Groucho Marx never discussed on-screen, but in a famous scene in "Duck Soup," where both Chicolini (Chico) and Pinky (Harpo) disguise themselves as Groucho, they are briefly seen applying the greasepaint, implicitly answering any question a viewer might have had about where he got his mustache and eyebrows. Marx was asked to apply the greasepaint mustache once more for "You Bet Your Life" when it came to television, but he refused, opting instead to grow a real one, which he wore for the rest of his life. By this time, his eyesight had weakened enough for him actually to need corrective lenses;
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"