Article III. On The Potential Parts Of Justice

73. As has already often been said, the potential parts of some cardinal virtue are called virtues which indeed agree with it in its object considered generally, but in some way fall short of the perfect ratio of it. But the function of justice is to render to another what is owed, and indeed according to equality. Therefore in two ways can some virtue existing toward another fall short of the ratio of justice: 1. insofar as it falls short of the ratio of the equal; 2. insofar as it falls short of the ratio of strict debt.

On account of the first deficiency, namely in rendering strict equality, three virtues are joined to justice as potential parts, namely religion, piety, observance. 1. For religion is the virtue rendering due worship to God, but man is never able to worship God as He deserves. 2. Piety is the virtue inclining one to render due honor and love to parents. But according to equality there cannot be recompensed to parents what is owed to them by children. 3. Observance is the virtue inclining one to offer due reverence to men excelling in great virtue and dignity. Moreover great virtue also is not recompensed according to an equal reward on this earth.

On account of the other deficiency, namely of strict debt, six virtues are joined to justice: namely 1. veracity or truth, which is the virtue inclining one always to say the true and never to lie. To this virtue are reduced a) faith or fidelity in promises; b) simplicity, by which someone exteriorly shows himself in words and deeds to be such as he is interiorly. To veracity are opposed lying, infidelity, hypocrisy, simulation, and generally all those things concerning which there is discussion in the eighth precept of the Decalogue. 2. Gratitude or grace, which is the virtue inclining one at least in some way to compensate a benefit received. 3. Vindication, which is the virtue avenging injuries committed. Very closely related to vindication is the virtue of penance, by which one tries to repair injuries inflicted upon God by sinning. 4. Liberality, which moderates the love of money, so that we may willingly expend it for our own utility and that of our neighbor and for the honor of God. 5. Affability, which makes conversation with one's neighbor pleasing and fitting. 6. Equity or epikeia, which inclines one from just causes to pass over the words of the law and rather to act according to the presumed intention of the legislator.¹⁴⁸ - As is easily clear to one considering the matter, in all these six enumerated virtues there is not so strict an obligation of debt as in justice, and consequently all are deservedly enumerated as potential parts of the cardinal virtue of justice. Concerning the individual ones there will be discussion below.

¹⁴⁸ Epikeia is taken in diverse senses, as will be said below, n. 617. Cf. also I, n. 231 sqq.