What of the argument that the play 'Macbeth' is entirely psychological? The first lines Macbeth says in the play: 'So foul and fair a day I have not seen' and this seems to echo the word-choice of the Weird Sisters: 'When the battle's lost and won'. Is there an unconscious link from the start?
Hmmm. You know, I've never really thought about it. Might have to go back and check it out.