This was his advice to every mystic. Why was this? What concern is it of the mystic whether a pupil is grateful or not, sincere or not? Surely he has to do good to everyone. The idea is that unless a person is sincere, he is not ready to benefit and he will not do good. He must have sincerity and faith and sympathy. How true is that saying, "He who says evil of another knows him not; he who says good of another knows him better." This illustrates that sympathy is the only thing that discloses the secret of all things. For example, if you are fond of a certain composer's work, you will enjoy hearing one of his compositions far more than will a person who is prejudiced against that composer. Having closed his heart to that music, he will never enjoy it.