The only language men ever speak perfectly is the one they learn in babyhood, when no one can teach them anything!
We especially need imagination in science. It is not all mathematics, nor all logic, but it is somewhat beauty and poetry.
The greatest sign of success for a teacher... is to be able to say, 'The children are now working as if I did not exist.'
One test of the correctness of educational procedure is the happiness of the child.