The bourgeoisie is defined by Engels as the class of capitalists, who own the means of social production and are the employers of wage labour. In this sense the bourgeoisie does not include the intermediate middle class, whose labour is supervisory and intellectual. The proletariat or working class is in Marxism the political force that will destroy capitalism and effect the transition to socialism. Marxists associated with the Frankfurt school came to deplore the nonrevolutionary conservatism of western working classes and their gradual absorption into a growing middle class, and to put faith in other sources of revolution. The terms in their Marxist senses may appear somewhat dated, as society has changed so that the means of production are no longer generally owned by individuals, but by corporations, pension funds, and so forth, with a wider dispersion of shares. However, the extent to which this change disguises a concentration of real power in the hands of a few owners is also debated.