When Lucy accuses Lydia Quigley of being mad, Lydia responds with, "I know a hawk from a hand saw". This is a line from Hamlet by William Shakespeare. The full line (spoken by the title character) is, "I am but mad north-north-west. When the wind is southerly, I know a hawk from a handsaw". Hamlet is saying that, while his actions may appear mad, he still has his wits about him, and what appears as madness is really strategy and intellect. Mrs. Quigley may appear mad to those who know her machinations, but she is always cunning (no pun intended).