Summa Th. I-II EN Qu.99 a.5
Objection: 1. It would seem that the Old Law contains others besides the moral, judicial, and ceremonial precepts. Because the judicial precepts belong to the act of justice, which is between man and man; while the ceremonial precepts belong to the act of religion, whereby God is worshipped. Now besides these there are many other virtues, viz. temperance, fortitude, liberality, and several others, as stated above (Question , Article ). Therefore besides the aforesaid precepts, the Old Law should comprise others.
2. Further, it is written (Dt 11,1): "Love the Lord thy God, and observe His precepts and ceremonies, His judgments and commandments." Now precepts concern moral matters, as stated above (Article ). Therefore besides the moral, judicial and ceremonial precepts, the Law contains others which are called "commandments." [*The "commandments" (mandata) spoken of here and in the body of this article are not to be confused with the Commandments (praecepta) in the ordinary acceptance of the word.]
3. Further, it is written (Dt 6,17): "Keep the precepts of the Lord thy God, and the testimonies and ceremonies which I have [Vulg.: 'He hath'] commanded thee." Therefore in addition to the above, the Law comprises "testimonies."
4. Further, it is written (Ps 118,93): "Thy justifications (i.e. "Thy Law," according to a gloss) I will never forget." Therefore in the Old Law there are not only moral, ceremonial and judicial precepts, but also others, called "justifications."
On the contrary It is written (Dt 6,1): "These are the precepts and ceremonies and judgments which the Lord your God commanded . . . you." And these words are placed at the beginning of the Law. Therefore all the precepts of the Law are included under them.
I answer that Some things are included in the Law by way of precept; other things, as being ordained to the fulfilment of the precepts. Now the precepts refer to things which have to be done: and to their fulfilment man is induced by two considerations, viz. the authority of the lawgiver, and the benefit derived from the fulfilment, which benefit consists in the attainment of some good, useful, pleasurable or virtuous, or in the avoidance of some contrary evil. Hence it was necessary that in the Old Law certain things should be set forth to indicate the authority of God the lawgiver: e.g. Dt 6,4: "Hear, O Israel, the Lord our God is one Lord"; and Gn 1,1: "In the beginning God created heaven and earth": and these are called "testimonies." Again it was necessary that in the Law certain rewards should be appointed for those who observe the Law, and punishments for those who transgress; as it may be seen in Dt 28: "If thou wilt hear the voice of the Lord thy God . . . He will make thee higher than all the nations," etc.: and these are called "justifications," according as God punishes or rewards certain ones justly.The things that have to be done do not come under the precept except in so far as they have the character of a duty. Now a duty is twofold: one according to the rule of reason; the other according to the rule of a law which prescribes that duty: thus the Philosopher distinguishes a twofold just---moral and legal (Ethic. v, 7).Moral duty is twofold: because reason dictates that something must be done, either as being so necessary that without it the order of virtue would be destroyed; or as being useful for the better maintaining of the order of virtue. And in this sense some of the moral precepts are expressed by way of absolute command or prohibition, as "Thou shalt not kill, Thou shalt not steal": and these are properly called "precepts." Other things are prescribed or forbidden, not as an absolute duty, but as something better to be done. These may be called "commandments"; because they are expressed by way of inducement and persuasion: an example whereof is seen in Ex 22,26: "If thou take of thy neighbor a garment in pledge, thou shalt give it him again before sunset"; and in other like cases. Wherefore Jerome (Praefat. in Comment. super ) says that "justice is in the precepts, charity in the commandments." Duty as fixed by the Law, belongs to the judicial precepts, as regards human affairs; to the "ceremonial" precepts, as regards Divine matters.Nevertheless those ordinances also which refer to punishments and rewards may be called "testimonies," in so far as they testify to the Divine justice. Again all the precepts of the Law may be styled "justifications," as being executions of legal justice. Furthermore the commandments may be distinguished from the precepts, so that those things be called "precepts" which God Himself prescribed; and those things "commandments" which He enjoined [mandavit] through others, as the very word seems to denote.From this it is clear that all the precepts of the Law are either moral, ceremonial, or judicial; and that other ordinances have not the character of a precept, but are directed to the observance of the precepts, as stated above.
