Lenard was a strong German nationalist, and did not like "English physics". He thought the English had stolen their ideas from Germany. He joined the National Socialist Party before it was popular. He said that Germany should rely on "Deutsche Physik" and ignore what he said were the false and deliberately misleading ideas of "Jewish physics". By this he meant the theories of Albert Einstein, including "the Jewish fraud" of relativity. He became an advisor to Adolf Hitler, and the Chief of Aryan physics.