Engels, like Marx, was a voluminous writer. Some of his better-known works are _The Peasant War in Germany_ (1850), _Germany: Revolution and Counter-Revolution_ (1851-52), _The Housing Question_ (1872), and _Anti-Dühring_ (1877-78). The latter work was written in reply to Eugen Dühring, a German professor who had published what, in Engels’ opinion, were erroneous ideas concerning materialism and socialism. Engels not only attacks Dühring’s views but goes on to sketch the communist world outlook, discussing dialectical and historical materialism, philosophy, and political economy. In _The Origin of the Family, Private Property, and the State_ (1884), Engels endeavors to show the relationship of the family, modes of production, and society. One of Engels’ latest writings on materialism is _Ludwig Feuerbach and the Outcome of Classical German Philosophy_ (1886). His _Dialectics of Nature_, published posthumously in 1927, is an attempt to discuss science from a Marxist viewpoint. JOINT AUTHORSHIP OF MARX AND ENGELS: As is well known, Marx and Engels often cooperated in writing, and sometimes it is difficult to determine exactly who wrote what. The best-known product of their collaboration, of course, is the _Communist Manifesto_. Engels, for example, wrote articles under Marx’s name for the latter to send to the New York _Tribune_. On the other hand, Engels, speaking of _Anti-Dühring_, said he read the whole manuscript to Marx and that Marx himself contributed a chapter. VLADIMIR I. LENIN: From roughly 1900 to his death, Lenin poured out pamphlet after pamphlet justifying violent revolution and giving instructions to his followers. In _What Is To Be Done?_ (1902), Lenin outlines the principles which should determine the formation of a Leninist-type Party. This was during the period of debate among Russian communists on the type of Party organization, with Lenin favoring a restricted, disciplined membership. In 1904, in _One Step Forward, Two Steps Back_, Lenin continues his demand for a disciplined Party. In this pamphlet he attacks his opponents, the Mensheviks. This attack was continued in _Two Tactics of Social-Democracy in the Democratic Revolution_ (1905). _Materialism and Empirio-Criticism_ (1909), a philosophical treatise, represents one of Lenin’s major works. In the years that followed, Lenin continued studying and writing. In 1917 _Imperialism: The Highest Stage of Capitalism_ appeared, in which Lenin develops the thesis that imperialism is the final state of monopoly capitalism. He characterized World War I as imperialistic on both sides. This work was destined to leave a lasting imprint on communist thinking. The term “imperialistic” is today one of the communists’ favorite terms of attack against the free world.