Shakespeare shows the theme instability and insanity while presenting Macbeth. He does this by using the metaphorical device ‘O, full of scorpions is my mind, dear wife! The connotations of scorpions are dangerous, poisonous and lethal, by saying his mind is full of these things he describes his own mind as poisoned and damaged which will lead him into making fatal actions. Macbeth’s brain is ‘full’ of poison which leads to the question of who diseased it in the first place? I think that Shakespeare’s authorial intention was to show that LM had been the one to disrupt Macbeth into doing what he had to do to become King.

~Act 3 scene 2