"Falling in love is not at all the most stupid thing that people do-but gravitation cannot be held responsible for it."

"Peace cannot be kept by force; it can only be achieved by understanding."

"It is not enough to teach a man a specialty. Through it he may become a kind of useful machine but not a harmoniously developed personality."

"If I were not a physicist, I would probably be a musician. I often think in music. I live my daydreams in music."

"I am not only a pacifist but a militant pacifist. I am willing to fight for peace."