“During 1858 Marx finished his ‘A Contribution to the Critique of Political Economy’, upon which he had been engaged for nearly eight years in the intervals of his journalistic and political activities. The manuscript of this work, faithfully copied by Mrs. Marx, reached Duncker, the German publisher, in December, 1858, but the book did not appear until July or August of the following year. Marx chafed at the delay in publication and vowed that Herr Duncker should never publish another of his books. The same year, 1859, saw the publication of Darwin’s epoch-making work, ‘The Origin of Species’, and Marx regarded it as a fortunate coincidence that his own book appeared in the same year as that of Darwin. He recognised at once the importance and merit of Darwin’s work, and at once brought it to the attention of his fellow radicals at their meetings. Liebknecht has told us how for months the Marx circle spoke of nothing except the value of Darwin’s work. With great frankness Marx likened his own work in the sociological field to that of Darwin in the biological field, and he was always manifestly pleased when others made the comparison. Once, in the late sixties, when it had become a commonplace in Marxian circles, the now familiar comparison and Marx replied: “Nothing ever gives me greater pleasure than to have my name thus linked onto Darwin’s. His wonderful work makes my own absolutely impregnable. Darwin may not know it, but he belongs to the Social Revolution”” [John Spargo, Karl Marx: His Life and Work, 1910]