Lady Macbeth is a powerful presence in the play, most notably in the first two acts. Following the murder of King Duncan, however, her role in the plot diminishes. She becomes an uninvolved spectator to Macbeth's plotting, and a nervous hostess at a banquet dominated by her husband's hallucinations. Her fifth act sleepwalking scene is a turning point in the play, and her line, "Out, damned spot!," has become a phrase familiar to many speakers of the English language. The report of her death late in the fifth act provides the inspiration for Macbeth's "Tomorrow and tomorrow and tomorrow" speech.
Analysts see in the character of Lady Macbeth the conflict between femininity and masculinity, as they are impressed in cultural norms. Lady Macbeth suppresses her instincts toward compassion, motherhood, and fragility — associated with femininity — in favour of ambition, ruthlessness, and the singleminded pursuit of power. This conflict colours the entire drama, and sheds light on gender-based preconceptions from Shakespearean England to the present.