"The bonsai is not you working on the tree; you have to have the tree work on you." ― John Naka
The first bonsai master I ever knew, John Yoshio Naka, would have been 100 years old today. Naka is considered the father of American bonsai. I never had the pleasure of working with him, but I have been taught (at seminars and demonstrations) by several of his students, including Harry Hirao, and I have taken lessons from students of his students. I've also read his books, Bonsai Techniques and Bonsai Techniques II, several times.
This is his masterpiece, a Foemina forest called "Goshin":
It can be seen at the U.S. National Aboretum, open on Fridays, Saturdays, Sundays and Mondays.