Everyone confesses in the abstract that exertion which brings out all the powers of body and mind is the best thing for us all; but practically most people do all they can to get rid of it, and as a general rule nobody does much more than circumstances drive them to do.
Bio: Tobias Dantzig was a mathematician of Baltic German and Russian American heritage, the father of George Dantzig, and the author of Number: The Language of Science and Aspects of Science.