Teachers
Aside from harmonica, one of my loves is Shakespeare. From Dame Judi Dench's book with Brendan O'Hea, Shakespeare: The Man Who Pays The Rent (St. Martin's Press 2023), O'Hea describes his drama teacher Rudi Shelley, who used to say, "I can't teach you how to act; all I can do is teach you how to learn how to act."
Remind you of any harmonica teachers you know?
I know of no teacher in any field who has spent more time than David studying how to teach and how we humans learn. And along the way, with his guidance, he really does teach players how to learn how to play.