection proper to the Divine intellect. Therefore the final perfection of the human intellect does not reach to this, but consists in something less.
On the contrary, It is written ( 1 Jn. 3:2 ): "When He shall appear, we shall be like to Him; and [Vulg.: 'because'] we shall see Him as He is."
I answer that, Final and perfect happiness can consist in nothing else than the vision of the Divine Essence. To make this clear, two points must be observed. First, that man is not perfectly happy, so long as something remains for him to desire and seek: secondly, that the perfection of any power is determined by the nature of its object. Now the object of the intellect is "what a thing is," i.e. the essence of a thing, according to De Anima iii, 6. Wherefore the intellect attains perfection, in so far as it knows the essence of a thing. If therefore an intellect knows the essence of some effect, whereby it is not possible to know the essence of the cause, i.e. to know of the cause "what it is"; that intellect cannot be said to reach that cause simply, although it may be able to gather from the effect the knowledge of that the cause is. Consequently, when man knows an effect, and knows that it has a cause, there naturally remains in the man the desire to know about the cause, "what it is." And this desire is one of wonder, and causes inquiry, as is stated in the beginning of the Metaphysics (i, 2). For instance, if a man, knowing the eclipse of the sun, consider that it must be due to some cause, and know not what that cause is, he wonders about it, and from wondering proceeds to inquire. Nor does this inquiry cease until he arrive at a knowledge of the essence of the cause.
If therefore the human intellect, knowing the essence of some created effect, knows no more of God than "that He is"; the perfection of that intellect does not yet reach simply the First Cause, but there remains in it the natural desire to seek the cause. Wherefore it is not yet perfectly happy. Consequently, for perfect happiness the intellect needs to reach the very Essence of the First Cause. And thus it will have its perfection through union with God as with that object, in which alone man's happiness consists, as stated above (AA[1],7; Q[2], A[8]).
Reply to Objection 1: Dionysius speaks of the knowledge of wayfarers journeying towards happiness.
Reply to Objection 2: As stated above (Q[1], A[8]), the end has a twofold acceptation. First, as to the thing itself which is desired: and in this way, the same thing is the end of the higher and of the lower nature, and indeed of all things, as stated above (Q[1], A[8]). Secondly, as to the attainment of this thing; and thus the end of the higher nature is different from that of the lower, according to their respective habitudes to that thing. So then in the happiness of God, Who, in understanding his Essence, comprehends It, is higher than that of a man or angel who sees It indeed, but comprehends It not.