Summa Th. II-II EN Qu.55 a.2
Objection: 1. It would seem that prudence of the flesh is a mortal sin. For it is a mortal sin to rebel against the Divine law, since this implies contempt of God. Now "the prudence [Douay: 'wisdom'] of the flesh . . . is not subject to the law of God" (Rm 8,7). Therefore prudence of the flesh is a mortal sin.
2. Further, every sin against the Holy Ghost is a mortal sin. Now prudence of the flesh seems to be a sin against the Holy Ghost, for "it cannot be subject to the law of God" (Rm 8,7), and so it seems to be an unpardonable sin, which is proper to the sin against the Holy Ghost. Therefore prudence of the flesh is a mortal sin.
3. Further, the greatest evil is opposed to the greatest good, as stated in Ethic. viii, 10. Now prudence of the flesh is opposed to that prudence which is the chief of the moral virtues. Therefore prudence of the flesh is chief among mortal sins, so that it is itself a mortal sin.
On the contrary That which diminishes a sin has not of itself the nature of a mortal sin. Now the thoughtful quest of things pertaining to the care of the flesh, which seems to pertain to carnal prudence, diminishes sin [*Cf. Pr 6,30]. Therefore prudence of the flesh has not of itself the nature of a mortal sin.
I answer that As stated above (Question , Article , ad 1; Article ), a man is said to be prudent in two ways. First, simply, i.e. in relation to the end of life as a whole. Secondly, relatively, i.e. in relation to some particular end; thus a man is said to be prudent in business or something else of the kind. Accordingly if prudence of the flesh be taken as corresponding to prudence in its absolute signification, so that a man place the last end of his whole life in the care of the flesh, it is a mortal sin, because he turns away from God by so doing, since he cannot have several last ends, as stated above (I-II 1,5).If, on the other hand, prudence of the flesh be taken as corresponding to particular prudence, it is a venial sin. For it happens sometimes that a man has an inordinate affection for some pleasure of the flesh, without turning away from God by a mortal sin; in which case he does not place the end of his whole life in carnal pleasure. To apply oneself to obtain this pleasure is a venial sin and pertains to prudence of the flesh. But if a man actually refers the care of the flesh to a good end, as when one is careful about one's food in order to sustain one's body, this is no longer prudence of the flesh, because then one uses the care of the flesh as a means to an end.
Reply to Objection: 1. The Apostle is speaking of that carnal prudence whereby a man places the end of his whole life in the goods of the flesh, and this is a mortal sin.
2. Prudence of the flesh does not imply a sin against the Holy Ghost. For when it is stated that "it cannot be subject to the law of God," this does not mean that he who has prudence of the flesh, cannot be converted and submit to the law of God, but that carnal prudence itself cannot be subject to God's law, even as neither can injustice be just, nor heat cold, although that which is hot may become cold.
3. Every sin is opposed to prudence, just as prudence is shared by every virtue. But it does not follow that every sin opposed to prudence is most grave, but only when it is opposed to prudence in some very grave matter.
Objection: 1. It would seem that craftiness is not a special sin. For the words of Holy Writ do not induce anyone to sin; and yet they induce us to be crafty, according to Pr 1,4, "To give craftiness [Douay: 'subtlety'] to little ones." Therefore craftiness is not a sin.
2. Further, it is written (Pr 13,16): "The crafty [Douay: 'prudent'] man doth all things with counsel." Therefore, he does so either for a good or for an evil end. If for a good end, there is no sin seemingly, and if for an evil end, it would seem to pertain to carnal or worldly prudence. Therefore craftiness is not a special sin distinct from prudence of the flesh.
3. Further, Gregory expounding the words of Jb 12, "The simplicity of the just man is laughed to scorn," says (Moral. x, 29): "The wisdom of this world is to hide one's thoughts by artifice, to conceal one's meaning by words, to represent error as truth, to make out the truth to be false," and further on he adds: "This prudence is acquired by the young, it is learnt at a price by children." Now the above things seem to belong to craftiness. Therefore craftiness is not distinct from carnal or worldly prudence, and consequently it seems not to be a special sin.
