The term "Marxism" is much overused today: the category is deemed applicable by all sides of political divides unable to agree on anything else. No taxonomic sense, however, can be given to the conceptual chaos behind the wide variety of identifications. Only the historical reasons can be explored in the present context. Here Marxism will signify a tradition combining two related, originally 19th-century, intellectual complexes: (1) a particular, philosophically materialist, comprehensive world view seeking to give a unified, this-worldly explanation to all dimensions of human existence and (2) a "theory of movement" (R. Koselleck, 1989) oriented to the struggles of the industrial working class designed to accelerate historical time, to help bring a (logically, normatively or historically) necessary future closer to the present by "linking theory and practice". Both of these complexes are derived from the philosophy of history (or one of the philosophies of history) of Karl Marx, but the founder had little interest in working out a general Weltanschauung. In this respect Friedrich Engels was, in works such as Herr Eugen Dühring's Revolution in Science and the posthumous Dialectics of Nature, the founder of Marxism. Those who look back to the original work of Marx as against the tradition founded by Engels should be identified by the adjective "Marxian", as in Marxian philosophy, economics, social theory or anthropology, etc. Nevertheless Marx's relation to Marxism is too complex to allow a neat division between the two. As Lukács first demonstrated in 1923, Engels's interpretation of Marx's oeuvre in the sense of a generalized worldview and a unified science missed the actual philosophical depth of the latter's theory of history, social theory and critique of political economy.