All knowledge has an ultimate object. Knowledge for the sake of knowledge is, say what you will, nothing but a dismal begging of the question. We learn something either for an immediate practical end, or in order to complete the rest of our knowledge. Even the knowledge that appears to us to be most theoretical — that is to say, of least immediate application to the non-intellectual necessities of life — answers to a necessity which is no less real because it is intellectual, to a reason of economy in thinking, to a principle of unity and continuity of consciousness. But just as a scientific fact has its finality in the rest of knowledge, so the philosophy that we would make our own has also its extrinsic object — it refers to our whole destiny, to our attitude in face of life and the universe. And the most tragic problem of philosophy is to reconcile intellectual necessities with the necessities of the heart and the will. For it is on this rock that every philosophy that pretends to resolve the eternal and tragic contradiction, the basis of our existence, breaks to pieces.