 Studying Macbeth, here's how you can analyse Act 1, Scene 5 when we first meet Lady Macbeth. The scene begins with her reading a letter from Macbeth. This letter tells her of his encounter with the witches. Macbeth ends his letter by calling Lady Macbeth my dearest partner of greatness. This shows that he sees his wife as his equal. Lady Macbeth is really worried that Macbeth doesn't have it in him to kill King Duncan because she says he's too full of the milk of human kindness. This metaphor shows that she thinks that Macbeth is too loyal to King Duncan to carry out the witches' prophecies of becoming king. She plots to influence Macbeth to kill the king. Here she says, poor my spirits and thine ear. In other words, she wants to influence him to kill the king. Contextually, this led her to be called the fourth witch because she is using the supernatural spell upon Macbeth in order to force him to kill the king. She calls on the supernatural world to un-sex me here. This imperative sentence shows that she wants to become a man so that she can kill King Duncan herself but because she can't do this, she will use Macbeth.