As I mentioned in my DC letter, I recently finished "Head and Heart" by Gary Willis. Willis has written often on American history and won a Pulitzer for his book on Lincoln's Gettysburg Address.  In this book he traces the history of the influence of religion on America as a back and forth movement between evangelical fervor and "enlightenment" thought, i.e., a view that seeks to be highly rational, emphasizing tolearance of various opinions.  So, for example, the revolutionary period followed a time of a religious revivalism known as the "Great Awakening."  Leaders had become cautious about one religious perspective insisting on its own way, and so the constitution (which does not mention God) is a secular document. However, a second "Great Awakening" came in the early 1800s , which had a major effet on the Westward expansion. And the process goes back and forth.  Sometimes these two persepctives converge, like in the Civil Rights movement and sometimes they are in conflict. Willis sees this process as a positive one which keeps America both open and spritually fresh.  Good book if you like a perspective on current politics!