In Korsch's formulation, Hegel represented at the level of ideas the real, material progressiveness of the bourgeoisie. Alongside the extinction of 'Hegelianism' around 1848, the bourgeoisie lost its claim to that progressive role in society, ceasing to be the universal class. Marx, in taking Hegel and transforming that philosophy into something new, in which the workers would be the progressive class, himself represented the moment at which the revolutionary baton materially passed from bourgeoisie to workers. To Korsch, the central idea of Marxian theory was what he termed "the principle of historical specification". This means to "comprehend all things social in terms of a definite historical epoch". (Korsch, "Karl Marx", p. 24) He emphasizes that Marx "deals with all categories of his economic and socio-historical research in that specific form and in that specific connection in which they appear in modern bourgeois society. He does not treat them as eternal categories." (op. cit., p. 29f.) He was also noted for claiming that socialism must not confine itself to the "socialization of the means of production" and, instead, construct useful formula for the socialistic organization of the national economy.