I answer that, It is impossible for happiness to consist in power; and this for two reasons. First because power has the nature of principle, as is stated in Metaph. v, 12, whereas happiness has the nature of last end. Secondly, because power has relation to good and evil: whereas happiness is man's proper and perfect good. Wherefore some happiness might consist in the good use of power, which is by virtue, rather than in power itself.
Now four general reasons may be given to prove that happiness consists in none of the foregoing external goods. First, because, since happiness is man's supreme good, it is incompatible with any evil. Now all the foregoing can be found both in good and in evil men. Secondly, because, since it is the nature of happiness to "satisfy of itself," as stated in Ethic. i, 7, having gained happiness, man cannot lack any needful good. But after acquiring any one of the foregoing, man may still lack many goods that are necessary to him; for instance, wisdom, bodily health, and such like. Thirdly, because, since happiness is the perfect good, no evil can accrue to anyone therefrom. This cannot be said of the foregoing: for it is written (Eccles. 5:12) that "riches" are sometimes "kept to the hurt of the owner"; and the same may be said of the other three. Fourthly, because man is ordained to happiness through principles that are in him; since he is ordained thereto naturally. Now the four goods mentioned above are due rather to external causes, and in most cases to fortune; for which reason they are called goods of fortune. Therefore it is evident that happiness nowise consists in the foregoing.
Reply Obj. 1: God's power is His goodness: hence He cannot use His power otherwise than well. But it is not so with men. Consequently it is not enough for man's happiness, that he become like God in power, unless he become like Him in goodness also.
Reply Obj. 2: Just as it is a very good thing for a man to make good use of power in ruling many, so is it a very bad thing if he makes a bad use of it. And so it is that power is towards good and evil.
Reply Obj. 3: Servitude is a hindrance to the good use of power: therefore is it that men naturally shun it; not because man's supreme good consists in power. ________________________
FIFTH ARTICLE [I-II, Q. 2, Art. 5]
Whether Man's Happiness Consists in Any Bodily Good?
Objection 1: It would seem that man's happiness consists in bodily goods. For it is written (Ecclus. 30:16): "There is no riches above the riches of the health of the body." But happiness consists in that which is best. Therefore it consists in the health of the body.
Obj. 2: Further, Dionysius says (Div. Nom. v), that "to be" is better than "to live," and "to live" is better than all that follows. But for man's being and living, the health of the body is necessary. Since, therefore, happiness is man's supreme good, it seems that health of the body belongs more than anything else to happiness.
Obj. 3: Further, the more universal a thing is, the higher the principle from which it depends; because the higher a cause is, the greater the scope of its power. Now just as the causality of the efficient cause consists in its flowing into something, so the causality of the end consists in its drawing the appetite. Therefore, just as the First Cause is that which flows into all things, so the last end is that which attracts the desire of all. But being itself is that which is most desired by all. Therefore man's happiness consists most of all in things pertaining to his being, such as the health of the body.