paragraph — Noldin, Summa of Moral Theology
§ 1. On Mercy
86. On the nature of mercy. 1. An act of charity toward the neighbor constituted in misery is called mercy. A benefit furnished to a neighbor constituted in misery is a work of mercy, or alms taken generally.
Mercy is a moral virtue by which man, from commiseration, is inclined to relieve another's misery. Therefore it differs from charity in this, that charity universally wills and procures good for the neighbor from benevolence, but mercy wills and procures it for him who is in misery from compassion. For the misery of the neighbor naturally moves one to compassion, and compassion to relieving misery.
The material object of mercy is the evil or misery of another (sickness, ignorance, poverty, sin, etc.), which the merciful person tries to remove. The formal object is the moral goodness which shines forth in removing another's evil from compassion.
Note. The Christian religion especially has taught us the virtue of mercy. For although the law of nature demands it, nevertheless its notion among the gentiles had been obscured and its exercise so neglected that Plato wanted the poor to be banished from the republic, and Seneca thought mercy a vice of the soul. To these Christ the Lord opposed His own mind, saying: I have compassion on the multitude;1 Come to Me all who labor and are burdened.2
1 Mark 8:2.
2 Matt. 11:28. Cf. A. Weiss, Apologie, Freiburg: Herder, 1897, III, p. 807.
87. On the precept of mercy. a. From the universal precept of charity it follows that each one of himself is bound under grave obligation to succor a neighbor constituted in misery, if he morally can (n. 54): for he who refuses to relieve another's misery does not truly love the neighbor.
Someone can be obliged to succor the neighbor from common charity, by which all, having the same human nature, ought to do good to one another; or from special charity (piety), by which those who are joined by a special reason, as blood relatives, are bound to succor one another; or from charity and justice, by which those who by office have care of others are bound to aid them. Moreover, as long as there are those who are bound to succor from justice or from special charity, and are also believed to be able and willing to succor, others are not bound from common charity; but when those fail, these are bound.
b. Although we are bound to furnish to the neighbor who is in want the good which he needs, or to avert from him the evil which threatens him, whether it is bodily or spiritual, nevertheless none are bound to inquire into the needy except those upon whom the care of others rests by office: for it belongs to the needy themselves to set forth their necessity.
Yet one who reasonably doubts concerning the extreme necessity of someone is bound to inquire into the truth; and if, after inquiry has been made, the doubt remains, there is no obligation of aiding.
88. Works of mercy. The misery of the neighbor can be bodily or spiritual; wherefore some works of mercy are bodily, others spiritual. The bodily works are numbered as seven: to feed the hungry, to give drink to the thirsty, to clothe the naked, to receive travelers, to visit the sick, to redeem captives, to bury the dead. Likewise the spiritual works are numbered as seven: to teach the ignorant, to give counsel to the doubtful, to console the sorrowful, to correct sinners, to forgive those who offend, to bear with the troublesome, to pray for the living and the dead. Here we must treat only of two: of alms strictly so called, by which name the bodily works of mercy are designated, and of fraternal correction, which alone among the spiritual works of mercy presents a special difficulty.