All I really know in nonfiction is that when I come home, I've got all these notes and I'm trying to figure out what actually happened to me. I usually kind of know what happened, but as you work through the notes, you find that certain scenes write well and some don't even though they should. Those make a constellation of meaning that weirdly ends up telling you what you just went through. It's a slightly different process, but still there's mystery because when you're bearing down on the scenes, sometimes you find out they mean something different than what you thought.