Religious liberty. It's humorous today that people who are religious and conservative are criticizing Jefferson because they saw him as supporting the separation of church and state. But what they don't understand is that their position on religion made it possible for various evangelical religions to flourish—the Baptists, the Methodists—by diminishing the power of the state church.
Why should President Obama read your book?
Political events are not shaped out of thin air, not only because of the constitutional legacy but the political legacy, the partisan legacy. I think that Obama assumed he could reach across the aisle. It may not be possible. I think if he read about Madison and Jefferson, he would realize that there are moments in history when you can't reach across the aisle.