Objection 1. It would seem that law is not something pertaining to reason. For the Apostle says (Rm. 7:23): "I see another law in my members," etc. But nothing pertaining to reason is in the members; since the reason does not make use of a bodily organ. Therefore law is not something pertaining to reason.

Objection 2. Further, in the reason there is nothing else but power, habit, and act. But law is not the power itself of reason. In like manner, neither is it a habit of reason: because the habits of reason are the intellectual virtues of which we have spoken above (57). Nor again is it an act of reason: because then law would cease, when the act of reason ceases, for instance, while we are asleep. Therefore law is nothing pertaining to reason.

Objection 3. Further, the law moves those who are subject to it to act aright. But it belongs properly to the will to move to act, as is evident from what has been said above (9, 1). Therefore law pertains, not to the reason, but to the will; according to the words of the Jurist (Lib. i, ff., De Const. Prin. leg. i): "Whatsoever pleaseth the sovereign, has force of law."

On the contrary, It belongs to the law to command and to forbid. But it belongs to reason to command, as stated above (17, 1). Therefore law is something pertaining to reason.

Reply to Objection 1. Since law is a kind of rule and measure, it may be in something in two ways. First, as in that which measures and rules: and since this is proper to reason, it follows that, in this way, law is in the reason alone. Secondly, as in that which is measured and ruled. In this way, law is in all those things that are inclined to something by reason of some law: so that any inclination arising from a law, may be called a law, not essentially but by participation as it were. And thus the inclination of the members to concupiscence is called "the law of the members."

Objection 1. It would seem that the law is not always directed to the common good as to its end. For it belongs to law to command and to forbid. But commands are directed to certain individual goods. Therefore the end of the law is not always the common good.

Objection 2. Further, the law directs man in his actions. But human actions are concerned with particular matters. Therefore the law is directed to some particular good.

Objection 3. Further, Isidore says (Etym. v, 3): "If the law is based on reason, whatever is based on reason will be a law." But reason is the foundation not only of what is ordained to the common good, but also of that which is directed private good. Therefore the law is not only directed to the good of all, but also to the private good of an individual.

On the contrary, Isidore says (Etym. v, 21) that "laws are enacted for no private profit, but for the common benefit of the citizens."

Now in every genus, that which belongs to it chiefly is the principle of the others, and the others belong to that genus in subordination to that thing: thus fire, which is chief among hot things, is the cause of heat in mixed bodies, and these are said to be hot in so far as they have a share of fire. Consequently, since the law is chiefly ordained to the common good, any other precept in regard to some individual work, must needs be devoid of the nature of a law, save in so far as it regards the common good. Therefore every law is ordained to the common good.

Reply to Objection 1. A command denotes an application of a law to matters regulated by the law. Now the order to the common good, at which the law aims, is applicable to particular ends. And in this way commands are given even concerning particular matters.

Reply to Objection 2. Actions are indeed concerned with particular matters: but those particular matters are referable to the common good, not as to a common genus or species, but as to a common final cause, according as the common good is said to be the common end.

Objection 1. It would seem that the reason of any man is competent to make laws. For the Apostle says (Rom. ii. 14) that "when the Gentiles, who have not the law, do by nature those things that are of the law, . . . they are a law to themselves." Now he says this of all in general. Therefore anyone can make a law for himself.

Objection 3. Further, just as the sovereign of a state governs the state, so every father of a family governs his household. But the sovereign of a state can make laws for the state. Therefore every father of a family can make laws for his household.

On the contrary, Isidore says (Etym. v. 10): "A law is an ordinance of the people, whereby something is sanctioned by the Elders together with the Commonalty."

I answer that, A law, properly speaking, regards first and foremost the order to the common good. Now to order anything to the common good, belongs either to the whole people, or to someone who is the viceregent of the whole people. And therefore the making of a law belongs either to the whole people or to a public personage who has care of the whole people: since in all other matters the directing of anything to the end concerns him to whom the end belongs.

Reply to Objection 1. As stated above (A. 1 ad 1), a law is in a person not only as in one that rules, but also by participation as in one that is ruled. In the latter way each one is a law to himself, in so far as he shares the direction that he receives from one who rules him. Hence the same text goes on: "Who shows the work of the law written in their hearts."

Objection 1. It would seem that promulgation is not essential to a law. For the natural law above all has the character of law. But the natural law needs no promulgation. Therefore it is not essential to a law that it be promulgated.

Objection 2. Further, it belongs properly to a law to bind one to do or not to do something. But the obligation of fulfilling a law touches not only those in whose presence it is promulgated, but also others. Therefore promulgation is not essential to a law.

