The Witches
I think that the biggest symbol in Macbeth are the three witches. I think this because they symbolize human desire, but also hidden truth. They resemble desire, because Macbeth wants to be king, and I'm sure that Banquo would like his children to be future kings. Just by saying to Macbeth that he will be king, they lead him, undirectly, to make him go on his killing sprees. If they did not tell Macbeth he was to be king, he would still be a loyal general to Duncan.
They also have hidden truth in their talk because they say that Banquo will never be king; and surely Banquo is eventually murdered. They also say that Macbeth will not be overthrown until Birnam Wood walks to his castle and that no man born of a woman will kill him. This leads Macbeth to think he is invincible. Eventually Birnam Wood does "walk" to his castle. Macduff's mother had a C-section, which makes it true that Macduff was not born of a woman. This shows that the witches hide the downside of the future in the words. It also shows that the witches are the biggest symbol in Macbeth.
