Integrity. Marcus Aurelius 4.8

This aphorism expresses one of Marcus' favorite lessons from philosophy, that conventional notions of harm and benefit poison our minds, causing us to suffer unnecessarily, and badly, because we feel deeply wounded or moved by things that should not touch us. You can find similar expressions in Seneca.

Ὃ χείρω αὐτὸν ἑαυτοῦ ἄνθρωπον οὐ ποιεῖ, τοῦτο οὐδὲ τὸν βίον αὐτοῦ χείρω ποιεῖ οὐδὲ βλάπτει οὔτε ἔξωθεν οὔτε ἔνδοθεν.

Whatever does not make a person worse than he is does not make his life any worse. Nor does it harm him in any way, on the outside or within.