What was new in what I did was: (1) to demonstrate that the existence of classes is tied only to definite historical phases of development of production; (2) that the class struggle necessarily leads to the dictatorship of the proletariat; (3) that this dictatorship is only a transition to the dissolution of all classes and leads to the formation of a classless society.

Letter to Joseph Weydemeyer [March 5, 1852]