Plekhanov's importance in Russian history is beyond dispute. Almost singlehandedly, he launched the movement that was to culminate in the Bolshevik Revolution. He laid the theoretical foundations of Russian Marxism in Socialism and Political Struggle (1883) and Our Differences (1885); and, according to Lenin, his book On The Development Of The Monistic Concept Of History (1894) "reared a whole generation of Russian Marxists." He was the dominant figure in the first Russian Marxian organization, the Gruppa Osvobozhdente Truda (Emancipation of Labor Group), and almost all the leading personalities in the movement. including Lenin, began as his disciples. He was editor of the important publication Iskra and was responsible for the program of the Social Democratic Labor Party that was adopted in 1903. Ever the defender of orthodoxy, Plekhanov was in the forefront of the struggles against various heresies that successively arose from the mid-nineties on. For two decades the Social Democratic movement centered around him, and he remained a figure to be reckoned with until the end of his life.