Reply to Objection: 1. Justice alone, of all the virtues, implies the notion of duty. Consequently moral matters are determinable by law in so far as they belong to justice: of which virtue religion is a part, as Tully says (De Invent. ii). Wherefore the legal just cannot be anything foreign to the ceremonial and judicial precepts.
2.3.4. The Replies to the other Objections are clear from what has been said.
Objection: 1. It would seem that the Old Law should not have induced men to the observance of its precepts, by means of temporal promises and threats. For the purpose of the Divine law is to subject man to God by fear and love: hence it is written (Dt 10,12): "And now, Israel, what doth the Lord thy God require of thee, but that thou fear the Lord thy God, and walk in His ways, and love Him?" But the desire for temporal goods leads man away from God: for Augustine says (Qq. lxxxiii, qu. 36), that "covetousness is the bane of charity." Therefore temporal promises and threats seem to be contrary to the intention of a lawgiver: and this makes a law worthy of rejection, as the Philosopher declares (Polit. ii, 6).
2. Further, the Divine law is more excellent than human law. Now, in sciences, we notice that the loftier the science, the higher the means of persuasion that it employs. Therefore, since human law employs temporal threats and promises, as means of persuading man, the Divine law should have used, not these, but more lofty means.
3. Further, the reward of righteousness and the punishment of guilt cannot be that which befalls equally the good and the wicked. But as stated in Qo 9,2, "all" temporal "things equally happen to the just and to the wicked, to the good and the evil, to the clean and to the unclean, to him that offereth victims, and to him that despiseth sacrifices." Therefore temporal goods or evils are not suitably set forth as punishments or rewards of the commandments of the Divine law.
On the contrary It is written (Is 1,19-20): "If you be willing, and will hearken to Me, you shall eat the good things of the land. But if you will not, and will provoke Me to wrath: the sword shall devour you."
I answer that As in speculative sciences men are persuaded to assent to the conclusions by means of syllogistic arguments, so too in every law, men are persuaded to observe its precepts by means of punishments and rewards. Now it is to be observed that, in speculative sciences, the means of persuasion are adapted to the conditions of the pupil: wherefore the process of argument in sciences should be ordered becomingly, so that the instruction is based on principles more generally known. And thus also he who would persuade a man to the observance of any precepts, needs to move him at first by things for which he has an affection; just as children are induced to do something, by means of little childish gifts. Now it has been said above (Question , Articles ,2,3) that the Old Law disposed men to (the coming of) Christ, as the imperfect in comparison disposes to the perfect, wherefore it was given to a people as yet imperfect in comparison to the perfection which was to result from Christ's coming: and for this reason, that people is compared to a child that is still under a pedagogue (Ga 3,24). But the perfection of man consists in his despising temporal things and cleaving to things spiritual, as is clear from the words of the Apostle (Ph 3,13 Ph 3,15): "Forgetting the things that are behind, I stretch [Vulg.: 'and stretching'] forth myself to those that are before . . . Let us therefore, as many as are perfect, be thus minded." Those who are yet imperfect desire temporal goods, albeit in subordination to God: whereas the perverse place their end in temporalities. It was therefore fitting that the Old Law should conduct men to God by means of temporal goods for which the imperfect have an affection.
Reply to Objection: 1. Covetousness whereby man places his end in temporalities, is the bane of charity. But the attainment of temporal goods which man desires in subordination to God is a road leading the imperfect to the love of God, according to Ps 48,19: "He will praise Thee, when Thou shalt do well to him."
2. Human law persuades men by means of temporal rewards or punishments to be inflicted by men: whereas the Divine law persuades men by meas of rewards or punishments to be received from God. In this respect it employs higher means.
