About this passageA short chapter on being wronged. Epictetus applies the school's account of judgement to the person who has done the harm: they acted on how things appeared to them, and a person cannot act on an appearance they do not have. The argument concludes that the one holding a false view is the one damaged by it. The chapter ends with a phrase offered as something to actually say under one's breath at the time.
When any person does ill by you, or speaks ill of you, remember that he acts or speaks from an impression that it is right for him to do so. Now it is not possible that he should follow what appears right to you, but only what appears so to himself. Therefore, if he judges from false appearances, he is the person hurt, since he, too, is the person deceived. For if anyone takes a true proposition to be false, the proposition is not hurt, but only the man is deceived. Setting out, then, from these principles, you will meekly bear with a person who reviles you, for you will say upon every occasion, "It seemed so to him."
In plainer words
When someone treats you badly or says something cruel, remember they are acting on how it looks from where they stand. They cannot act on how it looks to you — only on how it looks to them. So if they have got it wrong, they are the one operating on a false picture, and they are the one worse off for it. Get a fact wrong and the fact is unharmed; only the person is mistaken. Start from that and you can put up with someone insulting you, because you can say each time: that is how it seemed to him.
A restatement in modern English, written for this collection. The passage above is the text; this is one way of putting it.