A knight-errant who goes mad for a good reason deserves no credit; the whole point consists in going crazy without cause

"I am sure," said Sancho, "that the knights who went through these penances were provoked and had some reason for doing so; but what cause have you, sir, for going mad? What lady turned you down? What signs have you discovered that her ladyship, Dulcinea of El Toboso, has committed any foolishness either with Moor or Christian?"

"That is just the point of it," said Don Quixote; "and that is where the subtleness of my plan comes in. A knight-errant who goes mad for a good reason deserves no thanks or gratitude; the whole point consists in going crazy without cause, and thereby warn my lady what to expect from me in the wet if this is what I do in the dry."

--Chapter XXV