Epictetus starts by pointing out that for us to be harmed by another person's words or actions we have to believe that those things are harmful. It's not enough for someone to insult me, I have to believe that the sounds coming out of their mouth are harmful for it to hurt me. If someone is able to provoke me then I am at least partially to blame. Which is why we must not react to things before taking a moment to think.
That we are complicit when hurt by others is a truth that I know. I teach it to my kids. But I struggle to apply it consistently to my own life. Someone will do something or say something and I will be up in arms, ready to fight. Ready to blame the other person and make them pay.
Well, what if they are telling the truth? What if I deserved the treatment I got from them? And if they are not telling the truth, why do I invest so much in their opinions? Yes someone might try to physically harm me or threaten my security in some way, but they cannot keep me from the good. When we exclude indifferent things and even preferred indifferent things I must admit that no one can really harm me.
So I must take a moment before responding to orientate myself to what I know to be true. Then I will be able to keep control and live virtuously.