Not the knowledge of a fact, but eternal Truth; through it we unite. So we come to the essence of religion, to the thought of uniting in Truth. The central thing is that Truth. In order to make one tolerant to another, we must not say, but waken, that he may understand. This reminds me of an amusing incident. Once I had a new pupil to whom I was giving instructions, and the last thing was, that before retiring every night he had to send thoughts of love and compassion to all living beings. This pupil was instantly horrified at the idea, and said: "yes, all, but not my neighboring country." I did not resist, took it tolerantly, understanding his sore heart. Would arguing have helped? No. So I said: "you are quite right. Forget the neighbor while thinking of humanity." The pupil smiled, he had expected an argument. Yet he felt not satisfied, and after six months he was able to think of the whole humanity. It is not preaching that is needed, but the hammering on the hearts, so that they naturally will understand.