Mr. Marx has very decided opinions of his own, with some of which we are far from agreeing, but those who do not read his letters are neglecting one of the most instructive sources of information on the great questions of current European politics.
Editorial comments on Karl Marx's work as a foreign correspondent of the New York Tribune (7 April 1853), quoted by Robert C. Williams, Horace Greeley: Champion of American Freedom, New York: New York University Press, 2006, p. 135.