Mercy is a virtue influencing one’s will to have compassion for, and, if possible, to alleviate another’s misfortune. St. Thomas Aquinas teaches that, although mercy is as it were the spontaneous product of charity, it is a special virtue adequately distinguishable from this charity. In fact the Scholastics consider it to be related to justice mainly because, like justice, it controls relations between distinct persons.
Mercy sees misery in another person, and inflames a desire to alleviate that misery. Since misery can afflict both body and soul, it is customary to enumerate both corporal and spiritual works of mercy. The traditional enumeration of the corporal and works of mercy, respectively, is as follows:
To feed the hungry;
To give drink to the thirsty;
To clothe the naked;
To shelter the homeless;
To visit the sick;
To visit those in prison;
To bury the dead.
To instruct the ignorant;
To counsel the doubtful;
To admonish sinners;
To bear wrongs patiently;
To forgive offences willingly;
To comfort the afflicted;
To pray for the living and the dead.