3. As any one can see, who reads carefully the story of the Old Testament, the common weal of the people prospered under the Law as long as they obeyed it; and as soon as they departed from the precepts of the Law they were overtaken by many calamities. But certain individuals, although they observed the justice of the Law, met with misfortunes---either because they had already become spiritual (so that misfortune might withdraw them all the more from attachment to temporal things, and that their virtue might be tried)---or because, while outwardly fulfilling the works of the Law, their heart was altogether fixed on temporal goods, and far removed from God, according to Is 29,13 (Mt 15,8): "This people honoreth Me with their lips; but their hearts is far from Me."
We must now consider each kind of precept of the Old Law: and (1) the moral precepts, (2) the ceremonial precepts, (3) the judicial precepts. Under the first head there are twelve points of inquiry:
(1) Whether all the moral precepts of the Old Law belong to the law of nature?
(2) Whether the moral precepts of the Old Law are about the acts of all the virtues?
(3) Whether all the moral precepts of the Old Law are reducible to the ten precepts of the decalogue?
(4) How the precepts of the decalogue are distinguished from one another?
(5) Their number;
(6) Their order;
(7) The manner in which they were given;
(8) Whether they are dispensable?
(9) Whether the mode of observing a virtue comes under the precept of the Law?
(10) Whether the mode of charity comes under the precept?
(11) The distinction of other moral precepts;
(12) Whether the moral precepts of the Old Law justified man?
Objection: 1. It would seem that not all the moral precepts belong to the law of nature. For it is written (Si 17,9): "Moreover He gave them instructions, and the law of life for an inheritance." But instruction is in contradistinction to the law of nature; since the law of nature is not learnt, but instilled by natural instinct. Therefore not all the moral precepts belong to the natural law.
2. Further, the Divine law is more perfect than human law. But human law adds certain things concerning good morals, to those that belong to the law of nature: as is evidenced by the fact that the natural law is the same in all men, while these moral institutions are various for various people. Much more reason therefore was there why the Divine law should add to the law of nature, ordinances pertaining to good morals.
3. Further, just as natural reason leads to good morals in certain matters, so does faith: hence it is written (Ga 5,6) that faith "worketh by charity." But faith is not included in the law of nature; since that which is of faith is above nature. Therefore not all the moral precepts of the Divine law belong to the law of nature.
On the contrary The Apostle says (Rm 2,14) that "the Gentiles, who have not the Law, do by nature those things that are of the Law": which must be understood of things pertaining to good morals. Therefore all the moral precepts of the Law belong to the law of nature.
I answer that The moral precepts, distinct from the ceremonial and judicial precepts, are about things pertaining of their very nature to good morals. Now since human morals depend on their relation to reason, which is the proper principle of human acts, those morals are called good which accord with reason, and those are called bad which are discordant from reason. And as every judgment of speculative reason proceeds from the natural knowledge of first principles, so every judgment of practical reason proceeds from principles known naturally, as stated above (Question , Articles ,4): from which principles one may proceed in various ways to judge of various matters. For some matters connected with human actions are so evident, that after very little consideration one is able at once to approve or disapprove of them by means of these general first principles: while some matters cannot be the subject of judgment without much consideration of the various circumstances, which all are not competent to do carefully, but only those who are wise: just as it is not possible for all to consider the particular conclusions of sciences, but only for those who are versed in philosophy: and lastly there are some matters of which man cannot judge unless he be helped by Divine instruction; such as the articles of faith.It is therefore evident that since the moral precepts are about matters which concern good morals; and since good morals are those which are in accord with reason; and since also every judgment of human reason must needs by derived in some way from natural reason; it follows, of necessity, that all the moral precepts belong to the law of nature; but not all in the same way. For there are certain things which the natural reason of every man, of its own accord and at once, judges to be done or not to be done: e.g. "Honor thy father and thy mother," and "Thou shalt not kill, Thou shalt not steal": and these belong to the law of nature absolutely. And there are certain things which, after a more careful consideration, wise men deem obligatory. Such belong to the law of nature, yet so that they need to be inculcated, the wiser teaching the less wise: e.g. "Rise up before the hoary head, and honor the person of the aged man," and the like. And there are some things, to judge of which, human reason needs Divine instruction, whereby we are taught about the things of God: e.g. "Thou shalt not make to thyself a graven thing, nor the likeness of anything; Thou shalt not take the name of the Lord thy God in vain."
