Everyone in this world can be a teacher - but not a real teacher. A real teacher is the one who always teaches himself, and the more he teaches himself, the more he finds that there is so much to be taught. This self has so many lacks that a whole lifetime is not enough to teach it. The more the self learns, the more it overlooks the evil in others. It does not mean that the evil is in others; it only means that one finds in oneself the enemy which one was seeing outwardly. And the worst enemy one was faced with in outer life one finds to be in one's own heart. It makes one feel humiliated, but it teaches the true lesson: one finds oneself having the same element which one wishes to resist in another.