In 1968, Duchamp, precisely, reworked in a sketch "Femme aux bas blancs", a work by Courbet, and added a bird to it. Then, as nobody seemed to think of commenting this addition, he said: "this bird is bizarre indeed. And it is a hawk, too, which allows a play on words; this way, it is possible to see  the true and the false.
	..bas ...   "La chose en soie, les bas aussi...".