Objection 1. It would seem that there is but one moral virtue about operations. Because the rectitude of all external operations seems to belong to justice. Now justice is but one virtue. Therefore there is but one virtue about operations.
Objection 2. Further, those operations seem to differ most, which are directed on the one side to the good of the individual, and on the other to the good of the many. But this diversity does not cause diversity among the moral virtues: for the Philosopher says (Ethic. v, 1) that legal justice, which directs human acts to the common good, does not differ, save logically, from the virtue which directs a man's actions to one man only. Therefore diversity of operations does not cause a diversity of moral virtues.
Objection 3. Further, if there are various moral virtues about various operations, diversity of moral virtues would needs follow diversity of operations. But this is clearly untrue: for it is the function of justice to establish rectitude in various kinds of commutations, and again in distributions, as is set down in Ethic. v, 2. Therefore there are not different virtues about different operations.
On the contrary, Religion is a moral virtue distinct from piety, both of which are about operations.
I answer that, All the moral virtues that are about operations agree in one general notion of justice, which is in respect of something due to another: but they differ in respect of various special notions. The reason for this is that in external operations, the order of reason is established, as we have stated (2), not according as how man is affected towards such operations, but according to the becomingness of the thing itself; from which becomingness we derive the notion of something due which is the formal aspect of justice: for, seemingly, it pertains to justice that a man give another his due. Wherefore all such virtues as are about operations, bear, in some way, the character of justice. But the thing due is not of the same kind in all these virtues: for something is due to an equal in one way, to a superior, in another way, to an inferior, in yet another; and the nature of a debt differs according as it arises from a contract, a promise, or a favor already conferred. And corresponding to these various kinds of debt there are various virtues: e.g. "Religion" whereby we pay our debt to God; "Piety," whereby we pay our debt to our parents or to our country; "Gratitude," whereby we pay our debt to our benefactors, and so forth.
Reply to Objection 1. Justice properly so called is one special virtue, whose object is the perfect due, which can be paid in the equivalent. But the name of justice is extended also to all cases in which something due is rendered: in this sense it is not as a special virtue.
Reply to Objection 2. That justice which seeks the common good is another virtue from that which is directed to the private good of an individual: wherefore common right differs from private right; and Tully (De Inv. ii) reckons as a special virtue, piety which directs man to the good of his country. But that justice which directs man to the common good is a general virtue through its act of command: since it directs all the acts of the virtues to its own end, viz. the common good. And the virtues, in so far as they are commanded by that justice, receive the name of justice: so that virtue does not differ, save logically, from legal justice; just as there is only a logical difference between a virtue that is active of itself, and a virtue that is active through the command of another virtue.
Reply to Objection 3. There is the same kind of due in all the operations belonging to special justice. Consequently, there is the same virtue of justice, especially in regard to commutations. For it may be that distributive justice is of another species from commutative justice; but about this we shall inquire later on (II-II, 61, 1).
Source: Summa Theologica (New Advent)