Summa contra Gentiles1.100 Chapter C. That God is happy

It remains for us to show from the foregoing that God is happy. For happiness is the proper good of every intellectual nature. Since then God is intelligent, His proper good is happiness. Now He is compared to His proper good, not as that which tends to a good not yet possessed—for this belongs to a nature that is changeable and in potentiality, but as that which already possesses its proper good. Wherefore He not only desires happiness, as we do, but enjoys it. Therefore He is happy.

Moreover. An intellectual nature desires and wills above all that which is most perfect in it, and this is its happiness: and the most perfect thing in every being is its most perfect operation: for power and habit are perfected by operation; wherefore the Philosopher says that happiness is a perfect operation Now the perfection of operation depends on four things. First, on its genus, namely that it abide in the operator: and by an operation abiding in the operator I mean one by which nothing else is done besides the operation, for instance to see or to hear. For the like are perfections of those things whose operations they are, and can be something ultimate, because they are not directed to something made as their end. On the other hand, an operation or action from which there follows something done besides the action itself, is a perfection of the thing done, not of the doer, and is compared to the doer as its end. Hence such an operation of the intellectual «4 nature is not beatitude or happiness. Secondly, on the principle of operation, that it should be an operation of the highest power. Hence happiness in us is not by an operation of the senses, but by an operation of the intellect perfected by a habit. Thirdly, on the object of the operation. For this reason ultimate happiness in us consists in understanding the highest object of our intellect. Fourthly, on the form of operation, namely that the operation should be performed perfectly, easily, constantly, and pleasurably. Now such is the operation of God. For He is intelligent; and His intellect is the sovereign power, nor needs to be perfected by a habit, since it is perfect in itself, as we proved above. He also understands Himself, Who is the highest of intelligible objects, perfectly, without any difficulty, and pleasurably. Therefore He is happy.

Again. Every desire is set at rest by happiness; because once it is possessed nothing remains to be desired, for it is the last end. Accordingly He must be happy, since He is perfect in all things that can be desired; wherefore Boethius says that happiness is a state made perfect by the assemblage of all good things. Now such is the divine perfection that it contains every perfection with simplicity, as shown above. Therefore He is truly happy.

Again. As long as a person lacks that which he needs, he is not yet happy: for his desire is not yet set at rest. Whosoever, therefore, is self-sufficient, needing nothing, is happy. Now it was proved above that God needs not other things, since His perfection depends on nothing outside Him: nor does He will other things for His own sake as their end, as though He needed them, but merely because this is befitting His goodness. Therefore He is happy.

Further. It has been proved that God cannot will what is impossible. Now it is impossible for anything to accrue to Him that He has not already, since He is nowise in potentiality, as we have shown. Therefore He cannot will to have what He has not. Whatever then He wills He has. Nor does He will anything ill, as we have proved. Therefore He is happy, according as some assert that a happy man is one who has whatever he desires, and desires nothing amiss.

Holy Writ also bears witness to His happiness (1 Tim. vi.): Which in His times He shall show, Who is blessed and... mighty.