On the contrary The Apostle says (2Co 4,2): "We renounce the hidden things of dishonesty, not walking in craftiness, nor adulterating the word of God." Therefore craftiness is a sin.
I answer that Prudence is "right reason applied to action," just as science is "right reason applied to knowledge." In speculative matters one may sin against rectitude of knowledge in two ways: in one way when the reason is led to a false conclusion that appears to be true; in another way when the reason proceeds from false premises, that appear to be true, either to a true or to a false conclusion. Even so a sin may be against prudence, through having some resemblance thereto, in two ways. First, when the purpose of the reason is directed to an end which is good not in truth but in appearance, and this pertains to prudence of the flesh; secondly, when, in order to obtain a certain end, whether good or evil, a man uses means that are not true but fictitious and counterfeit, and this belongs to the sin of craftiness. This is consequently a sin opposed to prudence, and distinct from prudence of the flesh.
Reply to Objection: 1. As Augustine observes (Contra Julian. iv, 3) just as prudence is sometimes improperly taken in a bad sense, so is craftiness sometimes taken in a good sense, and this on account of their mutual resemblance. Properly speaking, however, craftiness is taken in a bad sense, as the Philosopher states in Ethic. vi, 12.
2. Craftiness can take counsel both for a good end and for an evil end: nor should a good end be pursued by means that are false and counterfeit but by such as are true. Hence craftiness is a sin if it be directed to a good end.
3. Under "worldly prudence" Gregory included everything that can pertain to false prudence, so that it comprises craftiness also.
Objection: 1. It would seem that guile is not a sin pertaining to craftiness. For sin, especially mortal, has no place in perfect men. Yet a certain guile is to be found in them, according to 2Co 12,16, "Being crafty I caught you by guile." Therefore guile is not always a sin.
2. Further, guile seems to pertain chiefly to the tongue, according to Ps 5,11, "They dealt deceitfully with their tongues." Now craftiness like prudence is in the very act of reason. Therefore guile does not pertain to craftiness.
3. Further, it is written (Pr 12,20): "Guile [Douay: 'Deceit'] is in the heart of them that think evil things." But the thought of evil things does not always pertain to craftiness. Therefore guile does not seem to belong to craftiness.
On the contrary Craftiness aims at lying in wait, according to Ep 4,14, "By cunning craftiness by which they lie in wait to deceive": and guile aims at this also. Therefore guile pertains to craftiness.
I answer that As stated above (Article ), it belongs to craftiness to adopt ways that are not true but counterfeit and apparently true, in order to attain some end either good or evil. Now the adopting of such ways may be subjected to a twofold consideration; first, as regards the process of thinking them out, and this belongs properly to craftiness, even as thinking out right ways to a due end belongs to prudence. Secondly the adopting of such like ways may be considered with regard to their actual execution, and in this way it belongs to guile. Hence guile denotes a certain execution of craftiness, and accordingly belongs thereto.
Reply to Objection: 1. Just as craftiness is taken properly in a bad sense, and improperly in a good sense, so too is guile which is the execution of craftiness.
2. The execution of craftiness with the purpose of deceiving, is effected first and foremost by words, which hold the chief place among those signs whereby a man signifies something to another man, as Augustine states (De Doctr. Christ. ii, 3), hence guile is ascribed chiefly to speech. Yet guile may happen also in deeds, according to Ps 104,25, "And to deal deceitfully with his servants." Guile is also in the heart, according to Si 19,23, "His interior is full of deceit," but this is to devise deceits, according to Ps 37,13: "They studied deceits all the day long."
3. Whoever purposes to do some evil deed, must needs devise certain ways of attaining his purpose, and for the most part he devises deceitful ways, whereby the more easily to obtain his end. Nevertheless it happens sometimes that evil is done openly and by violence without craftiness and guile; but as this is more difficult, it is of less frequent occurrence.
