Hence they are not only directed hut also direct their own actions to their proper end. And if by their own direction they are subject to divine rule, they are able to attain the ultimate end; but if by their own direction they depart from it, they are expelled. Things lacking intelligence do not direct themselves to the end but are directed by another. Some of these are incorruptible and neither in their natural being nor in their actions ever depart from the order to the end that has been set them, but are unfailingly THE HUMAN GOOD 2.59 subject to the first ruler: for example, celestial bodies whose motion is always uniform. Other such things are corruptible and can suffer defect in their nature -though this defect can be offset by something arising from it, as the c01'1'l1ption of one is the generation of another -and in their actions, which can deviate from the natural order, though this defect can be compensated for by a good arising from it. From which it is clear that these things do not depart from the order of the first rulcr nor escape his power. These corruptible bodies, having been created by God, are perfectly subject to his power. The Psalmist, therefore, filled with the Holy Spirit and pondering how he might show us the divine rule, first points out to us the perfection of the first ruler: perfection of nature, by calling him God; of power, by calling him the great Lord, as needing only his own power to produce his effect; of authority, by calling him the great King above all the gods, because, though many rule, all are subject to his dominion. Second, he describes for us the manner of his rule first with respect to intellectual beings which, by following his rule, achieve through Him their ultimate end, which is God himself: and therefore he says, because God will not forget his people. Then with respect to cor1'Uptible beings, even if from time to time they deviate in their proper activities, they are not removed from the power of the first ruler, so he says that the ends of the earth are in his hands. With respect to celestial bodies, which surpass the heights of the earth -that is, of corruptible bodies -and always abide by the right ordering of the first ruler, he says that the heights of the mountains are his. Third, he assigns the reason for this universal rule: it is necessary that the things God has made should be governed by him. And this is what he means when he says that the sea is his, etc. Since in the first book we treated of the perfection of the divine nature and in the second of the perfection of his power, insofar as he is the maker and lord of all, it remains for us in this third book to treat of his perfect authority or dignity, insofar as he is the end and ruler of all things.