Harpo Marx York accent his entire life. According to those who personally knew him, Harpo's voice was much deeper than Groucho's, but it also sounded very similar to Chico's. His son, Bill, recalled that in private Harpo had a very deep and mature soft-spoken voice, but that he was "not verbose" like the other Marx brothers; Harpo preferred listening and learning from others. Harpo's final public appearance came on January 19, 1963 with singer/comedian Allan Sherman. Sherman burst into tears when Harpo announced his retirement from the entertainment business. Comedian Steve Allen, who was in the audience, remembered that Harpo spoke for
Karl Marx and the Close of His System has been seen as one of the most important discussions of Marx's economic theories, along with Rudolf Hilferding's "Böhm-Bawerk's Criticism of Marx", a defense of Marx against Bawerk. Bawerk's work is the "classical" critique of "Capital". Most subsequent critiques of Marxist economics have repeated Bawerk's arguments. Marxist economist Ernest Mandel identifies "Karl Marx and the Close of His System" as part of a literature, beginning with German social democrat Eduard Bernstein, that criticizes the dialectical method Marx borrowed from Georg Wilhelm Friedrich Hegel as "useless", "metaphysical", or "mystifying." He faults Böhm-Bawerk and the other critics for what he regards as