31. Natural justice arises from a covenant between men for their mutual advantage to refrain from harming one another.

Alternate Translations: Bailey: The justice which arises from nature is a pledge of mutual advantage to restrain men from harming one another and save them from being harmed.

Cicero’s Defense of Epicurus: It remains to speak of Justice to complete the list of the virtues. But justice admits of practically the same explanation as the others. I have already shown that Wisdom, Temperance and Courage are so closely linked with happiness that they cannot possibly be severed from it. The same must be deemed to be the case with Justice. Not only does Justice never cause anyone harm, but on the contrary it always brings some benefit, partly because of its calming influence on the mind, and partly because of the hope that it provides of never-failing access to the things that one’s uncorrupted nature really needs. And just as Rashness, License and Cowardice are always tormenting the mind, always awakening trouble and discord, so Unrighteousness, when firmly rooted in the heart, causes restlessness by the mere fact of its presence. Once unrighteousness has found expression in some deed of wickedness, no matter how secret the act may appear, it can never be free of the fear that it will one day be detected. The usual consequences of crime are suspicion, gossip, and rumor – after that comes the accuser, then the judge. Many wrongdoers even turn evidence against themselves …..

And even if any transgressors think themselves to be well fortified against detection by their fellow men, they still dread the eye of heaven, and fancy that the pangs of anxiety that night and day gnaw at their hearts are sent by Providence to punish them. So in what way can wickedness be thought to be worthwhile, in view of its effect in increasing the distresses of life by bringing with it the burden of a guilty conscience, the penalties of the law, and the hatred of one’s fellow men?” Nevertheless, some men indulge without limit their avarice, ambition, love of power, lust, gluttony, and those other desires which ill-gotten gains can never diminish, but rather inflame. Such men are the proper subjects for restraint, rather than for reformation. Men of sound natures, therefore, are summoned by the voice of true reason to justice, equity, and honesty. For those without eloquence or resources, dishonesty is not a good policy, since it is difficult for such a man to succeed in his designs, or to make good his success once it is achieved. On the other hand, for those who are rich and intelligent, generous conduct seems more appropriate, for liberality wins them affection and good will, the surest means to a life of peace. This is especially true since we see that there is really no need for anyone to transgress, because the desires that spring from Nature are easily gratified without doing wrong to any man, and those desires that are vain and idle can be resisted by observing that they set their sights on nothing that is really desirable, and that there is more loss inherent in injustice than there is profit in the gains that it may bring for a time.

NewEpicurean Commentary: The concept of “justice” derives from the mutual advantage that comes from an agreement not to inflict or allow harm.