Keeping a writer's notebook in public imposes an unbeatable rigor, since you can't slack off and leave notes so brief and cryptic that they neither lodge in your subconscious nor form a record clear enough to refer to in future. By contrast, keeping public notes produces both a subconscious, supersaturated solution of fragmentary ideas that rattle around, periodically cohering into nucleii that crystallize into full-blown ideas for stories, novels, essays, speeches and nonfiction books.