(b) The virtue of mercy, which is a rational inclination of the will to relieve the suffering or misfortune of others, is held to be greater than justice, because to relieve the distress of the community or of an individual indicates greater perfection than to pay merely what is due to another.
1718. Virtues may be compared, not only from the viewpoint of the objective excellence which they have from their own natures (whereby they are unequal and rank according to the greatness of their objects), but also from the viewpoint of the subjective participation of them in the souls of their possessors.
(a) In a certain sense, all the virtues are equal in their possessor, since all of them alike are related to charity as their perfection (see 1118), and all of them increase or diminish in like proportions with the growth or decline of grace, which is their root (see 745).
(b) In a certain sense, too, the rank of the virtues may depart from the order of the dignity of their objects. For the facility and promptitude of exercise of an infused virtue does not depend formally on the infused virtue itself, but on subjective conditions, such as natural inclination or custom, or on a special gift of God (see 135, 136); and hence it may happen that a saint shows greater excellence and enjoys greater renown in an inferior than in a superior virtue. Thus, Abraham was singular in faith, Moses in meekness, Josue in bravery, David in fervor and devotion (Ecclus., xlv-xlviii), and St. Joseph is praised as “a just man” (Matt., i. 19).
1719. Injustice.—Just as the word “justice” is taken in a wide sense for holiness or the collection of all the virtues, and in a strict sense for a special cardinal virtue, so likewise the word “injustice” is taken widely as a synonym for any transgression, iniquity, or sin (“He sendeth rain upon the just and the unjust,” Matt., v. 45), but strictly for violation of the special virtue of justice (“Hear what the unjust judge saith,” Luke, xviii. 6). It is of this latter injustice that we now speak.
1720. Species of Injustice.—Injustice is of two kinds. (a) Legal injustice is a special vice that moves one to despise the common good or to act against it intentionally. Thus, if one steals or overeats merely to gratify a passion for money or for food, there is a certain condition of legal injustice, inasmuch as one violates a law; but if one does these things also or solely to injure the common good, there is a special sin of legal injustice, to be declared in confession. (b) Particular injustice is a special vice against the private good of others that moves one to seek for more than is one’s share, or to desire more of the benefits and less of the burdens than equality appoints. Examples: To sell above the just price or buy below the just price (commutative injustice); to show favoritism in the distribution of public offices or burdens, as when a person in authority showers public benefits on his unworthy relatives or friends, and overburdens with taxes those who are not his friends (distributive injustice).
1721. The Theological Species of Legal and Particular Injustice.—(a) From its nature injustice is a mortal sin, for it is an attack on a very great good, namely, the peace and security of society; the very foundations of orderly community life are shaken when injustice is done either to common or to private rights. Moreover, acts of injustice (unlike sins of mere passion), if the matter is serious, offend against charity, the life of the soul; for charity “envieth not, dealeth not perversely” (I Cor., xiii. 4); while injustice injures the neighbor and leads to hatred, quarrels, and separations. Hence, the Apostle says of injustice: “Do not err: neither adulterers, nor thieves, nor covetous, nor extortioners, shall possess the kingdom of God” (I Cor., vi. 10); and Our Lord, speaking of justice, says: “If you would enter into life, keep the commandments” (Matt, xix. 18).
(b) From want of sufficient advertence in the subject (see 173 sqq.), or from smallness of matter in the object (see 172), a sin of injustice may be only venial. Thus, if one takes money that belongs to another on account of vincible ignorance due to slight negligence, or if one takes only a small amount that does no serious injury, the injustice is venial.
1722. Rule for Determining the Gravity of Sins of Injustice.—The rule for judging whether the matter of a sin of injustice is great or small, is the quantity of injury it inflicts, or the degree of reasonable unwillingness of the offended person to suffer the injustice; for sins against the neighbor are culpable precisely on account of and in proportion to the harm they do to others. Hence, since every injustice offends either the public or private good, or both, the following acts of injustice are gravely sinful:
(a) mortal sin is committed when injury is done to a private right in a matter of such great moment that the person offended is reasonably and gravely unwilling to sanction the injustice (e.g., cases of calumny, adultery, incendiarism). But if the injury itself is small and the party offended is nevertheless gravely unwilling to suffer it, only venial sin is committed against justice, but there may be a mortal sin done against charity, as when one steals a worthless trinket, knowing that the owner is so unreasonably attached to it that the loss will almost break his heart or will provoke in him violent anger, profanity, etc.;