On her entry in the play in act 1 sc. 5 reading a letter from her husband, Lady Macbeth revealed her mind in two soliloquies. She wanted Macbeth become the king as prophesied by the witches, but doubted if her husband possessed the necessary evil in him to translate his ambition . As a devoted wife she chose to 'chastise' her husband with 'the valour of her tongue'. Lady Macbeth made a further apostrophe to the powers of darkness to fortify her with dire cruelty so that she could goad her husband to the heinous act of killing Duncan. On his return, Macbeth still looked very unsettled and it was she who again and again remonstrated him to prepare Macbeth for the 'deed'. Lady Macbeth herself drew the entire blue-print of the murder and prevailed upon her husband to work it out.
But after the murder and after the discovery of the murder, Lady Macbeth started betraying signs of mental degeneration and despair. She fainted amongst all after the discovery of Duncan's body in a pool of blood. We heard her regret that ' naught's had, all's spent '. She failed to rescue her husband from his strange paroxysm of fear when Banquo's ghost appeared at the coronation banquet. This change in the character of the Lady was most prominent in her sleep-walking in act 5 sc. 1. She was walking with a taper in her hand haunted by darkness and the terror of being condemned to hell. Almost all the moments of crime and guilt came back thick in her mind as we saw her rubbing her hands in a bid to clean them. She walked on muttering broken sentences, pathetically falling back on her and her husband's past doings. The Doctor diagnosed her disease as 'a slumbery agitation' beyond the possibility of cure. We saw how a strong and seemingly so cruel a woman turned into a sad victim of tragic nemesis.