Summa contra Gentiles3.24 Chapter XXIV. How even things devoid of knowledge seek the good

It, as we have shown,! the heavenly body is moved by an intelligent substance, and the movement of the heavenly body is directed to generation in this lower world: it follows that the generations and movements of these lower bodies proceed from the intention of an intelligent substance. For the intention of the principal agent bears on the same thing as that of the instrument. Now the heaven is the cause of the movements of lower bodies by reason of its movement with which it is moved by an intelligent substance. Consequently it is as an instrument of an intelligent substance. Therefore the forms and movements of the lower bodies are caused by an intelligent substance; and are intended by it as by a principal agent, and by the heavenly body, as by an instrument.

Now the species of things caused and intended by an intellectual agent must pre-exist in his intellect: just as the forms of the products of art pre-exist in the mind of the craftsman and flow thence into his work. Consequently all forms that are in these lower bodies, and all their movements flow from intellectual forms which are in the intellect of some substance or substances. Hence Boetius says (De Trin. ii.) that forms which are in matter originated in forms that aveimmaterial. In this respect the saying of Plato is verified, that separate forms are the principles of forms that exist in matter: although Plato held them to be fer se, subsistent, and to be the immediate cause of the forms of sensible bodies: whereas we hold them to exist in an intellect, and to cause lower forms through the heavenly movement.

And since whatever is moved by anything per se and not accidentally, is directed thereby towards the end of its movement;? and since the heavenly body is moved by an intellectual substance; and the heavenly body, by its movement, causes all movement in this lower world; it follows of necessity that the heavenly body is directed to the end of its movement, by an intellectual substance, and consequently all lower bodies to their respective ends.

Accordingly it is easy to understand how natural bodies devoid of knowledge are moved and act for the sake of an end. For they tend to an end, as directed thereto by an intelligent substance: in the same way as an arrow, directed by the archer, tends to the mark. Because as the arrow receives its direction to a fixed end through the aim of the archer, so too natural bodies receive an inclination to their natural ends from their natural movers, whence they derive their forms, powers and movements.

Wherefore it is also clear that every work of nature is the work of an intelligent substance: because an effect is ascribed more especially to the direction of the first mover towards the end, than to the instruments which receive that direction. For this reason the operations of nature are seen to proceed in an orderly manner even as the operations of wise man.

It is therefore evident that even things devoid of knowledge can work for an end, and desire good with a natural appetite. Also that they seek a divine likeness, as well as their own perfection. Nor does it matter in which way we express it, the former or the latter. Because by tending to their own perfection, they tend to a good, since a thing is good forasmuch as it is perfect. And according as a thing tends to be good, it tends to a divine likeness: since a thing is like unto God forasmuch as it is good. Now this or that particular good is so far appetible as it bears a likeness to the first goodness. Therefore the reason why a thing tends to its own good, is because it tends to a divine likeness, and not vice versa. It is clear therefore that all Uthings seek a divine likeness as their last end.

A thing’s own good can be understood in several ways. First, in the sense that it is proper to that thing on the part of the individual. Thus an animal desires its own good, when it desires food, whereby its existence is preserved.—Secondly, as being proper to that thing on the part of its species. Thus an animal desires its own good, forasmuch as it desires to beget offspring and to feed it, as well as whatever else conduces to the preservation or defence of the individuals of its species—Thirdly, on the part of the genus. And thus an equivocal agent, for instance the heaven, desires its own good, in causing.—Fourthly, on the part of a likeness of analogy between effect and cause. Thus God, who is outside all genera, gives being to all things on account of his own goodness.

This clearly proves that the more perfect a thing’s power, and the higher its degree of goodness, the more universal its desire for good, and the greater the range of goodness to which its appetite and operation extend. For imperfect things extend no further than their own individual good; but perfect things extend to the good of the species; more perfect things, to the good of the genus; and God who is most perfect in goodness, to the good of all being. Wherefore it is said by some, not without reason, that good, as such, as self-diffusive,’ because the better a thing is, the further does the outpouring of its goodness extend. And since, in every genus, that which is most perfect 1s the exemplar and measure of all that belongs to that genus,’ it follows that God, who is most perfect in goodness, and pours forth his goodness most universally, is in his outpouring the exemplar of all things that pour forth goodness. Now one thing becomes a cause of another by pouring forth its own goodness into that other. And so it is again evident that whatever tends to be the cause of something else, tends to a divine likeness, and yet tends to its own good. Consequently it is not unreasonable to say that the movements of heavenly bodies, and the actions of their movers, are in a way for the sake of these bodies that are generated and corrupted, and of less account than they are. For they are not for the sake of these as their last end: but by intending.the generation of these, they intend their own good, and the divine likeness as their last end.