Experience is knowledge. All the rest is information.

Out of clutter, find simplicity.

We are all life trying to live, among other life trying to live.

Anger dwells only in the bosom of fools.

Science can only ascertain what is, but not what should be, and outside of its domain value judgements of all kinds remain necessary.

Most teachers waste their time by asking question which are intended to discover what a pupil does not know whereas the true art of questioning has for its purpose to discover what pupils knows or is capable of knowing.

The mere formulation of a problem is far more essential than its solution, which may be merely a matter of mathematical or experimental skills. To raise new questions, new possibilities, to regard old problems from a new angle requires creative imagination and marks real advances in science.