Monopoly-price is, as already observed, an artificial price in the sense that the laws of free market exchange do not apply to it. The "unique utilities," things not reproducible by human labor, command what might be termed natural monopoly-prices. There are many other commodities, however, the price of which is not regulated by the quantity of social human labor necessary to produce them, but simply by the desire of the purchasers and the means they have of gratifying it and the power of the sellers to control the market and exclude effective competition. Since Karl Marx wrote, the exceptions to his law of value have become more numerous, as a result of the changes in industrial and commercial conditions. The development of great monopolies and near-monopolies has greatly increased the number of commodities which, for considerable periods, are placed outside the sphere of the labor-value theory, their price depending upon their marginal utility, irrespective of the labor actually embodied in them or necessary to their reproduction. It may, in the opinion of the present writer, be said in criticism of the followers of Marx that they have not carried on his work, but largely contented themselves with repeating generalizations which, true when made, no longer fit all the facts. But that is not a criticism of Marx, or of his work. What he professed to make was an analysis of the methods of production and exchange in competitive capitalist society. His followers have largely failed to allow for the enormous changes which have taken place, and go on repeating, unchanged, his phrases.