Half a century ago, when Marx was writing Capital, free competition appeared to the overwhelming majority of economists to be a “natural law”. Official science tried, by a conspiracy of silence, to kill the works of Marx, who by a theoretical and historical analysis of capitalism had proved that free competition gives rise to the concentration of production, which, in turn, at a certain stage of development, leads to monopoly. Today, monopoly has become a fact. Economists are writing mountains of books in which they describe the diverse manifestations of monopoly, and continue to declare in chorus that “Marxism is refuted”. But facts are stubborn things, as the English proverb says, and they have to be reckoned with, whether we like it or not. The facts show that differences between capitalist countries, e.g., in the matter of protection or free trade, only give rise to insignificant variations in the form of monopolies or in the moment of their appearance; and that the rise of monopolies, as the result of the concentration of production, is a general and fundamental law of the present stage of development of capitalism.