Single Question: On the Precepts of the Decalogue and Other Precepts Pertaining to Justice

S. Th. II-II, q. 122; I-II, q. 100, a. 3-7.

896. All the precepts of the decalogue are precepts of justice. - The precepts of the decalogue are the first determined principles of law, to which natural reason at once assents with slight consideration, as to most manifest principles. But the account of debt, which is required for a precept, appears most manifestly in justice, which is toward another: for "in those things which are toward oneself, at first sight it seems that man is master of himself, and that it is licit for him to do anything whatever; but in those things which are toward another, it manifestly appears that man is obligated to another to render him what he owes." Therefore the precepts of the decalogue must pertain to justice (a. 1).

Hence the first three precepts are concerning acts of religion, which is the chief potential part of justice; the fourth is concerning acts of piety, which is second among these; the other six are concerning acts of justice commonly and strictly so called, which is among equals.

897. The ten precepts of the decalogue are fittingly ordered. - This, according to the doctrine of St. Thomas, Billuart proves nearly thus, de virt. iust. adn., diss. 3, a. 11:

The precepts of the decalogue were established for forming man to virtue: for it pertains to law to make men good and virtuous; therefore the precepts of the decalogue had to be ordered according to the order of generation, by which, namely, man becomes good and virtuous. Moreover, in the order of generation two things must be considered:

A. First, that the first part be constituted, as in the generation of man the heart, in a house the foundation: thus in the moral good or goodness of the soul there is goodness of the will, from which someone uses well any other goodness; but the goodness of the will is considered according to its object, which is the end. And therefore in him who was to be instructed to virtue by law, first there had to be made, as it were, a certain foundation of religion, by which man is duly ordered unto God, who is the last end of the human will. I am the Lord thy God (Ex. XX, 2). But because in the order of generation, before the first part is constituted, contraries and impediments must be removed - for the farmer first cleanses the field before he scatters the seed - therefore before all things man had to be instructed in religion in such a way that he would exclude the impediments of true religion. Now then:

I. The chief impediment of true religion is that man adhere to a false god or worship the true God unduly, which constitutes superstition. And for excluding this the first precept is set down: Thou shalt not have strange gods; thou shalt not make for thyself a graven thing, etc.

II. After the first impediment has been excluded, which is opposed to true religion by excess and pertains to superstition, which prevents the true God from being received for worship, another is fittingly removed, which is opposed to religion by defect, and is irreligiosity, which prevents God, after He has been received, from being honored: for it is prior to receive God for worship than to honor Him once received. Therefore, after the precept by which superstition is prohibited has been set down, the second is fittingly set down, by which perjury, or every inordinate and irreverent assumption of the divine name, is prohibited: Thou shalt not take the name of the Lord thy God in vain.

III. The impediments of true religion having been removed through the first and second precepts, it followed that the third precept be set down, by which men would be founded in true religion. But to religion it pertains to exhibit the worship of God; hence the third precept is fittingly set down concerning the sanctification of the Sabbath: Remember that thou sanctify the Sabbath day (that is, of religious rest).

B. But the precepts of the decalogue are ordered not only to love of God but also to love of neighbor, as to an end; but among neighbors we are most obliged to parents, therefore:

IV. Immediately after the precepts ordering us to God, there is set down the fourth precept of piety, ordering us to parents, who are the particular principle of our being, as God is the universal principle: Honor thy father and thy mother; by the name of father and mother understanding also any superiors whatever.

C. Finally, just as by the aforesaid potential parts of justice, namely, religion and piety, a debt is rendered to certain determinate persons, to whom man is obligated from some special account, so by justice itself properly so called someone renders a debt indiscriminately to all. And therefore after the first three precepts pertaining to religion, and after the fourth, which is of piety, by which a special debt is rendered to parents, it was necessary that there be set down consequently some precepts pertaining to justice properly so called, which renders a debt indifferently to all. And for this the last six precepts are set down, by which we are prohibited from inflicting harm upon the neighbor, namely:

V. In his person, which the fifth precept prohibits: Thou shalt not kill, where under homicide, as under the more principal thing, all personal harms are understood.

VI. In the person most conjoined to him through lust, which the sixth precept forbids: Thou shalt not commit adultery.

VII. In exterior bodily things, which the seventh precept prohibits: Thou shalt not steal.

VIII. In external incorporeal things, namely, reputation and honor, which the eighth precept prohibits: Thou shalt not speak false testimony against thy neighbor.

IX. In the very will of committing adultery, which the ninth precept prohibits: Thou shalt not desire thy neighbor's wife.

X. Finally, in the will of stealing, which the tenth forbids: Thou shalt not covet thy neighbor's house, etc.

Indeed by the sixth and seventh precepts, by which adultery and theft are prohibited, without doubt their will is also implicitly prohibited, just as by the fifth and eighth the will of homicide and false testimony is prohibited. Nevertheless, lest someone think that by these precepts only the external works of adultery and theft are prohibited, and not their will, as many among the carnal Jews were, and even now are among rude Christians, God willed to prohibit both of these concupiscences by special and distinct precepts. But He especially prohibited the concupiscence of adultery and theft rather than of homicide and false testimony because adultery has the account of a pleasurable good, theft the account of a useful good, and therefore they more strongly and more frequently allure the soul; but homicide according to itself, as also false testimony, are rather horrible than desirable: for the life of man, as also truth, is naturally loved.

898. Remarks. - 1. The ten precepts of the law have not been distinguished by all in the same manner or order; but this has no bearing on doctrine. We have followed the division which has now become common in the Catholic Church.

2. To the precepts of the decalogue in the Old Law there were added many ceremonial determinations of divine worship, insofar as they are ordered to God, and determinations of justice to be observed among men, insofar as they are ordered to the neighbor. But in the New Law they are abolished; and, certain broad ceremonial precepts having been given concerning sacrifice and the sacraments, the rest which regard religion and divine worship are left to be determined by ecclesiastical law, and those things which regard the manner of preserving justice are rather left to civil law.

3. Many establish a special treatise on the precepts of the decalogue, and not a few divide moral theology according to the precepts. But following the truly scientific method of St. Thomas, who divides moral science according to the virtues, and thus sets it forth altogether completely, it is now useless to treat specially of the precepts, since those things which pertain to them have already been set forth in the present treatise on Justice, or are also going to receive the supplement of exposition from the treatise on Temperance.