Very few thinkers in history have formulated ideas, both in intellectual matters and in practical affairs, that have had an impact equal to those of Karl Marx (1818-1883). The intellectual, political, economic, and social influences of his ideas are sufficiently well known as to need no elaboration here. Like most intellectual geniuses, from the time of the ancient Greeks to the present, he formulated a complete, integrated intellectual system, which included elaborate conceptions of ontology and epistemology, of human nature, of the nature of society and the individual’s relationship to the social whole, and of the nature of the process of social history.