There are, in fact, people who appear to think only with the brain, or with whatever may be the specific thinking organ; while others think with all the body and all the soul, with the blood, with the marrow of the bones, with the heart, with the lungs, with the belly, with the life. And the people who think only with the brain develop into definition-mongers; they become the professionals of thought. And you know what a professional is? You know what a product of the differentiation of labour is? Take a professional boxer. He has learnt to hit with such economy of effort that, while concentrating all his strength in the blow, he only brings into play just those muscles that are required for the immediate and definite object of his action--to knock out his opponent. A blow given by a non-professional will not have so much immediate, objective efficiency; but it will more greatly vitalize the striker, causing him to bring into play almost the whole of his body. The one is the blow of a boxer, the other that of a man. And it is notorious that the Hercules of the circus, the athletes of the ring, are not, as a rule, healthy. They knock out their opponents, they lift enormous weights, but they die of phthisis or dyspepsia. If a philosopher is not a man, he is anything but a philosopher; he is above all a pedant, and a pedant is a caricature of a man. The cultivation of any branch of science--of chemistry, of physics, of geometry, of philology--may be a work of differentiated specialization, and even so only within very narrow limits and restrictions; but philosophy, like poetry, is a work of integration and synthesis, or else it is merely pseudo-philosophical erudition. 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. But do all men face this contradiction squarely?