Objection 3. Further, the binding force of a law extends even to the future, since "laws are binding in matters of the future," as the jurists say (Cod. 1, tit. De lege et constit. leg. vii). But promulgation concerns those who are present. Therefore it is not essential to a law.

On the contrary, It is laid down in the Decretals, dist. 4, that "laws are established when they are promulgated."

I answer that, As stated above (1), a law is imposed on others by way of a rule and measure. Now a rule or measure is imposed by being applied to those who are to be ruled and measured by it. Wherefore, in order that a law obtain the binding force which is proper to a law, it must needs be applied to the men who have to be ruled by it. Such application is made by its being notified to them by promulgation. Wherefore promulgation is necessary for the law to obtain its force.

Thus from the four preceding articles, the definition of law may be gathered; and it is nothing else than an ordinance of reason for the common good, made by him who has care of the community, and promulgated.

Reply to Objection 1. The natural law is promulgated by the very fact that God instilled it into man's mind so as to be known by him naturally.

Reply to Objection 2. Those who are not present when a law is promulgated, are bound to observe the law, in so far as it is notified or can be notified to them by others, after it has been promulgated.

Objection 2. Further, promulgation is essential to law. But promulgation could not be from eternity: because there was no one to whom it could be promulgated from eternity. Therefore no law can be eternal.

Objection 3. Further, a law implies order to an end. But nothing ordained to an end is eternal: for the last end alone is eternal. Therefore no law is eternal.

On the contrary, Augustine says (De Lib. Arb. i, 6): "That Law which is the Supreme Reason cannot be understood to be otherwise than unchangeable and eternal."

I answer that, As stated above (90, 1, ad 2; A3,4), a law is nothing else but a dictate of practical reason emanating from the ruler who governs a perfect community. Now it is evident, granted that the world is ruled by Divine Providence, as was stated in the I, 22, A1,2, that the whole community of the universe is governed by Divine Reason. Wherefore the very Idea of the government of things in God the Ruler of the universe, has the nature of a law. And since the Divine Reason's conception of things is not subject to time but is eternal, according to Prov. 8:23, therefore it is that this kind of law must be called eternal.

Reply to Objection 2. Promulgation is made by word of mouth or in writing; and in both ways the eternal law is promulgated: because both the Divine Word and the writing of the Book of Life are eternal. But the promulgation cannot be from eternity on the part of the creature that hears or reads.

Objection 1. It would seem that there is no natural law in us. Because man is governed sufficiently by the eternal law: for Augustine says (De Lib. Arb. i) that "the eternal law is that by which it is right that all things should be most orderly." But nature does not abound in superfluities as neither does she fail in necessaries. Therefore no law is natural to man.

Objection 2. Further, by the law man is directed, in his acts, to the end, as stated above (90, 2). But the directing of human acts to their end is not a function of nature, as is the case in irrational creatures, which act for an end solely by their natural appetite; whereas man acts for an end by his reason and will. Therefore no law is natural to man.

Objection 3. Further, the more a man is free, the less is he under the law. But man is freer than all the animals, on account of his free-will, with which he is endowed above all other animals. Since therefore other animals are not subject to a natural law, neither is man subject to a natural law.

On the contrary, A gloss on Rm. 2:14: "When the Gentiles, who have not the law, do by nature those things that are of the law," comments as follows: "Although they have no written law, yet they have the natural law, whereby each one knows, and is conscious of, what is good and what is evil."

I answer that, As stated above (90, 1, ad 1), law, being a rule and measure, can be in a person in two ways: in one way, as in him that rules and measures; in another way, as in that which is ruled and measured, since a thing is ruled and measured, in so far as it partakes of the rule or measure. Wherefore, since all things subject to Divine providence are ruled and measured by the eternal law, as was stated above (1); it is evident that all things partake somewhat of the eternal law, in so far as, namely, from its being imprinted on them, they derive their respective inclinations to their proper acts and ends. Now among all others, the rational creature is subject to Divine providence in the most excellent way, in so far as it partakes of a share of providence, by being provident both for itself and for others. Wherefore it has a share of the Eternal Reason, whereby it has a natural inclination to its proper act and end: and this participation of the eternal law in the rational creature is called the natural law. Hence the Psalmist after saying (Ps. 4:6): "Offer up the sacrifice of justice," as though someone asked what the works of justice are, adds: "Many say, Who showeth us good things?" in answer to which question he says: "The light of Thy countenance, O Lord, is signed upon us": thus implying that the light of natural reason, whereby we discern what is good and what is evil, which is the function of the natural law, is nothing else than an imprint on us of the Divine light. It is therefore evident that the natural law is nothing else than the rational creature's participation of the eternal law.

Reply to Objection 1. This argument would hold, if the natural law were something different from the eternal law: whereas it is nothing but a participation thereof, as stated above.

