Discourses: Book 4 6 : 2
But the first way is ineffectual and tedious—to attempt the very thing which Zeus himself has been unable to accomplish, that is, to convince all men of what things are good, and what evil. Why, that has not been vouchsafed to you, has it? Nay, this only has been vouchsafed—to convince yourself. And you have not convinced yourself yet! And despite that, bless me! are you now trying to convince all other men? Yet who has been living with you so long as you have been living with yourself? And who is so gifted with powers of persuasion to convince you, as you are to convince yourself? Who is more kindly disposed and nearer to you than you are to yourself? How comes it, then, that you have not persuaded yourself to learn? Are not things now upside down? Is this what you have been in earnest about? Not to learn how to get rid of pain, and turmoil, and humiliation, and so become free? Have you not heard that there is but a single way which leads to this end, and that is to give up the things which lie outside the sphere of the moral purpose, and to abandon them, and to admit that they are not your own? To what class of things, then, does another's opinion about you belong?—To that which lies outside the sphere of the moral purpose.—And so it is nothing to you?—Nothing.—So long, then, as you are stung and disturbed by the opinions of others, do you still fancy that you have been persuaded as to things good and evil?