Chapter 128 — How by the divine law man is directed to his neighbor

Accordingly, from what has been said, (Ch. 121.) it is clear that man is led by the divine law to observe the order of reason in all things that may be of use to him. Now, of all things that may be useful to man, other men hold the first place, since man is by nature a social animal, (Nicomachean Ethics 1.7.) for he needs many things that cannot be provided by one man alone. Therefore, man must be instructed by divine law so as to behave towards other men according to the order of reason.

Again. The end of the divine law is that man may adhere to God. (Ch. 115.) Now, in this, one man is assisted by another both in his knowledge and in his affections, because one man helps another to know the truth, and one urges another to good, and withdraws him from evil. Hence it is said: Iron sharpens iron, and one man sharpens another (Prov 27:17); and: Two are better than one, because they have a good reward for their toil. For if they fall, one will lift up his fellow; but woe to him who is alone when he falls and has not another to lift him up. Again, if two lie together, they are warm; but how can one be warm alone? And though a man might prevail against one who is alone, two will withstand him (Eccl 4:9–12). Therefore, the divine law had to direct the mutual relations between man and man.

Moreover. The divine law is a rule of divine providence for the governance of men. (Ch. 114. seqq.) Now, it belongs to divine providence to keep all things subject to it within the bounds of right order, namely, so that each thing be in its place and degree. Accordingly, the divine law directs men to one another in such a way that each one remains in his own order. This is for men to be at peace with one another, for peace among men is nothing else but rightly ordered harmony, as Augustine says. (Augustine, City of God, bk. 19, ch. 13.)

Besides. Whenever a number of things are subordinate to one, they ought to be harmoniously ordered to one another, else they would hinder one another in following the common end: thus an army is harmoniously ordered to victory, which is the end of the commander-in-chief. Now, every man is ordered to God (Ch. 115.) by the divine law. Therefore, the divine law had to establish an ordered harmony, which is peace, (See preceding paragraph.) among men, lest they be a hindrance to one another.

Hence it is said in the Psalm: He makes peace in your borders (Ps 147:14[147:3]); and our Lord said: I have said this to you, that in me you may have peace (John 16:33).

Now ordered harmony is observed among men when to every one is given his due: and this belongs to justice. (I. Digest. i. de just. et jure, 10.) Therefore it is said: And the effect of justice will be peace (Isa 32:17). Therefore,the divine law had to give precepts of justice that every one might give others their due, and refrain from doing them wrong.

Among men our greatest debt is to our parents. Therefore, the first of the legal precepts that order us to our neighbor (Exod 20:12–17) is: Honor your father and your mother, whereby we are to understand that each one is commanded to give their due both to his parents and to others, according to Romans 13:7: Pay all of them their dues. The next place is given to the precepts that forbid wrong-doing to one’s neighbor: to harm him by deed either in his own person, for it is said: You shall not kill; or in a person united to him, for it is said: You shall not commit adultery; or in external things, for it is said: You shall not steal. We are also forbidden to wrong our neighbor by word, for it is written: You shall not bear false witness against your neighbor. And since God is judge also of hearts, we are forbidden to injure our neighbor in thought by coveting his wife or his goods.

Now man is moved in two ways to observe this justice that is prescribed by the divine law: first, from within; second, from without. From within, when man is willing to observe the precepts of the divine law. This is the result of man’s love of God and his neighbor: for anyone who loves another gives him his due willingly and with pleasure, and gives even more with liberality. Hence the entire fulfilment of the law depends on love, according to the word of the Apostle: Love is the fulfilling of the law (Rom 13:10). Again, our Lord says that on these two commandments, that is, on the love of God and our neighbor, depends all the law (Matt 22:40). But as some have not the inward disposition to do what the law commands willingly and of their own accord, they need to be drawn from without to fulfill the justice of the law. This is done when they fulfill the law through fear of punishment, not as freemen but as slaves. Hence it is said: For when thy judgments are in the earth, namely, by punishing evil-doers, the inhabitants of the world will learn justice (Isa 26:9).

The former, then, are a law to themselves, (Cf. Rom 2:14.) for they have charity, which moves them instead of the law, and makes them act as free men. Therefore, it was necessary for the external law to be made not on their account, but on account of those who are not inclined to well-doing of their own accord. For this reason it is said: The law is not laid down for the just but for the unjust (1 Tim 1:9). But this does not mean that the just are not bound to fulfill the law, as some have wrongly understood; but that they are inclined of their own accord to do justice, even without the law.