「And who has lived so long with you as you with yourself? and who has so much power of convincing you as you have of convincing yourself; and who is better disposed and nearer to you than you are to yourself?」
「Remember that it is not he who reviles you or strikes you, who insults you, but it is your opinion about these things as being insulting. When then a man irritates you, you must know that it is your own opinion which has irritated you.」
― エピクテトス『語録』第4巻第6章