How ignorant we are! How ignorant everyone is! We can cut across only a small area of the appallingly expanding fields of knowledge. No human being can know more than a tiny fraction of the whole. It must have been satisfactory in ancient times when one's own land seemed to be the universe; when research studies, pamphlets, books did not issue in endless flow; when laboratories and scientists were not so rapidly pushing back frontiers of knowledge that the process of unlearning the old left you gasping for breath.