In Act I, Scene 5, Lady Macbeth is presented as assertive, ambitious, and completely ruthless. After reading a letter from her husband in which he describes the witches' prophecy, she steels herself to prepare him to commit the wicked deeds that will make the prophecy a reality:
Come, you spirits
That tend on mortal thoughts, unsex me here
And fill me, from the crown to the toe, top-full
Of direst cruelty! Make thick my blood,
Stop up the access and passage to remorse...
Indeed, she pushes her husband to murder Duncan, and encourages him not to feel remorse after he has done so. By Act V, however, Macbeth has committed additional murders, and has gone beyond needing a push from his wife. She is no longer central to his life or essential to his plans, and more importantly, she is torn apartby guilt. Sleepwalking, she attempts to wash Duncan's imaginary blood from her hands in one of the most famous scenes in all of Shakespeare's plays:
Out, damned spot! Out, I say! One–two—
why then ’tis time to do't. Hell is murky. Fie, my lord, fie!
A soldier, and afeard? What need we fear who knows it,
when none can call our power to account? Yet who would
have thought the old man to have had so much blood in
She is consumed with guilt and has lost her grip on reality. Her suicide later in the act, it is clear, is the act of a shattered woman.