A novel's whole pattern is rarely apparent at the outset of writing, or even at the end; that is when the writer finds out what a novel is about, and the job becomes one of understanding and deepening or sharpening what is already written. That is finding the theme.
“Everything seems fine until you're about 40. Then something is definitely beginning to go wrong. And you look in the mirror with your old habit of thinking, 'While I accept that everyone grows old and dies, it's a funny thing, but I'm an exception to that rule.'”