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 their "positivist narrowness". The Marxist economist Paul Sweezy rejects Bawerk's view that the theory of value must be abandoned. However, he considers "Karl Marx and the Close of His System" to be the best statement of the argument that the fact that the law of value is not directly controlling in capitalist production requires the rejection of the theory of value. Karl Marx and the Close of His System Karl Marx and the Close of His System () is a critique of Karl Marx's economic theories by the Austrian economist Eugen Böhm von Bawerk, published in English translation in 1898.