The Dominican Father Thomas Pegues discusses St. Thomas Aquinas’ Treatise on the Cardinal Moral Virtues (Summa Theologica II-II, 47-170), which are prudence, justice, fortitude, and temperance.
He writes: “Prudence is a principle of moral action that perfects man’s practical reason, so that in every action he dispose and order all things as it behooves, by commanding himself and those under him to do at each moment what is necessary for the perfect realization of every virtue.” Prudence is of great importance, for without prudence “there could be no virtuous act in man’s life at all.”
These are the elements which constitute prudence: memory; insight into principles of action; respect for what the wise have determined; astuteness to discover a suitable course of action; a rational application of principles; foresight regarding the substance of the act; circumspection regarding all circumstances of the act; and precaution against obstacles to the successful completion of the act.
The act proper to prudence is command. “A man is called ‘prudent’ by reason of the counsel he takes before accepting the command; but prudence proper is in the act itself of giving a command with decision.” There are four species of commanded acts: the act of command as regards oneself, one’s family, society, and the army. Accordingly, there are four species of prudence: individual, domestic, political, and military.
Individual prudence is “necessary to each individual person for the leading of a virtuous life for his own individual good.” Domestic prudence is “necessary to every member of a family, so that each, under the head of the family, concur in the common welfare of the family.” Political prudence is “necessary to the head of a society, whether an independent city or a nation, for the governing thereof.” And “there must be a proportionate prudence also in the people governed.” The prudence of the governed consists in this: “that each member of a society should strive by his correspondence to the orders of the government to further the common interests of the society.” Military prudence is “of great importance for the well-being of the society, since it is through the able commanding of the officers and the perfect discipline of the rank and file that the country defends its rights and repels the unjust invasions of an enemy.”
The gift of counsel, a gift of the Holy Spirit, corresponds to the virtue of prudence. “It is a supernatural perfection of man’s practical reason that makes him docile and ready under the action of the Holy Ghost to take counsel and to sift well everything that in life relates to salvation; . . . for even though he possess all the acquired and the infused virtues he cannot do without this gift, which helps him to make a perfect judgment and act of command, since he is for ever liable to err amidst the complexity of circumstances that accompany every human act.”
Quotations from Thomas Pegues, Catechism of the “Summa Theologica” of Saint Thomas Aquinas, trans. Aelred Whitacre (New York: Benziger, 1922).