Every essay on this site began as a note, but most notes do not become essays. They stay where they were written: a line at the top of a page, a question with no answer under it, a word underlined twice for reasons I can no longer reconstruct.
For years I tore those pages out when a notebook filled up, keeping only the ones that had gone somewhere. That was a mistake. The notes that went nowhere were a record of what I noticed before I knew what it meant, which is a different and more honest record than the finished work.1
1 Finished essays are tidy about their origins. The notebook is the only place that remembers the false starts.
What to keep
Now I keep everything, and once a season I read the old notebooks back with a pencil in hand. A few notes turn out to be the beginning of something. Most do not. Either way, the reading is useful: it shows what I kept returning to without meaning to.
The rule I have settled on is simple. Date every page, never tear one out, and write the next note on the next line, not on a fresh page, so that the unfinished ones stay in company.