Karl Marx, born in Trier Germany in 1818, was a wide ranging thinker over fields that would now include sociology, economics, philosophy, and politics. His main theoretical achievement is what is sometimes called dialectical or historical materialism. This is essentially the position that the activity of Hegelian dialectic is not grounded in the pure realm of spirit and idea, as it was in Hegel, whose work strongly influenced Marx, but instead operates in the material realm of politics and economics as class struggle. The thesis and antithesis of Hegel become the two opposing classes, e.g. master and slave in classical society, peasant and aristocrat in feudalism, proletariat and bourgeoisie in capitalism, and the essential politico-economic tensions of these oppositions lead to the formation of a new system. He saw socialism or communism as the successor to capitalism.