But in the great work of Marx the socialist theory is elaborated with a fulness of learning and a logical power to which Rodbertus has no claim. With Marx the doctrine of surplus value receives its widest application and development: it supplies the key to his explanation of the history and influence of capital, and consequently of the present economic era, which is dominated by it. It is the basis, in fact, of a vast and elaborate system of social philosophy. In any case it is an absurdity as well as an historical error to speak of Marx as having borrowed from Rodbertus. Marx was an independent thinker of great originality and force of character, who had made the economic development of modern Europe the study of a laborious lifetime, and who was in the habit, not of borrowing, but of strongly asserting the results of his own research and of impressing them upon other men. The great work of Marx may be described as an exposition and criticism of capital. But it is also indirectly an exposition of socialism, inasmuch as the historical evolution of capital is governed by natural laws, the inevitable tendency of which is towards socialism. It is the great aim of Marx to reveal the law of the economic movement of modern times. Now, the economic movement of modern times is dominated by capital. Explain, therefore, the natural history of capital, the rise, consolidation, and decline of its supremacy as an evolutionary process, and you forecast the nature of that into which it is being transformed—socialism. Hence the great task of the Marx school is not to preach a new economic and social gospel, not to provide ready-made schemes of social regeneration after the fashion of the early socialists, nor to counteract by alleviating measures the wretchedness of our present system, but to explain and promote the inevitable process of social evolution, so that the domination of capital may run its course and give place to the higher system that is to come.