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 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.