Most people can tire of a lecture in fifteen minutes, clever people can do it in five, and sensible people don't go to lectures at all.
Being a specialist is one thing, getting a job is another.
When actors begin to think, it's time for a change. They are not fitted for it.
It was Einstein who made the real trouble. He announced in 1905 that there was no such thing as absolute rest. After that there never was.