“He who can, does. He who cannot, teaches.”
George Bernard Shaw
Man and Superman (1903) “Maxims for Revolutionists”
Both of my parents were teachers and I was privileged enough to actually enjoy most of my schooling thanks to lucky placement within the UK comprehensive system and some dedicated and top class teachers. As such, I’ve always considered the above maxim to be somewhat unfair but at the same time could understand the underlying point especially when taken in the context of the more vocational subjects where the true subject matter experts tend towards actual work in their chosen sphere.