Objection: 1. It would seem that fraud does not pertain to craftiness. For a man does not deserve praise if he allows himself to be deceived, which is the object of craftiness; and yet a man deserves praise for allowing himself to be defrauded, according to 1Co 6,1, "Why do you not rather suffer yourselves to be defrauded?" Therefore fraud does not belong to craftiness.
2. Further, fraud seems to consist in unlawfully taking or receiving external things, for it is written (Ac 5,1) that "a certain man named Ananias with Saphira his wife, sold a piece of land, and by fraud kept back part of the price of the land." Now it pertains to injustice or illiberality to take possession of or retain external things unjustly. Therefore fraud does not belong to craftiness which is opposed to prudence.
3. Further, no man employs craftiness against himself. But the frauds of some are against themselves, for it is written (Pr 1,18) concerning some "that they practice frauds [Douay: 'deceits'] against their own souls." Therefore fraud does not belong to craftiness.
On the contrary The object of fraud is to deceive, according to Jb 13,9, "Shall he be deceived as a man, with your fraudulent [Douay: 'deceitful'] dealings?" Now craftiness is directed to the same object. Therefore fraud pertains to craftiness.
I answer that Just as "guile" consists in the execution of craftiness, so also does "fraud." But they seem to differ in the fact that "guile" belongs in general to the execution of craftiness, whether this be effected by words, or by deeds, whereas "fraud" belongs more properly to the execution of craftiness by deeds.
Reply to Objection: 1. The Apostle does not counsel the faithful to be deceived in their knowledge, but to bear patiently the effect of being deceived, and to endure wrongs inflicted on them by fraud.
2. The execution of craftiness may be carried out by another vice, just as the execution of prudence by the virtues: and accordingly nothing hinders fraud from pertaining to covetousness or illiberality.
3. Those who commit frauds, do not design anything against themselves or their own souls; it is through God's just judgment that what they plot against others, recoils on themselves, according to Ps 7,16, "He is fallen into the hole he made."
Objection: 1. It would seem lawful to be solicitous about temporal matters. Because a superior should be solicitous for his subjects, according to Rm 12,8, "He that ruleth, with solicitude." Now according to the Divine ordering, man is placed over temporal things, according to Ps 8,8, "Thou hast subjected all things under his feet," etc. Therefore man should be solicitous about temporal things.
2. Further, everyone is solicitous about the end for which he works. Now it is lawful for a man to work for the temporal things whereby he sustains life, wherefore the Apostle says (2Th 3,10): "If any man will not work, neither let him eat." Therefore it is lawful to be solicitous about temporal things.
3. Further, solicitude about works of mercy is praiseworthy, according to 2Tm 1,17, "When he was come to Rome, he carefully sought me." Now solicitude about temporal things is sometimes connected with works of mercy; for instance, when a man is solicitous to watch over the interests of orphans and poor persons. Therefore solicitude about temporal things is not unlawful.
On the contrary Our Lord said (Mt 6,31): "Be not solicitous . . . saying, What shall we eat, or what shall we drink, or wherewith shall we be clothed?" And yet such things are very necessary.
