One of my favorite books is Zen and the Art of Motorcycle Maintenance by Robert Pirsig. Less well known is Pirsig’s second book, Lila: An Inquiry Into Morals, which was published 17 years after Zen.
During those years, Pirsig took notes for Lila on small slips of paper. He used them like index cards, writing one idea on each slip and filing all the slips in a big box. (Many people — including Robert Greene and Ryan Holiday — still prefer this method.)
Pirsig ended up with over 11,000 slips. Most of these fell logically into various categories. But many did not.
To save his sanity, Pirsig created five special categories for rogue ideas. Consider using these categories whenever you organize any large body of notes: