the fire and need not” (75-76). She means that she would never become involved in any dangerous situation if there is no need for her to do so. In an aside to Simple (so that Caius cannot hear), Mistress Quickly explains why she lied: she tells Simple that Doctor Caius himself is in love with Anne Page. But the housekeeper adds that Anne Page has no desire whatsoever to wed Caius (lines 91-92). Obviously, Mistress Quickly does want her master to blame her.
Doctor Caius, then, is quite angry; and he hands Simple a letter to bring to Hugh Evans. The letter is a challenge to a duel. Caius believes that Evans’ assistance in bringing Slender and Anne together will interfere with his own plans to marry Anne. As the angry doctor begins to leave his house, he threatens Mistress Quickly by telling her that if he does not win Anne Page as his wife, then he will dismiss Mistress Quickly from his service.