Summa contra Gentiles3.44 Chapter XLIV. That man’s ultimate happiness does not consist in the knowledge of separate substances as pretended by the aforesaid opinions

But it is impossible to allow that man’s happiness consists in such a knowledge of separate substances as the above mentioned opinions maintained.

For it is of no purpose to strive for an end by means which cannot secure that end. Since then man’s ultimate end is happiness, to which his natural desire tends, it is impossible to assign man’s happiness to that which he cannot obtain: else it would follow that man was made in vain, and that his natural desire is void, which is impossible. Now it is clear from what we have said that it is impossible for man to understand separate substances, as laid down by the above mentioned opinions. Therefore man’s happiness does not consist in such knowledge of separate substances.

Again. In order that the active intellect be united to us as a form so that by it we may understand separate substances, it is required that the generation of the habitual intellect be complete, according to Alexander;? or that all the principles of understanding be actualized in us, according to Averroes: both of which amount to the same, because the habitual intellect is engendered in us, by the principles of understanding being actualized in us. Now all the species of sensible things are understood potentially. Wherefore, in order that the active intellect be joined to a man, it is necessary that he actually understand by his speculative intellect all the natures of sensible things, and all their powers, operations and movements. But it is impossible for a man to know all this through the principles of speculative sciences, whereby we are moved to the conjunction with the active intellect, as they say: for it is not possible to acquire knowledge of all these things, from those which come under the perception of our senses, whence the principles of speculative sciences are derived. Therefore it is impossible for any man to arrive at this conjunction in the way assigned by them: and consequently man’s happiness cannot consist in such a union.

Besides. Granted that it be possible for man to be united to the active intellect in the manner suggested, it is clear that such a perfection is obtainable by very few; so much so that neither they nor any one else, however much they be advanced and skilled in speculative sciences, have dared to boast of having obtained this perfection. In fact all of them have confessed to ignorance of many things: thus Aristotle, speaking of the quadrature of a circle, and of the reasons for the order in heavenly bodies, himself states (2 De Celo v.) that he can only give probable arguments: and he leaves to others to decide what is certain in these things and their movers (11 Metaph. viii.). Now happiness is a common good, to which many can arrive, unless they be prevented, as Aristotle says (1 Ethic. ix.). It is true also of any natural end of a species, that it is obtained by the majority of the members of that species. Therefore man’s ultimate happiness cannot consist in the aforesaid union.

It is clear that Aristotle, whose opinion the philosophers in question endeavoured to follow, did not hold that man’s ultimate happiness consists in a union of this kind. For he proves (1 Et/ic. xiii.) that man’s happiness is an operation of his own according to perfect virtue: wherefore he had to treat specially of the virtues, which he divided into moral and intellectual: and he proves (10 Ethic. vii.) that man’s ultimate happiness consists in contemplation. Hence it follows that it is not seated in the act of a moral virtue; nor of prudence or art, and yet these are intellectual virtues. Consequently it must be an operation according to wisdom which is the chief of the three remaining intellectual virtues, namely wisdom, knowledge and understanding, as he proves in 6 Ethic. vii.: for which reason he declares (10 Ethic. viii.) that the wise man is a happy man. Now according to him (6 Ethic. l.c.) wisdom is one of the speculative sciences, and the head of the others: and at the beginning of the Metaphysics, he gives the name of wisdom to the science of which he purposes to treat. Clearly therefore the opinion of Aristotle was that the ultimate happiness which man is able to obtain in this life, is that knowledge of divine things which can be acquired through the speculative sciences. But this last way of knowing divine things, not through speculative sciences, but by a kind of natural process of generation, was invented by some of his commentators.