What we observe is not nature itself, but nature exposed to our method of questioning."

"Every word or concept, clear as it may seem to be, has only a limited range of applicability."

Every tool carries with it the spirit by which it had been created.

An expert is someone who knows some of the worst mistakes that can be made in his subject and how to avoid them.

Even for the physicist the description in plain language will be a criterion of the degree of understanding that has been reached.