“Now if we consider together the two points that have just been made — the point that no argument can add to the content of its premises, and the point that all arguments have to rest in the end on unproven premises — it becomes clear that the widely accepted notion that every truth needs to be proved, and that only what has been demonstrated is true, is the opposite of what is actually the case; in fact every proof must rest on foundations whose truth is not demonstrated, must go back eventually to something which is not the conclusion of an argument. We may be inclined, for as long as we do not think about it, to suppose that human knowledge about the world has come into existence through chains of reasoning, and is embodied in their conclusions, but in reality all the information we have is already embodied in the premises from which those very chains of reasoning begin — if we know anything about the world we know it not because it has been demonstrated or proved but because it has been directly experienced or perceived, or else because it follows by logical processes which contribute nothing all in the way of empirical content from what has been directly experienced or perceived. In this fundamental sense, all knowledge precedes all demonstration.”

–Bryan Magee, The Philosophy of Schopenhauer