Who was it that thus cried? Why, worthy thane,
You do unbend your noble strength, to think
So brainsickly of things.
– William Shakespeare
Macbeth, Act 2, Scene 2. Lady Macbeth says this to her husband when he talks of a voice telling him he will never sleep after killing Duncan. She dismisses the voice as his imagination. She tells him that he is just driving himself crazy thinking so obsessively about things.