“The theory must not contradict empirical facts,”

“If my theory of relativity is proven successful, Germany will claim me as a German and France will declare me a citizen of the world. Should my theory prove untrue, France will say that I am a German, and Germany will declare that I am a Jew.”

“Since the mathematicians have invaded the theory of relativity I do not understand it myself any more.”

“A theory is something nobody believes, except the person who made it. An experiment is something everybody believes, except the person who made it.”

“When I am judging a theory, I ask myself whether, if I were God, I would have arranged the world in such a way.”

“The supreme goal of all theory is to make the irreducible basic elements as simple and as few as possible without having to surrender the adequate representation of a simple datum of experience.”

“My pacifism is an instinctive feeling, a feeling that possesses me because the murder of men is disgusting. My attitude is not derived from any intellectual theory but is based on my deepest antipathy to every kind of cruelty and hatred.”