Leonardo da Vinci carried a notebook with him at all times so that he could jot down ideas, impressions, and observations as they occurred. His notebooks (seven thousand pages exist; most scholars estimate that this is about one half of the amount he left to Francesco Melzi in his will) contained jokes and fables, the observations and thoughts of scholars he admired, personal financial records, letters, reflections on domestic problems, philosophical musings and prophecies, plans for inventions, and treatises on anatomy, botany, geology, flight, water, and painting.
