Karl Marx was a political radical whose work was devoted to analyzing capitalism and promoting its overthrow. His work fused philosophy, economics, history, and sociology. Marx proposed a view of history in which society was defined by its economic system, which changed over time in an evolutionary process. The engine of this change was class struggle—the antagonism between the wealthy and the poor in a given society, defined by their relationship to the economic "means of production." Marx viewed capitalism as a predatory and unjust system, and his work, chiefly in the Communist Manifesto and in his lengthy analysis of capitalism Capital (Das Kapital), was devoted to providing an analysis of capitalism that could be used to plot its overthrow. After capitalism, Marx believed, would come a just society in which the means of production would be owned by and used for the good of all, which he called communism.