By Ed Ayers, Brian Balogh and Peter OnufThis morning, on Independence Day, Americans will turn on their televisions or radios and hear Thomas Jefferson's ringing affirmation of human dignity:"We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness."But two centuries ago, when Americans gathered in churches or in the baking sun to recite the Declaration of Independence, they spoke mostly about killing their king. The opening parag...