Somewhat related: I was at Science North and they have a couple keyboards connected to a laser projector oscilloscope. I played Prelude in C (because I’m a beginner!) and it was kind of amazing to see not just the beauty of the loops and curves but how you could clearly see the progression of the chords on the wall.

I don’t feel like I’m getting any better at piano but I love, truly, how I keep “discovering” all the secrets, musically and mathematically.