He who CAN, does; he who cannot, teaches
There are many (frequently humorous) variations on this proverb.
1903
Maxims for Revolutionists
in
Man & Superman
230
He who can, does. He who cannot, teaches.
1979
Daily Telegraph
6 Aug. 8
A version of an old adage came to me—those who can, do, those who can't, attend conferences.
1981
Living Dog
i.
He who can, does sang the train wheels, he who cannot, teaches.
1995
Washington Post
29 Oct C1
George Bernard Shaw, who once observed that ‘he who can does; he who can't, teaches,’might be surprised to see what teachers are doing in politics these days.
efficiency and inefficiency
;
work