Philosophers, Karl Marx famously observed, sought to explain the world, but the real point was to change it. Marx himself explained and changed the world. He explained the development of human societies primarily in economic terms, asserting that history is driven by class struggle and predicting that capitalism would inevitably be replaced by communism. Marx didn't live to witness the establishment of a single Communist state. But during the 1920s, four decades after his death in 1833, revolutionaries inspired by his ideas seized power in Russia and created the Soviet Union. By mid-century, Communist governments ruled half the globe's population. It appeared that Marx's: predictions might prove correct. By the early 1990s, however, the Soviet Union had collapsed, and the majority of the world's Communist governments were cast aside. Moreover, communism as an economic model was abandoned virtually everywhere in favor of free-market, capitalist approaches. Despite this, Marx is far from irrelevant today. Much of what he wrote about capitalism-for example, that it would lead to the concentration of huge wealth in the hands of a few people-has been borne out. And Marx's insight that social relations are founded largely on material and economic conditions remains a key tool for explaining the world. Book jacket.