It is often observed that American national identity is less a condition than an idea. What we have come to refer to as “the vision thing” is an expectation that our presidents will bring to the office a particularly strong sense of national mission. The four chronicled here (Thomas Jefferson, Calvin Coolidge, Herbert Hoover, Ronald Reagan) may have understood the special character of America in different ways, but in all cases a belief that there was a distinctly American way of doing things guided their decisions.