Macbeth Show how Macbeth and Lady Macbeth have to go against their own natures in order to kill Duncan. Each character in Macbeth has to either fight or give in to the evil. Because evil is contrary to human nature, Macbeth and Lady Macbeth have to go against their own conscience in order to murder Duncan. When the witches predict that Macbeth will become Thane of Cawdor and later, King of Scotland, he is stunned to silence by their prophecies. When murder enters Macbeths mind he is frightened by his thoughts. He tries to reject his impulse, declaring that he will leave everything to chance: ?If chance will have me