Some things are in our control and others are not.

Things that are in our control are our decisions, desires, wishes – basically, our own thoughts and actions. Things that aren’t in our control are the thoughts and actions of others.

If you remember what is in your control and what is not in your control, then no one will trouble or threaten you. In addition, you will never find fault with anyone, or accuse anyone. You will do nothing that brings you pain. No one will hurt you. You will have no enemies. You will never be able to be harmed.

Try, then, to say to every difficult event, “You are but an appearance, and not really the thing you appear to be.” And then ask yourself, “Is this in my control, or isn’t it?” If it isn’t in your control, do not think about it any more.

– From The Enchiridion by Epictetus