My father died a few days ago. He was 100 years old. I never met his parents, he barely knew them himself. His mother, the daughter of a Russian Jewish immigrant who fought for the Union, taught second grade in New York City public schools. She died when he was three, in the flu epidemic of 1918-1919, one of the greatest disasters in American history. A quarter of the American population, including President Wilson, caught the disease, and 700,000 died from it -- twice as many as fell in World War II. In New York City people were dying so...