Legacy is what a president does that affects later generations.

Roosevelt understands that there are things that are worth surrendering your career for, like defending the country against [Adolf] Hitler.

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 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.

As parties began to develop around the turn of the 19th century, you had party nominees for President nominated in caucuses made up of party members in Congress.

So the result was that as one approached a political convention for most of the 19th century and for most of the 20th century until the 1960's, part of the drama was the fact that you didn't know ultimately who was going to be the nominee at the end of that convention week.

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.