Dialectical materialism Dietzgen's most important contribution to Marxism was arguably his philosophical theory of dialectical materialism, a means of understanding the world which draws from Feuerbach's materialism and Hegel's dialectic. The same principles were developed independently by Karl Marx and Friedrich Engels and applied to their writings, of which the Communist Manifesto in particular had great influence on Dietzgen before he began writing. His works were quoted extensively by Lenin in the latter's philosophical polemic, Materialism and Empiriocriticism – notably the second to last work as against the very last, which is ignored entirely. Hence a list of Dietzgen's relevant philosophical works with accompanying dates of composition – not publication – can help to elucidate his philosophical evolution. He is also mentioned four times in Lenin's late Philosophical Notebooks (Collected Works, Vol. 38., Lawrence & Wishart, 1980) e.g. on pages 403 - 406 alongside Feuerbach. Georgi Plekhanov wrote on Dietzgen's philosophy, and this quotation with the quotation within it may be useful to provide the setting for the kind of arguments that his work provoked: "Now to Joseph Dietzgen. His son, Eugene Dietzgen, in a preface to the Russian translation, also describes his father’s philosophical teaching as an important supplement to Marxism (p iv). He says: If the founders of historical materialism, and their followers, in a whole series of convincing historical investigations, proved the connection between economic and spiritual development, and the dependence of the latter, in the final analysis, on economic relations, nevertheless they did not prove that this dependence of the spirit is rooted in its nature and in the nature of the universe. Marx and Engels thought that they had ousted the last spectres of idealism from the understanding of history. This was a mistake, for the metaphysical spectres found a niche for themselves in the unexplained essence of the human spirit and in the universal whole which is closely associated with the latter. Only a scientifically verified criticism of cognition could eject idealism from here. (p iv) Despite all our respect for the noble memory of the German worker-philosopher, and despite our personal sympathy for his son, we find ourselves compelled to protest resolutely against the main idea of the preface from which we have just quoted. In it, the relationship of Joseph Dietzgen to Marx and Engels is quite wrongly stated" Plekhanov may be arguing more with the son and the translator here rather