It is my fate to be considered an authority, since I spent my youth rebelling against it.

We scientists, whose tragic destination has been to help in making the methods of annihilation more gruesome and more effective, must consider it our solemn and transcendent duty to do all in our power in preventing these weapons from being used for the brutal purpose for which they were invented.

Jesus is too colossal for the pen of phrasemongers, however artful. No man can dispose of Christianity with a bon mot

The next world war will be fought with stones.

There is no vaccine against stupidity.

My pacifism is not based on any intellectual theory but on a deep antipathy to every form of cruelty and hatred.

I do not believe that a moral philosophy can ever be founded on a scientific basis. … The valuation of life and all its nobler expressions can only come out of the soul’s yearning toward its own destiny. Every attempt to reduce ethics to scientific formulas must fail. Of that I am perfectly convinced.