If a man is crossing the river and an empty boat collides with his skiff, even though he is a bad tempered man he will not become very angry. But if he sees a man in the other boat he will scream and shout and curse at the man to steer clear. If you can empty your own boat crossing the river of the world, no one will oppose you, no one will seek to harm you. Thus is the perfect man - his boat is empty.