Marx Brothers "The Cocoanuts" (1925–1926) and "Animal Crackers" (1928–1929). Playwright George S. Kaufman worked on the last two and helped sharpen the brothers' characterizations. Out of their distinctive costumes, the brothers looked alike, even down to their receding hairlines. Zeppo could pass for a younger Groucho, and played the role of his son in "Horse Feathers". A scene in "Duck Soup" finds Groucho, Harpo, and Chico all appearing in the famous greasepaint eyebrows, mustache, and round glasses while wearing nightcaps. The three are indistinguishable, enabling them to carry off the "mirror scene" perfectly. The stage names of the brothers (except Zeppo) were
Karl Marx and the Close of His System labour value, he argues that the basic error in Marx's system resulted from a self-contradiction of Marx's law of value, namely how the rate of profit and the prices of production of the third volume of Marx's "Capital" contradict Marx's theory of value in the first volume. He maintains that since the law of value is not directly controlling in capitalist production, the theory of value must be abandoned. Bawerk also attacks Marx for downplaying the influence of supply and demand in determining permanent price, and for deliberate ambiguity with such concepts. "Karl Marx and the Close of His System"