The Founding Fathers would be sorry to see that America had become so divided and factionalized.

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.

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 original thing that fascinated me most was why we expect leaders, and especially presidents, at times to destroy themselves - and that's a sign of being a good leader or a good president. We usually don't expect that of almost anyone else in any profession, in particular, in public life.

The founders were very worried that if parties developed in America, you might have something like the modern Italian system, where you have 20 different parties that divide Congress and the country and can't govern.

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.

I'm defining [presidential courage] pretty narrowly. It's not only taking a big political risk but it's also the risk that in the hindsight of history, people think it's wise.