This suffices for the Replies to the Objections.
Objection: 1. It would seem that the moral precepts of the Law are not about all the acts of virtue. For observance of the precepts of the Old Law is called justification, according to Ps 118,8: "I will keep Thy justifications." But justification is the execution of justice. Therefore the moral precepts are only about acts of justice.
2. Further, that which comes under a precept has the character of a duty. But the character of duty belongs to justice alone and to none of the other virtues, for the proper act of justice consists in rendering to each one his due. Therefore the precepts of the moral law are not about the acts of the other virtues, but only about the acts of justice.
3. Further, every law is made for the common good, as Isidore says (Etym. v, 21). But of all the virtues justice alone regards the common good, as the Philosopher says (Ethic. v, 1). Therefore the moral precepts are only about the acts of justice.
On the contrary Ambrose says (De Paradiso viii) that "a sin is a transgression of the Divine law, and a disobedience to the commandments of heaven." But there are sins contrary to all the acts of virtue. Therefore it belongs to Divine law to direct all the acts of virtue.
I answer that Since the precepts of the Law are ordained to the common good, as stated above (Question , Article ), the precepts of the Law must needs be diversified according to the various kinds of community: hence the Philosopher (Polit. iv, 1) teaches that the laws which are made in a state which is ruled by a king must be different from the laws of a state which is ruled by the people, or by a few powerful men in the state. Now human law is ordained for one kind of community, and the Divine law for another kind. Because human law is ordained for the civil community, implying mutual duties of man and his fellows: and men are ordained to one another by outward acts, whereby men live in communion with one another. This life in common of man with man pertains to justice, whose proper function consists in directing the human community. Wherefore human law makes precepts only about acts of justice; and if it commands acts of other virtues, this is only in so far as they assume the nature of justice, as the Philosopher explains (Ethic. v, 1).But the community for which the Divine law is ordained, is that of men in relation to God, either in this life or in the life to come. And therefore the Divine law proposes precepts about all those matters whereby men are well ordered in their relations to God. Now man is united to God by his reason or mind, in which is God's image. Wherefore the Divine law proposes precepts about all those matters whereby human reason is well ordered. But this is effected by the acts of all the virtues: since the intellectual virtues set in good order the acts of the reason in themselves: while the moral virtues set in good order the acts of the reason in reference to the interior passions and exterior actions. It is therefore evident that the Divine law fittingly proposes precepts about the acts of all the virtues: yet so that certain matters, without which the order of virtue, which is the order of reason, cannot even exist, come under an obligation of precept; while other matters, which pertain to the well-being of perfect virtue, come under an admonition of counsel.
Reply to Objection: 1. The fulfilment of the commandments of the Law, even of those which are about the acts of the other virtues, has the character of justification, inasmuch as it is just that man should obey God: or again, inasmuch as it is just that all that belongs to man should be subject to reason.
2. Justice properly so called regards the duty of one man to another: but all the other virtues regard the duty of the lower powers to reason. It is in relation to this latter duty that the Philosopher speaks (Ethic. v, 11) of a kind of metaphorical justice.
3. The Reply to the Third Objection is clear from what has been said about the different kinds of community.
Objection: 1. It would seem that not all the moral precepts of the Old Law are reducible to the ten precepts of the decalogue. For the first and principal precepts of the Law are, "Thou shalt love the Lord thy God," and "Thou shalt love thy neighbor," as stated in Mt 22,37 Mt 22,39. But these two are not contained in the precepts of the decalogue. Therefore not all the moral precepts are contained in the precepts of the decalogue.
2. Further, the moral precepts are not reducible to the ceremonial precepts, but rather vice versa. But among the precepts of the decalogue, one is ceremonial, viz. "Remember that thou keep holy the Sabbath-day." Therefore the moral precepts are not reducible to all the precepts of the decalogue.
3. Further, the moral precepts are about all the acts of virtue. But among the precepts of the decalogue are only such as regard acts of justice; as may be seen by going through them all. Therefore the precepts of the decalogue do not include all the moral precepts.
