“Our immediate interests are after all of but small moment. It is what we do for the future, what we add to the sum of man's knowledge, that counts most. As someone has said, 'The individual withers and the world is more and more.' Man dies at 70, 80, or 90, or at some earlier age, but through his power of physical reproduction, and with the means that he has to transmit the results of effort to those who come after him, he may be said to be immortal.”