and principal architect of the success of the Bolshevik revolution in Russia in 1917. Philosophically Lenin contributed a number of ideas to Marxism: these include emphasis on the role of a professional revolutionary vanguard, drawn from the intelligentsia, the moral absolutism whereby everything may be sacrificed to the revolution, and the association of imperialism with capitalism that partly explained why Russia, which was not a developed capitalist economy, might nevertheless be in the vanguard of the revolution. Influential works by Lenin include The Development of Capitalism in Russia (1899), What is to be Done? (1902), and Imperialism, the Highest Stage of Capitalism (1916). His earlier Materialism and Empirio-Criticism (1909) is an attack on what he saw as the subjective idealism of Russian thinkers influenced by Avenarius and Mach.