Reply to Objection 2. Every act of reason and will in us is based on that which is according to nature, as stated above (10, 1): for every act of reasoning is based on principles that are known naturally, and every act of appetite in respect of the means is derived from the natural appetite in respect of the last end. Accordingly the first direction of our acts to their end must needs be in virtue of the natural law.

I answer that, Besides the natural and the human law it was necessary for the directing of human conduct to have a Divine law. And this for four reasons. First, because it is by law that man is directed how to perform his proper acts in view of his last end. And indeed if man were ordained to no other end than that which is proportionate to his natural faculty, there would be no need for man to have any further direction of the part of his reason, besides the natural law and human law which is derived from it. But since man is ordained to an end of eternal happiness which is inproportionate to man's natural faculty, as stated above (5, 5), therefore it was necessary that, besides the natural and the human law, man should be directed to his end by a law given by God.

Secondly, because, on account of the uncertainty of human judgment, especially on contingent and particular matters, different people form different judgments on human acts; whence also different and contrary laws result. In order, therefore, that man may know without any doubt what he ought to do and what he ought to avoid, it was necessary for man to be directed in his proper acts by a law given by God, for it is certain that such a law cannot err.

Thirdly, because man can make laws in those matters of which he is competent to judge. But man is not competent to judge of interior movements, that are hidden, but only of exterior acts which appear: and yet for the perfection of virtue it is necessary for man to conduct himself aright in both kinds of acts. Consequently human law could not sufficiently curb and direct interior acts; and it was necessary for this purpose that a Divine law should supervene.

Fourthly, because, as Augustine says (De Lib. Arb. i, 5,6), human law cannot punish or forbid all evil deeds: since while aiming at doing away with all evils, it would do away with many good things, and would hinder the advance of the common good, which is necessary for human intercourse. In order, therefore, that no evil might remain unforbidden and unpunished, it was necessary for the Divine law to supervene, whereby all sins are forbidden.

Objection 1. It would seem that the eternal law is not a sovereign type existing in God. For there is only one eternal law. But there are many types of things in the Divine mind; for Augustine says (Qq. lxxxiii, qu. 46) that God "made each thing according to its type." Therefore the eternal law does not seem to be a type existing in the Divine mind.

On the contrary, Augustine says (De Lib. Arb. i, 6) that "the eternal law is the sovereign type, to which we must always conform."

I answer that, Just as in every artificer there pre-exists a type of the things that are made by his art, so too in every governor there must pre-exist the type of the order of those things that are to be done by those who are subject to his government. And just as the type of the things yet to be made by an art is called the art or exemplar of the products of that art, so too the type in him who governs the acts of his subjects, bears the character of a law, provided the other conditions be present which we have mentioned above (90). Now God, by His wisdom, is the Creator of all things in relation to which He stands as the artificer to the products of his art, as stated in the I, 14, 8. Moreover He governs all the acts and movements that are to be found in each single creature, as was also stated in the I, 103, 5. Wherefore as the type of the Divine Wisdom, inasmuch as by It all things are created, has the character of art, exemplar or idea; so the type of Divine Wisdom, as moving all things to their due end, bears the character of law. Accordingly the eternal law is nothing else than the type of Divine Wisdom, as directing all actions and movements.

Objection 2. Further, Basil [Damascene, De Fide Orth. iv, 22 says that the conscience or "synderesis is the law of our mind"; which can only apply to the natural law. But the "synderesis" is a habit, as was shown in the I, 79, 12. Therefore the natural law is a habit.

Objection 3. Further, the natural law abides in man always, as will be shown further on (6). But man's reason, which the law regards, does not always think about the natural law. Therefore the natural law is not an act, but a habit.

On the contrary, Augustine says (De Bono Conjug. xxi) that "a habit is that whereby something is done when necessary." But such is not the natural law: since it is in infants and in the damned who cannot act by it. Therefore the natural law is not a habit.

I answer that, A thing may be called a habit in two ways. First, properly and essentially: and thus the natural law is not a habit. For it has been stated above (90, 1, ad 2) that the natural law is something appointed by reason, just as a proposition is a work of reason. Now that which a man does is not the same as that whereby he does it: for he makes a becoming speech by the habit of grammar. Since then a habit is that by which we act, a law cannot be a habit properly and essentially.

Secondly, the term habit may be applied to that which we hold by a habit: thus faith may mean that which we hold by faith. And accordingly, since the precepts of the natural law are sometimes considered by reason actually, while sometimes they are in the reason only habitually, in this way the natural law may be called a habit. Thus, in speculative matters, the indemonstrable principles are not the habit itself whereby we hold those principles, but are the principles the habit of which we possess.

