London wrote from a socialist viewpoint, which is evident in his novel "The Iron Heel". Neither a theorist nor an intellectual socialist, London's socialism grew out of his life experience. As London explained in his essay, "How I Became a Socialist", his views were influenced by his experience with people at the bottom of the social pit. His optimism and individualism faded, and he vowed never to do more hard physical work than necessary. He wrote that his individualism was hammered out of him, and he was politically reborn. He often closed his letters "Yours for the Revolution."