Socialism: Utopian and Scientific of thousands of copies. Throughout the decade of the 1860s, Karl Marx, close personal friend and political associate of Friedrich Engels, dedicated himself to the study of economics, culminating in the publication of the first volume of "Das Kapital" in 1867. Marx's lengthy and ponderous volume was extremely difficult for the average to penetrate, however, leading Engels to suggest to Marx in a letter of September 16, 1868 that a short popularized version of "Das Kapital" for a working class audience was urgently needed. "If it is not written, some Moses or other will come along and do it and
Karl Marx Library effort," Jordan presciently predicted. The first volume of the series, "On Revolution" (1971) broke little original ground for Marx scholars, containing only a spate of articles from the 1850s from Horace Greeley's "New York Tribune" on the contemporary situation in Spain that were not already readily available in other publications. Padover's failure to maintain a chronological presentation of documents was criticized by one reviewer, who observed that Marx's own views on the nature and time span of the revolutionary process evolved considerably during the second half of the 1800s. Padover's lengthy introduction to the first volume, "Karl Marx as Revolutionist,"