Never do anything against conscience even if the state demands it.
Nationalism is an infantile disease. It is the measles of mankind.
Most people say that is it is the intellect which makes a great scientist. They are wrong: it is character.
Most of the fundamental ideas of science are essentially simple, and may, as a rule, be expressed in a language comprehensible to everyone.
Morality is of the highest importance - but for us, not for God.
Memory is deceptive because it is colored by today's events.
Love is a better teacher than duty.
My religion consists of a humble admiration of the illimitable superior spirit who reveals himself in the slight details we are able to perceive with our frail and feeble mind.