At the Democratic convention, there was a parade of sad sacks, or victims — testifying to the harshness and injustice of America, particularly when governed by Republicans. There have been “ordinary Americans” at the Republican convention, too. But they have talked about striving and overcoming. One woman said, “The most liberating day of my life was the day I stopped saying, ‘Why me?’” If I can grossly, grossly simplify: The Democratic convention seemed to emphasize the half-emptiness of the American glass; and this one is emphasizing the half-full.