Some simple and, I hope, non-controversial (accepting that which came before) proofs that God is the ultimate end.
1 It is, consequently, apparent that all things are ordered to one good, as to their ultimate end.
2 If, in fact, nothing tends toward a thing as an end, unless this thing is a good, it is therefore necessary that the good, as good, be the end. Therefore, that which is the highest good is, from the highest point of view, the end of all things. But there is only one highest good, and this is God, as has been demonstrated in Book One . So, all things are ordered to one good, as their end, and this is God.
3 Again, that which is supreme in any genus is the cause of all the members that belong in that genus; thus, fire, which is the hottest of corporeal things, is the cause of the heat of other things. Therefore, the highest good which is God is the cause of the goodness in all good things. So, also, is He the cause of every end that is an end, since whatever is an end is such because it is a good. Now, “the cause of an attribute’s inherence in a subject always itself inheres in the subject more firmly than does the attribute.” Therefore, God is obviously the end of all things.
4 Besides, in any kind of causes, the first cause is more a cause than is the secondary cause, for a secondary cause is only a cause through the primary cause. Therefore, that which is the first cause in the order of final causes must be more the final cause of anything than is its proximate final cause. But God is the first cause in the order of final causes, since He is the highest in the order of goods. Therefore, He is more the end of everything than is any proximate end.
5 Moreover, in every ordered series of ends the ultimate end must be the end of all preceding ends. For instance, if a potion is mixed to be given a sick man, and it is given in order to purge him, and he is purged in order to make him thinner, and he is thinned down so that he may become healthy. Then health must be the end of the thinning process, and of the purging, and of the other actions which precede it. But all things are found, in their various degrees of goodness, to be subordinated to one highest good which is the cause of all goodness. Consequently, since the good has the essential character of an end, all things are subordinated to God, as preceding ends under an ultimate end. Therefore, God must be the end of all things.
Notes Dieting began earlier than supposed.
6 Furthermore, a particular good is ordered to the common good as to an end; indeed, the being of a part depends on the being of the whole. So, also, the good of a nation is more godlike than the good of one man. Now, the highest good which is God is the common good, since the good of all things taken together depends on Him; and the good whereby each thing is good is its own particular good, and also is the good of the other things that depend on this thing. Therefore, all things are ordered to one good as their end, and that is God.
7 Again, order among ends is a consequence of order among agents, for, just as the supreme agent moves all secondary agents, so must all the ends of secondary agents be ordered to the end of the supreme agent, since whatever the supreme agent does, He does for the sake of His end. Now, the supreme agent does the actions of all inferior agents by moving them all to their actions and, consequently, to their ends. Hence, it follows that all the ends of secondary agents are ordered by the first agent to His own proper end. Of course, the first agent of all things is God, as we proved in Book Two . There is no other end for His will than His goodness, which is Himself, as we proved in Book One . Therefore, all things, whether made by Him. immediately, or by means of secondary causes, are ordered to God as to their end. Now, all things are of this kind, for, as we proved in Book Two , there can be nothing that does not take its being from Him. So, all things are ordered to God as an end.
8 Besides, the ultimate end of any maker, as a maker, is himself; we use things made by us for our own sakes, and, if sometimes a man makes a thing for some other purpose, this has reference to his own good, either as useful, delectable, or as a good for its own sake. Now, God is the productive cause of all things, of some immediately, of others by means of other causes, as is shown in the foregoing. Therefore, He Himself is the end of all things.
9 Moreover, the end holds first place over other types of cause, and to it all other causes owe the fact that they are causes in act: for the agent acts only for the sake of the end, as was pointed out. Matter is brought to formal act by the agent, and thus matter actually becomes the matter of this particular thing, as form becomes the form of this thing: through the action of the agent, and consequently through the end. So, too, the posterior end is the cause of the preceding end being intended as an end, for a thing is not moved toward a proximate end unless for the sake of a last end. Therefore, the ultimate end is the first cause of all. Now, to be the first cause of all must be appropriate to the first being, that is, to God, as was shown above. So, God is the ultimate end of all things.
Notes The cause of causes is the end to which acts are directed. The final cause is the first. As such, the word is inapt in English. But we by now have the idea.
10 Thus it is said in Proverbs (16:4): “God made all things for Himself”; and in the Apocalypse (22:13): “I am Alpha and Omega, the First and the Last.”