Consequently when the children of Israel, by God's command, took away the spoils of the Egyptians, this was not theft; since it was due to them by the sentence of God. Likewise when Abraham consented to slay his son, he did not consent to murder, because his son was due to be slain by the command of God, Who is Lord of life and death: for He it is Who inflicts the punishment of death on all men, both godly and ungodly, on account of the sin of our first parent, and if a man be the executor of that sentence by Divine authority, he will be no murderer any more than God would be. Again Osee, by taking unto himself a wife of fornications, or an adulterous woman, was not guilty either of adultery or of fornication: because he took unto himself one who was his by command of God, Who is the Author of the institution of marriage.
Accordingly, therefore, the precepts of the decalogue, as to the essence of justice which they contain, are unchangeable: but as to any determination by application to individual actions—for instance, that this or that be murder, theft or adultery, or not—in this point they admit of change; sometimes by Divine authority alone, namely, in such matters as are exclusively of Divine institution, as marriage and the like; sometimes also by human authority, namely in such matters as are subject to human jurisdiction: for in this respect men stand in the place of God: and yet not in all respects.
Reply Obj. 4: This determination was an interpretation rather than a dispensation. For a man is not taken to break the Sabbath, if he does something necessary for human welfare; as Our Lord proves (Matt. 12:3, seqq.). ________________________
NINTH ARTICLE [I-II, Q. 100, Art. 9]
Whether the Mode of Virtue Falls Under the Precept of the Law?
Objection 1: It would seem that the mode of virtue falls under the precept of the law. For the mode of virtue is that deeds of justice should be done justly, that deeds of fortitude should be done bravely, and in like manner as to the other virtues. But it is commanded (Deut. 26:20) that "thou shalt follow justly after that which is just." Therefore the mode of virtue falls under the precept.
Obj. 2: Further, that which belongs to the intention of the lawgiver comes chiefly under the precept. But the intention of the lawgiver is directed chiefly to make men virtuous, as stated in Ethic. ii: and it belongs to a virtuous man to act virtuously. Therefore the mode of virtue falls under the precept.
Obj. 3: Further, the mode of virtue seems to consist properly in working willingly and with pleasure. But this falls under a precept of the Divine law, for it is written (Ps. 99:2): "Serve ye the Lord with gladness"; and (2 Cor. 9:7): "Not with sadness or necessity: for God loveth a cheerful giver"; whereupon the gloss says: "Whatever ye do, do gladly; and then you will do it well; whereas if you do it sorrowfully, it is done in thee, not by thee." Therefore the mode of virtue falls under the precept of the law.
On the contrary, No man can act as a virtuous man acts unless he has the habit of virtue, as the Philosopher explains (Ethic. ii, 4; v, 8). Now whoever transgresses a precept of the law, deserves to be punished. Hence it would follow that a man who has not the habit of virtue, would deserve to be punished, whatever he does. But this is contrary to the intention of the law, which aims at leading man to virtue, by habituating him to good works. Therefore the mode of virtue does not fall under the precept.
I answer that, As stated above (Q. 90, A. 3, ad 2), a precept of law has compulsory power. Hence that on which the compulsion of the law is brought to bear, falls directly under the precept of the law. Now the law compels through fear of punishment, as stated in Ethic. x, 9, because that properly falls under the precept of the law, for which the penalty of the law is inflicted. But Divine law and human law are differently situated as to the appointment of penalties; since the penalty of the law is inflicted only for those things which come under the judgment of the lawgiver; for the law punishes in accordance with the verdict given. Now man, the framer of human law, is competent to judge only of outward acts; because "man seeth those things that appear," according to 1 Kings 16:7: while God alone, the framer of the Divine law, is competent to judge of the inward movements of wills, according to Ps. 7:10: "The searcher of hearts and reins is God."