I answer that Solicitude denotes an earnest endeavor to obtain something. Now it is evident that the endeavor is more earnest when there is fear of failure, so that there is less solicitude when success is assured. Accordingly solicitude about temporal things may be unlawful in three ways. First on the part of the object of solicitude; that is, if we seek temporal things as an end. Hence Augustine says (De Operibus Monach. xxvi): "When Our Lord said: 'Be not solicitous,' etc. . . . He intended to forbid them either to make such things their end, or for the sake of these things to do whatever they were commanded to do in preaching the Gospel." Secondly, solicitude about temporal things may be unlawful, through too much earnestness in endeavoring to obtain temporal things, the result being that a man is drawn away from spiritual things which ought to be the chief object of his search, wherefore it is written (Mt 13,22) that "the care of this world . . . chokes up the word." Thirdly, through over much fear, when, to wit, a man fears to lack necessary things if he do what he ought to do. Now our Lord gives three motives for laying aside this fear. First, on account of the yet greater favors bestowed by God on man, independently of his solicitude, viz. his body and soul (Mt 6,26); secondly, on account of the care with which God watches over animals and plants without the assistance of man, according to the requirements of their nature; thirdly, because of Divine providence, through ignorance of which the gentiles are solicitous in seeking temporal goods before all others. Consequently He concludes that we should be solicitous most of all about spiritual goods, hoping that temporal goods also may be granted us according to our needs, if we do what we ought to do.
Reply to Objection: 1. Temporal goods are subjected to man that he may use them according to his needs, not that he may place his end in them and be over solicitous about them.
2. The solicitude of a man who gains his bread by bodily labor is not superfluous but proportionate; hence Jerome says on Mt 6,31, "Be not solicitous," that "labor is necessary, but solicitude must be banished," namely superfluous solicitude which unsettles the mind.
3. In the works of mercy solicitude about temporal things is directed to charity as its end, wherefore it is not unlawful, unless it be superfluous.
Objection: 1. It would seem that we should be solicitous about the future. For it is written (Pr 6,6-8): "Go to the ant, O sluggard, and consider her ways and learn wisdom; which, although she hath no guide, nor master . . . provideth her meat for herself in the summer, and gathereth her food in the harvest." Now this is to be solicitous about the future. Therefore solicitude about the future is praiseworthy.
2. Further, solicitude pertains to prudence. But prudence is chiefly about the future, since its principal part is "foresight of future things," as stated above (Question , Article , ad 1). Therefore it is virtuous to be solicitous about the future.
3. Further, whoever puts something by that he may keep it for the morrow, is solicitous about the future. Now we read (Jn 12,6) that Christ had a bag for keeping things in, which Judas carried, and (Ac 4,34-37) that the Apostles kept the price of the land, which had been laid at their feet. Therefore it is lawful to be solicitous about the future.
On the contrary Our Lord said (Mt 6,34): "Be not . . . solicitous for tomorrow"; where "tomorrow" stands for the future, as Jerome says in his commentary on this passage.
I answer that No work can be virtuous, unless it be vested with its due circumstances, and among these is the due time, according to Qo 8,6, "There is a time and opportunity for every business"; which applies not only to external deeds but also to internal solicitude. For every time has its own fitting proper solicitude; thus solicitude about the crops belongs to the summer time, and solicitude about the vintage to the time of autumn. Accordingly if a man were solicitous about the vintage during the summer, he would be needlessly forestalling the solicitude belonging to a future time. Hence Our Lord forbids such like excessive solicitude, saying: "Be . . . not solicitous for tomorrow," wherefore He adds, "for the morrow will be solicitous for itself," that is to say, the morrow will have its own solicitude, which will be burden enough for the soul. This is what He means by adding: "Sufficient for the day is the evil thereof," namely, the burden of solicitude.
Reply to Objection: 1. The ant is solicitous at a befitting time, and it is this that is proposed for our example.
2. Due foresight of the future belongs to prudence. But it would be an inordinate foresight or solicitude about the future, if a man were to seek temporal things, to which the terms "past" and "future" apply, as ends, or if he were to seek them in excess of the needs of the present life, or if he were to forestall the time for solicitude.
3. As Augustine says (De Serm. Dom. in Monte ii, 17), "when we see a servant of God taking thought lest he lack these needful things, we must not judge him to be solicitous for the morrow, since even Our Lord deigned for our example to have a purse, and we read in the Acts of the Apostles that they procured the necessary means of livelihood in view of the future on account of a threatened famine. Hence Our Lord does not condemn those who according to human custom, provide themselves with such things, but those who oppose themselves to God for the sake of these things."
