Marx Brothers made a guest appearance to introduce the "Tonight Show's" new host, Johnny Carson. Around 1960, the acclaimed director Billy Wilder considered writing and directing a new Marx Brothers film. Tentatively titled "A Day at the U.N.", it was to be a comedy of international intrigue set around the United Nations building in New York. Wilder had discussions with Groucho and Gummo, but the project was put on hold because of Harpo's ill-health and abandoned when Chico died in 1961. He was 74. Three years later, on September 28, 1964, Harpo died at the age of 75 of a heart attack
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