"Do not speak, but sing," said Zarathustra, and Schopenhauer ready fulfilled the command in great measure. Philosophy may be music--though it doesn't follow that music may be called philosophy. When a man has done his work, and gives himself up to looking and listening and pleasantly accepting everything, hiding nothing from himself, then he begins to "philosophise." What good are abstract formulae to him? Why should he ask himself, before he begins to think: "What can I think about, what are the limits of thought?" He will think, and those who like can do the summing up and the building of theories of knowledge. What is the earthly use of talking about beauty? Beautiful things must be created. Not one single aesthetic theory has so far been able to guess what direction the artists' mind will next take, or what are the limits to his creative activity. The same with the theory of knowledge. It may arrest the work of a man of learning, if he be himself afraid that he is going too far, but it is powerless to pre-determine human thought. Even Kant's counterposing of things-in-themselves to the world of phenomena cannot finally clip the wings of human curiosity. There will come a time when this unshakeable foundation of positivism will be shaken. All gnosiological disputes as to what thought can or cannot achieve will seem to our posterity just as amusing as the disputes of the schoolmen seem to us. "Why did they argue about the nature of truth, when they might have gone out and looked for truth itself?" the future historians will ask. Let us have an answer ready for them. Our contemporaries do not want to go out and seek, so they make a great deal of talk about a theory of knowledge.