Everybody's got a different circle of competence. The important thing is not how big the circle is. The important thing is staying inside the circle.

If you can't explain it to a six year old, you don't understand it yourself.

Try to become not a man of success, but try rather to become a man of value.

Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius -- and a lot of courage -- to move in the opposite direction.

Science without religion is lame. Religion without science is blind.

Everything should be made as simple as possible, but not simpler.