Lady Macbeth has such power over Macbeth. She is a manipulative woman, who will stop at nothing to see that her husband gets what is foretold to him. She hears the witches and decides to help their visions come true. Lady Macbeth conceives the idea of killing Duncan
No, the witches in Macbeth were there to plant seeds in Macbeth's head that would soon sprout into disaster,but Lady Macbeth was not directly influenced,she even had her own part into descencding macbeth into insanity,.The only thing the witches did to Lady Macbeth was grow her greed and tighten her control on Macbeth.
