At the request of the League of Nations, Einstein and Freud collaborated in writing Why War? (1933). By the time the exchange between Einstein and Freud was published, Hitler, who was to drive both men into exile, was already in power, and the letters never achieved the wide circulation intended for them. The first German edition (Warum Krieg?) of the pamphlet is reported to have been limited to only 2,000 copies.

Einstein asks Freud: “What is to be done to rid mankind of the war menace?”