Lady Macbeth is just ambitious, but when she reads the letter from Macbeth about the prophecies she contemplates murder. She only cares about ‘the future in the instant’. This means that she doesn’t care how she achieves greatness, but uses her cleverness to convince Macbeth to kill King Duncan. Even as she loves him, she calls him ‘my dearest partner of greatness’, which shows that she is very aware of her position. She is calculating and knows exactly what her plans are to kill Duncan; she also tells her husband to look ‘innocent’ but to be a ‘serpent’.
She manipulates her husband by calling him a coward and using emotional blackmail to get her own way. She shows that she can remain in control and is the stronger one of the two, by not panicking and ordering Macbeth around. She tells him to ‘go carry (the daggers), and smear the sleepy grooms with blood’, and when he refuses she shows no remorse by taking the daggers herself. There are various influences on Lady Macbeth, but the letter from Macbeth telling her about the witches and the prophecies has the most effect.
The witches make her believe that it is possible for Macbeth to become king and Macbeth himself encourages her that she may be able to convince him to kill Duncan because when she asks him how long the king is staying at their castle, he replies ‘tomorrow, as he purposes’, which suggests to her that he has ambitions as well. She also talks about ‘spirits that tend on mortal thoughts’, so she thinks about dark subjects and can’t help herself, because they are ‘spirits’ and she has no power over them.
Lady Macbeth may be disturbed because of a child. She mentions ‘giving suck’, which could mean that she had a child, and she talks about it when she is trying to convince Macbeth to kill Duncan. This suggests that she has unpleasant memories of her child and they may have unhinged her because she talks about ‘how tender ‘tis to love the babe that milks me – I would… have dashed the brains out’. Shakespeare shows how Lady Macbeth is disturbed with scenes of her sleepwalking and talking to herself.
She hallucinates and begins to feel some remorse for what she has done because she thinks that her hands are stained with blood and ‘will ne’er be clean’, which shows that she has the death of Duncan on her conscience and can’t get away from it. She also feels guilty about the death of Lady Macduff, and she is a little scared of Macbeth because she says that ‘the Thane of Fife had a wife; where is she now’, so she could be worried that Macduff will come after her because of her husband’s misdeeds or that if Macbeth can kill a lady and all of her children, he might kill her as well in a moment of madness.