On the contrary The gloss on Mt 5,11: "Blessed are ye when they shall revile you," etc. says that "Moses, after propounding the ten precepts, set them out in detail." Therefore all the precepts of the Law are so many parts of the precepts of the decalogue.
I answer that The precepts of the decalogue differ from the other precepts of the Law, in the fact that God Himself is said to have given the precepts of the decalogue; whereas He gave the other precepts to the people through Moses. Wherefore the decalogue includes those precepts the knowledge of which man has immediately from God. Such are those which with but slight reflection can be gathered at once from the first general principles: and those also which become known to man immediately through divinely infused faith. Consequently two kinds of precepts are not reckoned among the precepts of the decalogue: viz. first general principles, for they need no further promulgation after being once imprinted on the natural reason to which they are self-evident; as, for instance, that one should do evil to no man, and other similar principles: and again those which the careful reflection of wise men shows to be in accord with reason; since the people receive these principles from God, through being taught by wise men. Nevertheless both kinds of precepts are contained in the precepts of the decalogue; yet in different ways. For the first general principles are contained in them, as principles in their proximate conclusions; while those which are known through wise men are contained, conversely, as conclusions in their principles.
Reply to Objection: 1. Those two principles are the first general principles of the natural law, and are self-evident to human reason, either through nature or through faith. Wherefore all the precepts of the decalogue are referred to these, as conclusions to general principles.
2. The precept of the Sabbath observance is moral in one respect, in so far as it commands man to give some time to the things of God, according to Ps 45,11: "Be still and see that I am God." In this respect it is placed among the precepts of the decalogue: but not as to the fixing of the time, in which respect it is a ceremonial precept.
3. The notion of duty is not so patent in the other virtues as it is in justice. Hence the precepts about the acts of the other virtues are not so well known to the people as are the precepts about acts of justice. Wherefore the acts of justice especially come under the precepts of the decalogue, which are the primary elements of the Law.
Objection: 1. It would seem that the precepts of the decalogue are unsuitably distinguished from one another. For worship is a virtue distinct from faith. Now the precepts are about acts of virtue. But that which is said at the beginning of the decalogue, "Thou shalt not have strange gods before Me," belongs to faith: and that which is added, "Thou shalt not make . . . any graven thing," etc. belongs to worship. Therefore these are not one precept, as Augustine asserts (Qq. in Exod. qu. lxxi), but two.
2. Further, the affirmative precepts in the Law are distinct from the negative precepts; e.g. "Honor thy father and thy mother," and, "Thou shalt not kill." But this, "I am the Lord thy God," is affirmative: and that which follows, "Thou shalt not have strange gods before Me," is negative. Therefore these are two precepts, and do not, as Augustine says (Qq. in Exod. qu. lxxi), make one.
3. Further, the Apostle says (Rm 7,7): "I had not known concupiscence, if the Law did not say: 'Thou shalt not covet.'" Hence it seems that this precept, "Thou shalt not covet," is one precept; and, therefore, should not be divided into two.
On the contrary stands the authority of Augustine who, in commenting on Exodus (Qq. in Exod. qu. lxxi) distinguishes three precepts as referring to God, and seven as referring to our neighbor.
