Eisenhower embraced the work of San Francisco philosopher Eric Hoffer, who explained in his 1951 book The True Believer: Thoughts on the Nature of Mass Movements that economically or culturally dispossessed people were natural targets for political and religious extremists. They could easily be manipulated to back a demagogue who promised to resurrect a world in which they had enjoyed prosperity and cultural significance. Such a leader was dangerous enough during the Nazi era, Eisenhower thought, but with the advent of nuclear weapons in 1945, such a strongman could destroy humanity.