Reply to Objection 2. "Synderesis" is said to be the law of our mind, because it is a habit containing the precepts of the natural law, which are the first principles of human actions.

Reply to Objection 3. This argument proves that the natural law is held habitually; and this is granted.

Objection 1. It would seem that the natural law contains, not several precepts, but one only. For law is a kind of precept, as stated above (92, 2). If therefore there were many precepts of the natural law, it would follow that there are also many natural laws.

Objection 2. Further, the natural law is consequent to human nature. But human nature, as a whole, is one; though, as to its parts, it is manifold. Therefore, either there is but one precept of the law of nature, on account of the unity of nature as a whole; or there are many, by reason of the number of parts of human nature. The result would be that even things relating to the inclination of the concupiscible faculty belong to the natural law.

Objection 3. Further, law is something pertaining to reason, as stated above (90, 1). Now reason is but one in man. Therefore there is only one precept of the natural law.

On the contrary, The precepts of the natural law in man stand in relation to practical matters, as the first principles to matters of demonstration. But there are several first indemonstrable principles. Therefore there are also several precepts of the natural law.

I answer that, As stated above (91, 3), the precepts of the natural law are to the practical reason, what the first principles of demonstrations are to the speculative reason; because both are self-evident principles. Now a thing is said to be self-evident in two ways: first, in itself; secondly, in relation to us. Any proposition is said to be self-evident in itself, if its predicate is contained in the notion of the subject: although, to one who knows not the definition of the subject, it happens that such a proposition is not self-evident. For instance, this proposition, "Man is a rational being," is, in its very nature, self-evident, since who says "man," says "a rational being": and yet to one who knows not what a man is, this proposition is not self-evident. Hence it is that, as Boethius says (De Hebdom.), certain axioms or propositions are universally self-evident to all; and such are those propositions whose terms are known to all, as, "Every whole is greater than its part," and, "Things equal to one and the same are equal to one another." But some propositions are self-evident only to the wise, who understand the meaning of the terms of such propositions: thus to one who understands that an angel is not a body, it is self-evident that an angel is not circumscriptively in a place: but this is not evident to the unlearned, for they cannot grasp it.

Now a certain order is to be found in those things that are apprehended universally. For that which, before aught else, falls under apprehension, is "being," the notion of which is included in all things whatsoever a man apprehends. Wherefore the first indemonstrable principle is that "the same thing cannot be affirmed and denied at the same time," which is based on the notion of "being" and "not-being": and on this principle all others are based, as is stated in Metaph. iv, text. 9. Now as "being" is the first thing that falls under the apprehension simply, so "good" is the first thing that falls under the apprehension of the practical reason, which is directed to action: since every agent acts for an end under the aspect of good. Consequently the first principle of practical reason is one founded on the notion of good, viz. that "good is that which all things seek after." Hence this is the first precept of law, that "good is to be done and pursued, and evil is to be avoided." All other precepts of the natural law are based upon this: so that whatever the practical reason naturally apprehends as man's good (or evil) belongs to the precepts of the natural law as something to be done or avoided.

Since, however, good has the nature of an end, and evil, the nature of a contrary, hence it is that all those things to which man has a natural inclination, are naturally apprehended by reason as being good, and consequently as objects of pursuit, and their contraries as evil, and objects of avoidance. Wherefore according to the order of natural inclinations, is the order of the precepts of the natural law. Because in man there is first of all an inclination to good in accordance with the nature which he has in common with all substances: inasmuch as every substance seeks the preservation of its own being, according to its nature: and by reason of this inclination, whatever is a means of preserving human life, and of warding off its obstacles, belongs to the natural law. Secondly, there is in man an inclination to things that pertain to him more specially, according to that nature which he has in common with other animals: and in virtue of this inclination, those things are said to belong to the natural law, "which nature has taught to all animals" [Pandect. Just. I, tit. i], such as sexual intercourse, education of offspring and so forth. Thirdly, there is in man an inclination to good, according to the nature of his reason, which nature is proper to him: thus man has a natural inclination to know the truth about God, and to live in society: and in this respect, whatever pertains to this inclination belongs to the natural law; for instance, to shun ignorance, to avoid offending those among whom one has to live, and other such things regarding the above inclination.

Reply to Objection 1. All these precepts of the law of nature have the character of one natural law, inasmuch as they flow from one first precept.

Reply to Objection 2. All the inclinations of any parts whatsoever of human nature, e.g. of the concupiscible and irascible parts, in so far as they are ruled by reason, belong to the natural law, and are reduced to one first precept, as stated above: so that the precepts of the natural law are many in themselves, but are based on one common foundation.

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. 22:37,39. 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.

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.