Striving for social justice is the most valuable thing to do in life.

Heroism on command, senseless violence, and all the loathsome nonsense that goes by the name of patriotism - how passionately I hate them!

Playfullness is the essential feature of productive thought.

I am not only a pacifist but a militant pacifist. I am willing to fight for peace. Nothing will end war unless the people themselves refuse to go to war.

Insofar as mathematics is true, it does not describe the real world. Insofar as it describes the real world, it is not true.

How many people are trapped in their everyday habits: part numb, part frightened, part indifferent? To have a better life we must keep choosing how we are living.

I refuse to engage in an intellectual battle with an unarmed man.