Objection: 1. It would seem that these vices do not arise from covetousness. As stated above (Question , Article ) lust is the chief cause of lack of rectitude in the reason. Now these vices are opposed to right reason, i.e. to prudence. Therefore they arise chiefly from lust; especially since the Philosopher says (Ethic. vii, 6) that "Venus is full of guile and her girdle is many colored" and that "he who is incontinent in desire acts with cunning."
2. Further, these vices bear a certain resemblance to prudence, as stated above (Question , Article ). Now, since prudence is in the reason, the more spiritual vices seem to be more akin thereto, such as pride and vainglory. Therefore the aforesaid vices seem to arise from pride rather than from covetousness.
3. Further, men make use of stratagems not only in laying hold of other people's goods, but also in plotting murders, the former of which pertains to covetousness, and the latter to anger. Now the use of stratagems pertains to craftiness, guile, and fraud. Therefore the aforesaid vices arise not only from covetousness, but also from anger.
On the contrary Gregory (Moral. xxxi, 45) states that fraud is a daughter of covetousness.
I answer that As stated above (Article ; Question , Article ), carnal prudence and craftiness, as well as guile and fraud, bear a certain resemblance to prudence in some kind of use of the reason. Now among all the moral virtues it is justice wherein the use of right reason appears chiefly, for justice is in the rational appetite. Hence the undue use of reason appears chiefly in the vices opposed to justice, the chief of which is covetousness. Therefore the aforesaid vices arise chiefly from covetousness.
Reply to Objection: 1. On account of the vehemence of pleasure and of concupiscence, lust entirely suppresses the reason from exercising its act: whereas in the aforesaid vices there is some use of reason, albeit inordinate. Hence these vices do not arise directly from lust. When the Philosopher says that "Venus is full of guile," he is referring to a certain resemblance, in so far as she carries man away suddenly, just as he is moved in deceitful actions, yet not by means of craftiness but rather by the vehemence of concupiscence and pleasure; wherefore he adds that "Venus doth cozen the wits of the wisest man" [*Cf. Iliad xiv, 214-217].
2. To do anything by stratagem seems to be due to pusillanimity: because a magnanimous man wishes to act openly, as the Philosopher says (Ethic. iv, 3). Wherefore, as pride resembles or apes magnanimity, it follows that the aforesaid vices which make use of fraud and guile, do not arise directly from pride, but rather from covetousness, which seeks its own profit and sets little by excellence.
3. Anger's movement is sudden, hence it acts with precipitation, and without counsel, contrary to the use of the aforesaid vices, though these use counsel inordinately. That men use stratagems in plotting murders, arises not from anger but rather from hatred, because the angry man desires to harm manifestly, as the Philosopher states (Rhet. ii, 2,3) [*Cf. Ethic. vii, 6].
We must now consider the precepts relating to prudence, under which head there are two points of inquiry:
(1) The precepts of prudence;
(2) The precepts relating to the opposite vices.
Objection: 1. It would seem that the precepts of the decalogue should have included a precept of prudence. For the chief precepts should include a precept of the chief virtue. Now the chief precepts are those of the decalogue. Since then prudence is the chief of the moral virtues, it seems that the precepts of the decalogue should have included a precept of prudence.
2. Further, the teaching of the Gospel contains the Law especially with regard to the precepts of the decalogue. Now the teaching of the Gospel contains a precept of prudence (Mt 10,16): "Be ye . . . prudent [Douay: 'wise'] as serpents." Therefore the precepts of the decalogue should have included a precept of prudence.
3. Further, the other lessons of the Old Testament are directed to the precepts of the decalogue: wherefore it is written (Malach. 4:4): "Remember the law of Moses My servant, which I commanded him in Horeb." Now the other lessons of the Old Testament include precepts of prudence; for instance (Pr 3,5): "Lean not upon thy own prudence"; and further on (Pr 4,25): "Let thine eyelids go before thy steps." Therefore the Law also should have contained a precept of prudence, especially among the precepts of the decalogue.
