Book 7
1.128
Another tenet of theirs is the perpetual exercise of virtue, as held by Cleanthes and his followers. For virtue can never be lost, and the good man is always exercising his mind, which is perfect. Again, they say that justice, as well as law and right reason, exists by nature and not by convention: so Chrysippus in his work On the Morally Beautiful.
1.129
Neither do they think that the divergence of opinion between philosophers is any reason for abandoning the study of philosophy, since at that rate we should have to give up life altogether: so Posidonius in his Exhortations. Chrysippus allows that the ordinary Greek education is serviceable.
1.129
It is their doctrine that there can be no question of right as between man and the lower animals, because of their unlikeness. Thus Chrysippus in the first book of his treatise On Justice, and Posidonius in the first book of his De officio. Further, they say that the wise man will feel affection for the youths who by their countenance show a natural endowment for virtue. So Zeno in his Republic, Chrysippus in book i. of his work On Modes of Life, and Apollodorus in his Ethics.
