Max Weber wrote his best-known work after he recovered from a period of serious mental illness near the turn of the twentieth century. After he recovered, his work transitioned from enthusiastically capitalist and liberal in the tradition of Adam Smith and John Stuart Mill to much more skeptical of the down-sides of modernization, more similar to the thinking of Nietzsche and Freud. In his first major work, The Protestant Ethic and the Spirit of Capitalism, Weber argues that the Protestant faith, especially Luther's notion of "calling" and the Calvinist belief in predestination set the stage for the emergence of the capitalist spirit. With his more complex understanding of the causes of capitalism, Weber accounts for the motivations of capitalists and the spirit of capitalism and rationalization in ways that Marx does not.