Suppose one morning you’re walking to work and a man yells abuse and insults at you from across the street. As soon as you hear this abuse your mind changes from its usual state. You don’t feel so good, you feel angry and hurt. That man walks around abusing you night and day. Whenever you hear the abuse, you get angry, and even when you return home you’re still angry because you feel vindictive, you want to get even.
A few days later another man comes to your house and calls out, ”Hey! That man who abused you the other day, he’s mad, he’s crazy! Has been for years! He abuses everybody like that. Nobody takes any notice of anything he says.” As soon as you hear this you are suddenly relieved. That anger and hurt that you’ve pent up within you all these days melts away completely. Why? Because you know the truth of the matter now. Before, you didn’t know, you thought that man was normal, so you were angry at him. Understanding like that caused you to suffer. As soon as you find out the truth, everything changes: ”Oh, he’s mad! That explains everything!”
When you understand this you feel fine, because you know for yourself. Having known, then you can let go. If you don’t know the truth you cling right there. When you thought that man who abused you was normal you could have killed him. But when you find out the truth, that he’s mad, you feel much better. This is knowledge of the truth.