She reads the letter her husband sent and realizes that she can be queen if Duncan is killed. She does not believe that Macbeth can kill Duncan because he is weak and too caring, so she wants to do it herself, as she said “... That tend to mortal thoughts, unsex me here and fill me from the crown...” (1,5, 40-41). Lady Macbeth wants to be treated like a man so she can do what her husband cannot do, will not do.
When Macbeth returns from battle, he was eager to hear what Lady Macbeth thought about the prophecies they were given from the three witches. Macbeth and Lady Macbeth have a difference of opinion when it came down to the prophecies “We will proceed no further in this business” (1,7,32-33) Macbeth said. Lady Macbeth pushed and pressured her husband into killing Duncan. She is the one who drove Macbeth mad. When the deed was done, all he could think about was if he was heard from someone close by. Macbeth was worried that he would get caught: “There’s one did laugh in’s sleep, and one cried ‘Murder!’,
That they did wake each other; I stood, and heard