What was fun for me with this book [Lincoln in the Bardo] was to start out with the principle that went, "We're going to fight every day to make this not a novel; make it too short to be a novel." And then with that principle in place, the book sort of starts to say, "Okay, but I really need this. I really need some historical nuggets." And you're like, "All right, but keep it under control."