I answer that The precepts of the decalogue are differently divided by different authorities. For Hesychius commenting on Lv 26,26, "Ten women shall bake your bread in one oven," says that the precept of the Sabbath-day observance is not one of the ten precepts, because its observance, in the letter, is not binding for all time. But he distinguishes four precepts pertaining to God, the first being, "I am the Lord thy God"; the second, "Thou shalt not have strange gods before Me," (thus also Jerome distinguishes these two precepts, in his commentary on Os 10,10, "On thy" [Vulg.: "their"] "two iniquities"); the third precept according to him is, "Thou shalt not make to thyself any graven thing"; and the fourth, "Thou shalt not take the name of the Lord thy God in vain." He states that there are six precepts pertaining to our neighbor; the first, "Honor thy father and thy mother"; the second, "Thou shalt not kill"; the third, "Thou shalt not commit adultery"; the fourth, "Thou shalt not steal"; the fifth, "Thou shalt not bear false witness"; the sixth, "Thou shalt not covet."But, in the first place, it seems unbecoming for the precept of the Sabbath-day observance to be put among the precepts of the decalogue, if it nowise belonged to the decalogue. Secondly, because, since it is written (Mt 6,24), "No man can serve two masters," the two statements, "I am the Lord thy God," and, "Thou shalt not have strange gods before Me" seem to be of the same nature and to form one precept. Hence Origen (Hom. viii in ) who also distinguishes four precepts as referring to God, unites these two under one precept; and reckons in the second place, "Thou shalt not make . . . any graven thing"; as third, "Thou shalt not take the name of the Lord thy God in vain"; and as fourth, "Remember that thou keep holy the Sabbath-day." The other six he reckons in the same way as Hesychius.Since, however, the making of graven things or the likeness of anything is not forbidden except as to the point of their being worshipped as gods---for God commanded an image of the Seraphim [Vulg.: Cherubim] to be made and placed in the tabernacle, as related in Ex 25,18 ---Augustine more fittingly unites these two, "Thou shalt not have strange gods before Me," and, "Thou shalt not make . . . any graven thing," into one precept. Likewise to covet another's wife, for the purpose of carnal knowledge, belongs to the concupiscence of the flesh; whereas, to covet other things, which are desired for the purpose of possession, belongs to the concupiscence of the eyes; wherefore Augustine reckons as distinct precepts, that which forbids the coveting of another's goods, and that which prohibits the coveting of another's wife. Thus he distinguishes three precepts as referring to God, and seven as referring to our neighbor. And this is better.
Reply to Objection: 1. Worship is merely a declaration of faith: wherefore the precepts about worship should not be reckoned as distinct from those about faith. Nevertheless precepts should be given about worship rather than about faith, because the precept about faith is presupposed to the precepts of the decalogue, as is also the precept of charity. For just as the first general principles of the natural law are self-evident to a subject having natural reason, and need no promulgation; so also to believe in God is a first and self-evident principle to a subject possessed of faith: "for he that cometh to God, must believe that He is" (He 11,6). Hence it needs no other promulgation that the infusion of faith.
2. The affirmative precepts are distinct from the negative, when one is not comprised in the other: thus that man should honor his parents does not include that he should not kill another man; nor does the latter include the former. But when an affirmative precept is included in a negative, or vice versa, we do not find that two distinct precepts are given: thus there is not one precept saying that "Thou shalt not steal," and another binding one to keep another's property intact, or to give it back to its owner. In the same way there are not different precepts about believing in God, and about not believing in strange gods.
3. All covetousness has one common ratio: and therefore the Apostle speaks of the commandment about covetousness as though it were one. But because there are various special kinds of covetousness, therefore Augustine distinguishes different prohibitions against coveting: for covetousness differs specifically in respect of the diversity of actions or things coveted, as the Philosopher says (Ethic. x, 5).
Objection: 1. It would seem that the precepts of the decalogue are unsuitably set forth. Because sin, as stated by Ambrose (De Paradiso viii), is "a transgression of the Divine law and a disobedience to the commandments of heaven." But sins are distinguished according as man sins against God, or his neighbor, or himself. Since, then, the decalogue does not include any precepts directing man in his relations to himself, but only such as direct him in his relations to God and himself, it seems that the precepts of the decalogue are insufficiently enumerated.
2. Further, just as the Sabbath-day observance pertained to the worship of God, so also did the observance of other solemnities, and the offering of sacrifices. But the decalogue contains a precept about the Sabbath-day observance. Therefore it should contain others also, pertaining to the other solemnities, and to the sacrificial rite.
3. Further, as sins against God include the sin of perjury, so also do they include blasphemy, or other ways of lying against the teaching of God. But there is a precept forbidding perjury, "Thou shalt not take the name of the Lord thy God in vain." Therefore there should be also a precept of the decalogue forbidding blasphemy and false doctrine.
