Before he kills Duncan, Macbeth is plagued by worry and almost aborts the crime. It takes Lady Macbeth’s steely sense of purpose to push him into the deed. After the murder, however, her powerful personality begins to disintegrate, leaving Macbeth increasingly alone. He fluctuates between fits of fevered action, in which he plots a series of murders to secure his throne, and moments of terrible guilt (as when Banquo’s ghost appears) and absolute pessimism (after his wife’s death, when he seems to succumb to despair)