I've just finished reading Shakespeare's all-time greatest hit Hamlet in my English class and it has now become clear to me that a great many phrases from this work have entered our language, especially on this board. I've seen such expressions as "there's the rub", "mortal coil" and "a hit, a very palpable hit" multiple times on this board. It's nice now knowing whence these sayings are.

Aside from this just being a point I wanted to make, what other immortal expressions have we cut from the folios of great tomes of literature and pasted into our own lexicons?