The joint work of K. Marx and F. Engels "German Ideology," which remained incomplete and was not published during the lifetime of the founders of Marxism, represents an important stage in the formation of their views. It lays the foundations of a materialistic understanding of history, reveals the most important prerequisites for the communist transformation of society. It is permeated with passionate polemics with representatives of bourgeois and petty-bourgeois views, which played a large role in developing and upholding a new, truly scientific worldview.