Economist, Socialist. One of the most influential social thinkers of history, and progenitor of the international Communist movement, his major work Das Kapital, explained why he thought capitalism would destroy itself, and his Communist Manifesto called on workers of the world to unite. What is perhaps most surprising about Marx is that he never explained how his projected classless society would actually operate. His followers including Lenin had no actual blueprint to follow. Critic Ludwig von Mises argued that Communism would prove to be inoperable without market prices, and the Soviet planners themselves eventually agreed that they could not work around this problem.