Not many of Karl Marx’s ideas were original. The concept of communism was known to the ancient world, while the notion of revolution is probably as old as politics itself. There are those who believe that Marx invented social class, but he himself was not of this party. Perhaps it was the idea of class struggle that he should have patented; but this, too, had long been familiar stuff to harassed mine owners and revolting peasants, if not always to political theorists. His vision of history as a succession of modes of production was a commonplace of the Enlightenment, and much of his thought was anticipated by Hegel.