Justice

Of the three remaining divisions, the most extensive in its application is the principle by which society and what we may call its common bonds are maintained. Of this again there are two divisions—justice, in which is the crowning glory of the virtues and on the basis of which men are called good men; and, close akin to justice, charity, which may also be called kindness or generosity.

The first office of justice is to keep one man from doing harm to another, unless provoked by wrong; and the next is to lead men to use common possessions for the common interests, private property for their own.

There is, however, no such thing as private ownership established by nature, but property becomes private either through long occupancy (as in the case of those who long ago settled in unoccupied territory) or through conquest (as in the case of those who took it in war) or by due process of law, bargain, or purchase, or by allotment. On this principle the lands of Arpinum are said to belong to the Arpinates, the Tusculan lands to the Tusculans; and similar is the assignment of private property. Therefore, inasmuch as in each case some of those things which by nature had been common property became the property of individuals, each one should retain possession of that which has fallen to his lot; and if anyone appropriates to himself anything beyond that, he will be violating the laws of human society.

Render therefore to all men their dues. Tribute, to whom tribute is due: custom, to whom custom: fear, to whom fear: honour, to whom honour.
Owe no man any thing, but to love one another. For he that loveth his neighbour hath fulfilled the law.
For: Thou shalt not commit adultery: Thou shalt not kill: Thou shalt not steal: Thou shalt not bear false witness: Thou shalt not covet. And if there be any other commandment, it is comprised in this word: Thou shalt love thy neighbour as thyself.
The love of our neighbour worketh no evil. Love therefore is the fulfilling of the law.

For since every virtue is a habit that is the principle of a good act, a virtue must needs be defined by means of the good act bearing on the matter proper to that virtue. Now the proper matter of justice consists of those things that belong to our intercourse with other men, as shall be shown further on. Hence the act of justice in relation to its proper matter and object is indicated in the words, "Rendering to each one his right," since, as Isidore says (Etym. x), "a man is said to be just because he respects the rights [jus] of others."

Now in order that an act bearing upon any matter whatever be virtuous, it requires to be voluntary, stable, and firm, because the Philosopher says (Ethic. ii, 4) that in order for an act to be virtuous it needs first of all to be done "knowingly," secondly to be done "by choice," and "for a due end," thirdly to be done "immovably." Now the first of these is included in the second, since "what is done through ignorance is involuntary" (Ethic. iii, 1). Hence the definition of justice mentions first the "will," in order to show that the act of justice must be voluntary; and mention is made afterwards of its "constancy" and "perpetuity" in order to indicate the firmness of the act.

Accordingly, this is a complete definition of justice; save that the act is mentioned instead of the habit, which takes its species from that act, because habit implies relation to act. And if anyone would reduce it to the proper form of a definition, he might say that "justice is a habit whereby a man renders to each one his due by a constant and perpetual will"