A few notes: * 500 years ago there hadn’t been intensive centuries-long studies of many of these phenomena, so if you wanted to know something about it the onl

A few notes: * 500 years ago there hadn’t been intensive centuries-long studies of many of these phenomena, so if you wanted to know something about it the only way was to do independent investigation. * Even for subjects which had been studied, books were rare/expensive, poorly indexed, often contained a mishmash of disorganized material, hard to track down, and often flagrantly wrong but remaining uncorrected for centuries. * Leonardo was notoriously bad at sticking with any project, from his childhood on, easily abandoning his work and jumping to another topic, including leaving many of his paid projects unfinished. Probably serious ADHD. * There have been many intensely curious polymaths, but in many cases they didn’t take proper notes, the notes were lost/destroyed, the notes are buried in an archive somewhere where nobody reads about them, ...