"There's an expectation that, if you turn over a page of any moment in history, you'll find creepy-crawly things that will disillusion you," he says. "Certainly, there are people who are revered who turn out to be monsters. But some survive the passage of time with their glow intact — and that's true of Lincoln. He was a genuinely great man. It's sort of embarrassing to say that in a day and age where people reflexively hate politicians."