De Stoicorum repugnantiis

Moreover, Plato having said, that injustice, as being the corruption and sedition of the soul, loses not its power even in those who have it within them, but sets the wicked man against himself, and molests and disturbs him; Chrysippus, blaming this, affirms that it is absurdly said, A man injures himself; for that injustice is to another, and not to one’s self. But forgetting this, he again says, in his demonstrations concerning justice, that the unjust man is injured by himself and injures himself when he injures another, becoming to himself the cause of transgressing, and undeservedly hurting himself. In his books indeed against Plato, contending that we cannot speak of injustice against one’s self, but against another, he has these words: For men cannot be unjust by themselves; injustice requires several on opposite sides, speaking contrary one unto another. But no such thing extends to one alone, except inasmuch as he is affected towards his neighbor. But in his demonstrations he has such discourses as these, concerning the unjust man’s being injurious also to

himself: The law forbids the being any way the author of transgression, and to act unjustly will be transgression. He therefore who is to himself the author of acting unjustly transgresses against himself. Now he that transgresses against any one also injures him; therefore he who is injurious to any one whomsoever is injurious also to himself. Again: Sin is a hurt, and every one who sins sins against himself; every one therefore who sins hurts himself undeservedly, and if so, is also unjust to himself. And farther thus: He who is hurt by another hurts himself, and that undeservedly. Now that is to be unjust. Every one therefore that is injured, by whomsoever it is, is unjust also to himself.