Karl Marx (1818–1883), the German socialist philosopher, worked alongside Engels to shape the Communist Party, which Marx outlined in his seminal text The Communist Manifesto (1848). The German Ideology, also coauthored by Engels, explains Marx’s theory of history as defined by relationships based on material conditions. This work responds to contemporary philosophers—such as Hegel and Feuerbach—while leading the reader step by step through Marx’s materialist ideology.
From Karl Marx and Friederich Engels, The German Ideology. Moscow: Progress Publishers, 1968, Vol I. ch. 1, section A.