A clever person solves a problem. A wise person avoids it.

Few are those who see with their own eyes and feel with their own hearts.

Most of the fundamental ideas of science are essentially simple, and may, as a rule, be expressed in a language comprehensible to everyone.

If one tries to navigate unknown waters one runs the risk of shipwreck.

I never teach my pupils; I only attempt to provide the conditions in which they can learn.

It is almost a miracle that modern teaching methods have not yet entirely strangled the holy curiosity of inquiry; for what this delicate little plant needs more than anything, besides stimulation, is freedom.

Only two things are infinite, the universe and human stupidity, and I'm not sure about the former.