(Epicurus thinks that those are natural and necessary which put an end to pains, as drink when one is thirsty; and that those are natural but not necessary which only diversify pleasure, but do not remove pain, such as expensive food; and that these are neither natural nor necessary, which are such as crowns, or the erection of statues.)
31. “Those desires which do not lead to pain, if they are not satisfied, are not necessary. It is easy to impose silence on them when they appear difficult to gratify, or likely to produce injury.
32. “When the natural desires, the failing to satisfy which is, nevertheless, not painful, are violent and obstinate, it is a proof that there is an admixture of vain opinion in them; for then energy does not arise from their own nature, but from the vain opinions of men.
33. “Natural justice is a covenant of what is suitable, leading men to avoid injuring one another, and being injured.
34. “Those animals which are unable to enter into an argument of this nature, or to guard against doing or sustaining mutual injury, have no such thing as justice or injustice. And the case is the same with those nations, the members of which are either unwilling or unable to enter into a covenant to respect their mutual interests.
35. “Justice has no independent existence; it results from mutual contracts, and establishes itself wherever there is a mutual engagement to guard against doing or sustaining mutual injury.
36. “Injustice is not intrinsically bad; it has this character only because there is joined with it a fear of not escaping those who are appointed to punish actions marked with that character.
37. “It is not possible for a man who secretly does anything in contravention of the agreement which men have made with one another, to guard against doing, or sustaining mutual injury, to believe that he shall always escape notice, even if he have escaped notice already ten thousand times; for, till his death, it is uncertain whether he will not be detected.
38. “In a general point of view, justice is the same thing to every one; for there is something advantageous in mutual society. Nevertheless, the difference of place, and divers other circumstances, make justice vary.