Joy is prayer; joy is strength: joy is love; joy is a net of love by which you can catch souls.

Too often the strong, silent man is silent only because he does not know what to say, and is reputed strong only because he has remained silent.  

Times and conditions change so rapidly that we must keep our aim constantly focused on the future.

Whoever undertakes to set himself up as a judge of Truth and Knowledge is shipwrecked by the laughter of the gods.

You ask me if I keep a notebook to record my great ideas. I've only ever had one.

In wartime, truth is so precious that she should always be attended by a bodyguard of lies. 

Most people spend more time and energy going around problems than in trying to solve them. 

Religion is a matter of faith. Science has to face challenges at every step.

I want to put a ding in the universe.

Thou wilt find rest from vain fancies if thou doest every act in life as though it were thy last.

Whenever I hear anyone arguing for slavery, I feel a strong impulse to see it tried on him personally.