On the eve of World War II, Einstein endorsed a letter to President Franklin D. Roosevelt alerting him to the potential development of "extremely powerful bombs of a new type" and recommending that the U.S. begin similar research. This eventually led to what would become the Manhattan Project. Einstein supported defending the Allied forces, but largely denounced the idea of using the newly discovered nuclear fission as a weapon. Later, with the British philosopher Bertrand Russell, Einstein signed the Russell–Einstein Manifesto, which highlighted the danger of nuclear weapons.
Imagination is more important than knowledge.
Anyone who has never made a mistake has never tried anything new.
The important thing is not to stop questioning. Curiosity has its own reason for existing.