On the contrary The contrary however appears to anyone who goes through the precepts of the decalogue.
I answer that As stated above (I-II 100,3 I-II 100,5, ad 1) when we were treating of precepts, the commandments of the decalogue being given to the whole people, are a matter of common knowledge to all, as coming under the purview of natural reason. Now foremost among the things dictated by natural reason are the ends of human life, which are to the practical order what naturally known principles are to the speculative order, as shown above (Question , Article ). Now prudence is not about the end, but about the means, as stated above (Question , Article ). Hence it was not fitting that the precepts of the decalogue should include a precept relating directly to prudence. And yet all the precepts of the decalogue are related to prudence, in so far as it directs all virtuous acts.
Reply to Objection: 1. Although prudence is simply foremost among all the moral virtues, yet justice, more than any other virtue, regards its object under the aspect of something due, which is a necessary condition for a precept, as stated above (Question , Article ; I-II 99,1 I-II 99,5). Hence it behooved the chief precepts of the Law, which are those of the decalogue, to refer to justice rather than to prudence.
2. The teaching of the Gospel is the doctrine of perfection. Therefore it needed to instruct man perfectly in all matters relating to right conduct, whether ends or means: wherefore it behooved the Gospel teaching to contain precepts also of prudence.
3. Just as the rest of the teaching of the Old Testament is directed to the precepts of the decalogue as its end, so it behooved man to be instructed by the subsequent lessons of the Old Testament about the act of prudence which is directed to the means.
Objection: 1. It would seem that the prohibitive precepts relating to the vices opposed to prudence are unfittingly propounded in the Old Law. For such vices as imprudence and its parts which are directly opposed to prudence are not less opposed thereto, than those which bear a certain resemblance to prudence, such as craftiness and vices connected with it. Now the latter vices are forbidden in the Law: for it is written (Lv 19,13): "Thou shalt not calumniate thy neighbor," and (Dt 25,13): "Thou shalt not have divers weights in thy bag, a greater and a less." Therefore there should have also been prohibitive precepts about the vices directly opposed to prudence.
2. Further, there is room for fraud in other things than in buying and selling. Therefore the Law unfittingly forbade fraud solely in buying and selling.
3. Further, there is the same reason for prescribing an act of virtue as for prohibiting the act of a contrary vice. But acts of prudence are not prescribed in the Law. Therefore neither should any contrary vices have been forbidden in the Law.
On the contrary The contrary, however, appears from the precepts of the Law which are quoted in the first objection.
I answer that As stated above (Article ), justice, above all, regards the aspect of something due, which is a necessary condition for a precept, because justice tends to render that which is due to another, as we shall state further on (Question , Article ). Now craftiness, as to its execution, is committed chiefly in matters of justice, as stated above (Question , Article ): and so it was fitting that the Law should contain precepts forbidding the execution of craftiness, in so far as this pertains to injustice, as when a man uses guile and fraud in calumniating another or in stealing his goods.
Reply to Objection: 1. Those vices that are manifestly opposed to prudence, do not pertain to injustice in the same way as the execution of craftiness, and so they are not forbidden in the Law, as fraud and guile are, which latter pertain to injustice
2. All guile and fraud committed in matters of injustice, can be understood to be forbidden in the prohibition of calumny (Lv 19,13). Yet fraud and guile are wont to be practiced chiefly in buying and selling, according to Si 26,28, "A huckster shall not be justified from the sins of the lips": and it is for this reason that the Law contained a special precept forbidding fraudulent buying and selling.
3. All the precepts of the Law that relate to acts of justice pertain to the execution of prudence, even as the precepts prohibitive of stealing, calumny and fraudulent selling pertain to the execution of craftiness.
After considering prudence we must in due sequence consider justice, the consideration of which will be fourfold:
(1) Of justice;
(2) Of its parts;
(3) Of the corresponding gift;
(4) Of the precepts relating to justice.
