A lot of it was, you know, you look for moments where, for instance, we were dependent on Abraham Lincoln making sure that the slaves were freed or John Kennedy bringing civil rights, or the first one I wrote about, George Washington trying to stop the British from invading and ending this country before it even began. Those were turning points where, if you had not had a president stepping up to the plate, if there wasn't a story like that, we would not be here.

Then you get to the last half of the 20th century, Americans are getting very skeptical about their leaders and their institutions, and another place that is affected is parties and conventions.

Legacy is what a president does that affects later generations.

First of all, there's no mention of political parties in the Constitution, so you begin American history with not only no political conventions but also no parties.

The point is that you see candidates running in these different kinds of contests. A primary shows you something that's different from a state party convention, which shows you something that is different than what a caucus shows you.

You have had presidential candidates over the last 30 years who would have had a very hard time getting nominated under the old system. One example is John Kennedy.

Lincoln was able to say, you know, "It will make me very unhappy if I lose the presidency, but I'm committed to larger things." If you look at candidates and say this is someone who can be happy to go back to their family or they have larger convictions. Franklin Roosevelt jeopardized his presidency by telling Americans in 1940, "We might have to fight Hitler." He loved being president, but he loved defending freedom more.