Before revision: Morgan would later have a significant influence on Karl Marx and on Friedrich Engels, who developed a theory of sociocultural evolution in which the internal contradictions in society generated a series of escalating stages that ended in a socialist society (see Marxism).
After revision: Morgan had a significant influence on Karl Marx and on Friedrich Engels, who developed a theory of sociocultural evolution in which the internal contradictions in society generated a series of escalating stages that ended in a socialist society (see Marxism).