Or have we eaten on the insane root
That takes the reason prisoner?
– William Shakespeare
Macbeth, Act 1, Scene 3. When the Witches appear amid claps of thunder to make their prophecies and then suddenly vanish, Banquo questions his sanity. He wonders if he and Macbeth have ingested the root of a poisonous plant that brought on madness. This could be a reference to hemlock or henbane, plants that can induce a state of madness. In this passage Shakespeare personifies the word “root” by giving it human characteristics. Foreshadowed here are Macbeth’s later hallucinations about a dagger, Banquo’s ghost and apparitions while visiting the Witches.