4. Further, just as man has a natural affection for his parents, so has he also for his children. Moreover the commandment of charity extends to all our neighbors. Now the precepts of the decalogue are ordained unto charity, according to 1Tm 1,5: "The end of the commandment is charity." Therefore as there is a precept referring to parents, so should there have been some precepts referring to children and other neighbors.
5. Further, in every kind of sin, it is possible to sin in thought or in deed. But in some kinds of sin, namely in theft and adultery, the prohibition of sins of deed, when it is said, "Thou shalt not commit adultery, Thou shalt not steal," is distinct from the prohibition of the sin of thought, when it is said, "Thou shalt not covet thy neighbor's goods," and, "Thou shalt not covet thy neighbor's wife." Therefore the same should have been done in regard to the sins of homicide and false witness.
6. Further, just as sin happens through disorder of the concupiscible faculty, so does it arise through disorder of the irascible part. But some precepts forbid inordinate concupiscence, when it is said, "Thou shalt not covet." Therefore the decalogue should have included some precepts forbidding the disorders of the irascible faculty. Therefore it seems that the ten precepts of the decalogue are unfittingly enumerated.
On the contrary It is written (Dt 4,13): "He shewed you His covenant, which He commanded you to do, and the ten words that He wrote in two tablets of stone."
I answer that As stated above (Article ), just as the precepts of human law direct man in his relations to the human community, so the precepts of the Divine law direct man in his relations to a community or commonwealth of men under God. Now in order that any man may dwell aright in a community, two things are required: the first is that he behave well to the head of the community; the other is that he behave well to those who are his fellows and partners in the community. It is therefore necessary that the Divine law should contain in the first place precepts ordering man in his relations to God; and in the second place, other precepts ordering man in his relations to other men who are his neighbors and live with him under God.Now man owes three things to the head of the community: first, fidelity; secondly, reverence; thirdly, service. Fidelity to his master consists in his not giving sovereign honor to another: and this is the sense of the first commandment, in the words "Thou shalt not have strange gods." Reverence to his master requires that he should do nothing injurious to him: and this is conveyed by the second commandment, "Thou shalt not take the name of the Lord thy God in vain." Service is due to the master in return for the benefits which his subjects receive from him: and to this belongs the third commandment of the sanctification of the Sabbath in memory of the creation of all things.To his neighbors a man behaves himself well both in particular and in general. In particular, as to those to whom he is indebted, by paying his debts: and in this sense is to be taken the commandment about honoring one's parents. In general, as to all men, by doing harm to none, either by deed, or by word, or by thought. By deed, harm is done to one's neighbor---sometimes in his person, i.e. as to his personal existence; and this is forbidden by the words, "Thou shalt not kill": sometimes in a person united to him, as to the propagation of offspring; and this is prohibited by the words, "Thou shalt not commit adultery": sometimes in his possessions, which are directed to both the aforesaid; and with this regard to this it is said, "Thou shalt not steal." Harm done by word is forbidden when it is said, "Thou shalt not bear false witness against thy neighbor": harm done by thought is forbidden in the words, "Thou shalt not covet."The three precepts that direct man in his behavior towards God may also be differentiated in this same way. For the first refers to deeds; wherefore it is said, "Thou shalt not make . . . a graven thing": the second, to words; wherefore it is said, "Thou shalt not take the name of the Lord thy God in vain": the third, to thoughts; because the sanctification of the Sabbath, as the subject of a moral precept, requires repose of the heart in God. Or, according to Augustine (In Ps 32, Conc. 1), by the first commandment we reverence the unity of the First Principle; by the second, the Divine truth; by the third, His goodness whereby we are sanctified, and wherein we rest as in our last end.
