Marx wrote in the Communist Manifesto that ‘the history of all hitherto existing society is the history of class struggles’. But the statement needs qualification in its application to societies in which there were gradual gradations of rank rather than classes sharply defined by their different relationships to the modes of economic production. A critical issue for modern Marxism is whether there is a gradual intensification of class struggle in developing capitalist societies, or whether the embourgeoisement of the working classes undermines their revolutionary role. See also bourgeoisie/proletariat.