here are neither room nor books in this house now, for the devil himself has carried all away.” “It was not the devil,” said the niece, “but a magician who came on a cloud one night after the day your worship left this
Though there are many tricks being played by Don Quixote' corrupted mind or those who play into his insanity for amusement, the real trickster element is being played out by those close to him that care for his shaken mental state and are trying to protect him. Here in the passage highlighted, his housekeeper, niece and barber Nicholas are tricking Don Quixote into thinking the source of his disease was taken by a wizard. With Sancho later in the story, he often plays into his fantasy either to agree with is master or to manipulate him out of laziness.