How does this work practically speaking? Lewis gets irritated when we say we are leaving for a restaurant at 7pm and Diane is not ready for another 10 minutes as he stands waiting at the door ready to go. When Lewis looks at his irritation he realizes that he is guilty of making Diane wait another 10 minutes in the kitchen after she has informed him that dinner is ready.
Next time your friend or partner does something that irks you, be as open-minded as possible, look at yourself to see whether you do the same thing that is irking you. That’s the mirror.