I used to think everyone wanted to write books. The naïvété of youth, I suppose. To think that everyone thinks along the same lines as you.
For me, writing is the best way I know to organize my thoughts. I don’t even know what I really think about something until I begin to write. The very act of putting down (then re-arranging and altering) words on a page (or more often on a screen) is how I think best. The opaque becomes clear, or at least it sometimes does. That was how it was when I sought to write history — trying to weigh the evidence and give it a narrative thrust — and it’s how it is with fiction, though with novels it’s trying to see and hear characters in different scenes and bring them to life.