Musical high: Free, rockin’ and tight as a frog’s bottom

This is cobbled together from notes and from out-takes from my book, Beethoven's Anvil: Music in Mind and Culture, and my personal notes.

Zoom!!!
How are we to weigh and understand the following testimony, the first by Branford Marsalis, the second by Eric Clapton?

High, you feel high. It's easy to do it physically, but it's hard to do it mentally. I feel that musicians who say it happens every time they play are full of shit. The sublime cannot be routine. Three times, and you never forget them. It's with a combination of ...