He who can, does; he who cannot, teaches.
Shaw's line comes from the Maxims for Revolutionists appended to Man and Superman (1903), and it became the most quoted insult to teaching in English. Woody Allen's Annie Hall later added a rung further down, for gym teachers. Aristotle had made the opposite case in the Metaphysics: the sign of someone who knows a thing is that he can teach it.
In practice
- A department passes over its best classroom teacher for head of subject in favour of a colleague with more publications.
- A parent tells a child who wants to teach that it is what people do when they cannot do the real thing.
- Standing
- An epigram rather than a tested claim. Doing and teaching are separate skills that the line treats as one, which is also why the best practitioner is not reliably the best teacher.
- Subject
- Learning & Education
- Essay
- Theories of teaching, and what schools are for