Summa contra Gentiles3.129 Chapter CXXIX. That some human acts are right by nature, and not because they are prescribed by law

From what has been said it may be seen that the things prescribed by the divine law are right not only because they are prescribed by law, but also by their very nature.

For'the divine law subjects the human mind to God, and all the rest of man, to reason. Now, the natural order 1 Rom. ii. 14.

demands that the inferior be subject to the superior. Therefore the precepts of the divine law are in themselves right by nature.

Further. Divine providence has endowed man with the natural tribunal of reason, as the principle of his own acts. Now, natural principles are directed to things that are naturally. Hence there are certain actions naturally becoming to man, and in themselves right by nature, and not merely because they are prescribed by law.

Moreover. Whatsoever has a determinate nature must have determinate actions, becoming to that nature: since the proper operation of a thing is consequent to its nature. Now, it is clear that man has a determinate nature. Therefore there must needs be certain actions that are in themselves becoming to man.

Besides. If a thing is natural to a man, that also must be natural to him, without which he cannot have that thing: for nature is not wanting in necessaries. Now, it is natural to man to be a social animal, and this is proved by the fact that one man alone does not suffice to procure all the necessities of human life. Consequently whatever is necessary for the maintenance of human society, is naturally becoming to man: such are to observe the rights of others, and to refrain from doing them any harm. Therefore in human acts some things are naturally right.

Also. It has been shown above that it is natural for man to use things beneath him for the needs of his life. Now, there is a certain measure according to which the use of the aforesaid things is expedient for human life, and if that measure be ignored, a wrong is done to man, as in the inordinate consumption of food. Therefore certain human acts are naturally right, and some naturally wrong.

Again. According to the natural order, the body is on account of the soul, and the lower powers of the soul are on account of the reason: even as in other things, matter is for the form, and instruments for the sake of the principal agent. Now, if a thing be ordered to another, it should be a help to it and not a hindrance. Therefore it is naturally right that man should so care for his body and the lower powers of the soul, that they be not a hindrance but a help to the act of reason and to his own good; if it happen otherwise, it will be evil by nature. Therefore wine-bibbing and feasting; inordinate use of venery which hinders the use of reason; and submission to the passions which thwart the free judgement of reason, are all evil by nature.

Moreover. Those things are natural to every man, whereby he tends to his natural end: while those which are of a contrary nature, are naturally unbecoming to him. Now, we have proved above that man is by nature directed to God as his end. Consequently those things whereby man is brought to the knowledge and love of God, are naturally right: and whatever things have a contrary result, are naturally bad for man.

It is therefore clear that good and evil in human acts result not only from the prescription of the law, but also from the order of nature.

Hence it is said in the Psalm (xviii. 10) that the judgements of the Lord are true, justified in themselves.

Hereby we refute the statement of those who assert that the just and the right are prescribed by law only.