I was able to sit at Lincoln's side and see how he thought and how he acted, and how he felt about what was going on around him. I felt the pressures that were on him. You can see what people were writing to him, how they were nudging him.

If you think about it, the historian's task is like that of the detective.

Well, it seems to me Lincoln, I suppose, is kind of a model of a particular sort of presidency, a presidency that first of all is elected by a minority of the votes.

The big biography of Lincoln necessarily had to do so much with his political career, his ambitions, his accomplishments in public, with less time to spend on his private life, his inner life, and I thought this might be a way of getting at that.

At the beginning, Lincoln was so inexperienced he had reverence for military expertise, not realizing that there wasn't any military expertise, that the most anybody had commanded up to that point had been somebody, some troops in the Mexican War, and it had been years ago.

Here is Theodore Roosevelt with all his faults and with all his strengths - the devoted family man, the passionate game hunter, the astute politician, the frustrated warrior. This is a deeply moving account of the last years of a very great man.

Maybe I will write a memoir, perhaps I'll do some essays, or maybe I will write a mystery story.