Four points will have to be considered about justice: (1) Right; (2) Justice itself; (3) Injustice; (4) Judgment.
Under the first head there are four points of inquiry:
(1) Whether right is the object of justice?
(2) Whether right is fittingly divided into natural and positive right?
(3) Whether the right of nations is the same as natural right?
(4) Whether right of dominion and paternal right are distinct species?
Objection: 1. It would seem that right is not the object of justice. For the jurist Celsus says [*Digest. i, 1; De Just. et Jure 1] that "right is the art of goodness and equality." Now art is not the object of justice, but is by itself an intellectual virtue. Therefore right is not the object of justice.
2. Further, "Law," according to Isidore (Etym. v, 3), "is a kind of right." Now law is the object not of justice but of prudence, wherefore the Philosopher [*Ethic. vi, 8] reckons "legislative" as one of the parts of prudence. Therefore right is not the object of justice.
3. Further, justice, before all, subjects man to God: for Augustine says (De Moribus Eccl. xv) that "justice is love serving God alone, and consequently governing aright all things subject to man." Now right [jus] does not pertain to Divine things, but only to human affairs, for Isidore says (Etym. v, 2) that "'fas' is the Divine law, and 'jus,' the human law." Therefore right is not the object of justice.
On the contrary Isidore says (Etym. v, 2) that "'jus' [right] is so called because it is just." Now the "just" is the object of justice, for the Philosopher declares (Ethic. v, 1) that "all are agreed in giving the name of justice to the habit which makes men capable of doing just actions."
I answer that It is proper to justice, as compared with the other virtues, to direct man in his relations with others: because it denotes a kind of equality, as its very name implies; indeed we are wont to say that things are adjusted when they are made equal, for equality is in reference of one thing to some other. On the other hand the other virtues perfect man in those matters only which befit him in relation to himself. Accordingly that which is right in the works of the other virtues, and to which the intention of the virtue tends as to its proper object, depends on its relation to the agent only, whereas the right in a work of justice, besides its relation to the agent, is set up by its relation to others. Because a man's work is said to be just when it is related to some other by way of some kind of equality, for instance the payment of the wage due for a service rendered. And so a thing is said to be just, as having the rectitude of justice, when it is the term of an act of justice, without taking into account the way in which it is done by the agent: whereas in the other virtues nothing is declared to be right unless it is done in a certain way by the agent. For this reason justice has its own special proper object over and above the other virtues, and this object is called the just, which is the same as "right." Hence it is evident that right is the object of justice.
Reply to Objection: 1. It is usual for words to be distorted from their original signification so as to mean something else: thus the word "medicine" was first employed to signify a remedy used for curing a sick person, and then it was drawn to signify the art by which this is done. In like manner the word "jus" [right] was first of all used to denote the just thing itself, but afterwards it was transferred to designate the art whereby it is known what is just, and further to denote the place where justice is administered, thus a man is said to appear "in jure" [*In English we speak of a court of law, a barrister at law, etc.], and yet further, we say even that a man, who has the office of exercising justice, administers the jus even if his sentence be unjust.
2. Just as there pre-exists in the mind of the craftsman an expression of the things to be made externally by his craft, which expression is called the rule of his craft, so too there pre-exists in the mind an expression of the particular just work which the reason determines, and which is a kind of rule of prudence. If this rule be expressed in writing it is called a "law," which according to Isidore (Etym. v, 1) is "a written decree": and so law is not the same as right, but an expression of right.
3. Since justice implies equality, and since we cannot offer God an equal return, it follows that we cannot make Him a perfectly just repayment. For this reason the Divine law is not properly called "jus" but "fas," because, to wit, God is satisfied if we accomplish what we can. Nevertheless justice tends to make man repay God as much as he can, by subjecting his mind to Him entirely.
Summa Th. II-II EN Qu.55 a.2