Reply to Objection: 1. This objection may be answered in two ways. First, because the precepts of the decalogue can be reduced to the precepts of charity. Now there was need for man to receive a precept about loving God and his neighbor, because in this respect the natural law had become obscured on account of sin: but not about the duty of loving oneself, because in this respect the natural law retained its vigor: or again, because love of oneself is contained in the love of God and of one's neighbor: since true self-love consists in directing oneself to God. And for this reason the decalogue includes those precepts only which refer to our neighbor and to God.Secondly, it may be answered that the precepts of the decalogue are those which the people received from God immediately; wherefore it is written (Dt 10,4): "He wrote in the tables, according as He had written before, the ten words, which the Lord spoke to you." Hence the precepts of the decalogue need to be such as the people can understand at once. Now a precept implies the notion of duty. But it is easy for a man, especially for a believer, to understand that, of necessity, he owes certain duties to God and to his neighbor. But that, in matters which regard himself and not another, man has, of necessity, certain duties to himself, is not so evident: for, at the first glance, it seems that everyone is free in matters that concern himself. And therefore the precepts which prohibit disorders of a man with regard to himself, reach the people through the instruction of men who are versed through the instruction of men who are versed in such matters; and, consequently, they are not contained in the decalogue.
2. All the solemnities of the Old Law were instituted in celebration of some Divine favor, either in memory of past favors, or in sign of some favor to come: in like manner all the sacrifices were offered up with the same purpose. Now of all the Divine favors to be commemorated the chief was that of the Creation, which was called to mind by the sanctification of the Sabbath; wherefore the reason for this precept is given in Ex 20,11: "In six days the Lord made heaven and earth," etc. And of all future blessings, the chief and final was the repose of the mind in God, either, in the present life, by grace, or, in the future life, by glory; which repose was also foreshadowed in the Sabbath-day observance: wherefore it is written (Is 58,13): "If thou turn away thy foot from the Sabbath, from doing thy own will in My holy day, and call the Sabbath delightful, and the holy of the Lord glorious." Because these favors first and chiefly are borne in mind by men, especially by the faithful. But other solemnities were celebrated on account of certain particular favors temporal and transitory, such as the celebration of the Passover in memory of the past favor of the delivery from Egypt, and as a sign of the future Passion of Christ, which though temporal and transitory, brought us to the repose of the spiritual Sabbath. Consequently, the Sabbath alone, and none of the other solemnities and sacrifices, is mentioned in the precepts of the decalogue.
3. As the Apostle says (He 6,16), "men swear by one greater than themselves; and an oath for confirmation is the end of all their controversy." Hence, since oaths are common to all, inordinate swearing is the matter of a special prohibition by a precept of the decalogue. According to one interpretation, however, the words, "Thou shalt not take the name of the Lord thy God in vain," are a prohibition of false doctrine, for one gloss expounds them thus: "Thou shalt not say that Christ is a creature."
4. That a man should not do harm to anyone is an immediate dictate of his natural reason: and therefore the precepts that forbid the doing of harm are binding on all men. But it is not an immediate dictate of natural reason that a man should do one thing in return for another, unless he happen to be indebted to someone. Now a son's debt to his father is so evident that one cannot get away from it by denying it: since the father is the principle of generation and being, and also of upbringing and teaching. Wherefore the decalogue does not prescribe deeds of kindness or service to be done to anyone except to one's parents. On the other hand parents do not seem to be indebted to their children for any favors received, but rather the reverse is the case. Again, a child is a part of his father; and "parents love their children as being a part of themselves," as the Philosopher states (Ethic. viii, 12). Hence, just as the decalogue contains no ordinance as to man's behavior towards himself, so, for the same reason, it includes no precept about loving one's children.
5. The pleasure of adultery and the usefulness of wealth, in so far as they have the character of pleasurable or useful good, are of themselves, objects of appetite: and for this reason they needed to be forbidden not only in the deed but also in the desire. But murder and falsehood are, of themselves, objects of repulsion (since it is natural for man to love his neighbor and the truth): and are desired only for the sake of something else. Consequently with regard to sins of murder and false witness, it was necessary to proscribe, not sins of thought, but only sins of deed.
As stated above (Question , Article ), all the passions of the irascible faculty arise from the passions of the concupiscible part. Hence, as the precepts of the decalogue are, as it were, the first elements of the Law, there was no need for mention of the irascible passions, but only of the concupiscible passions.
Summa Th. I-II EN Qu.99 a.5