Lady Macbeth is one of Shakespeare’s most famous and frightening female characters. When we first see her, she is already plotting Duncan’s murder, and she appears to be stronger, more ruthless, and more ambitious than her husband. At one point, she wishes that she were not a woman so that she could do it herself. This theme of the relationship between gender and power is key to Lady Macbeth’s character. Some literary critics and historians argue that not only does Lady Macbeth represent an anti-mother figure in general, she also embodies a specific type of anti-mother: the witch.
Analysts see the conflict between femininity and masculinity in the character of Lady Macbeth, 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 single-minded pursuit of power. This conflict colours the entire drama, and sheds light on gender-based preconceptions from Shakespearean England to the present.
Lady Macbeth manipulates her husband with remarkable effectiveness, overriding all his objections. Aware her husband's temperament is "too full o' the milk of human kindness" for committing a regicide, she plots the details of the murder, then, countering her husband's arguments and reminding him that he first broached the matter, she belittles his courage and manhood, finally winning him to her designs. Lady Macbeth’s remarkable strength of will persists through the murder of the king—it is she who steadies her husband’s nerves immediately after the crime has been perpetrated.
Macbeth implies that she is a masculine soul inhabiting a female body, which seems to link masculinity to ambition and violence. Shakespeare, however, seems to use her, and the witches, to undercut Macbeth’s idea that “undaunted mettle should compose / Nothing but males” (1.7.73–74). These crafty women use female methods of achieving power—that is, manipulation—to further their supposedly male ambitions. Women, the play implies, can be as ambitious and cruel as men, yet social constraints deny them the means to pursue these ambitions on their own.
The fact that she conjures spirits likens her to a witch, and the act itself establishes a similarity in the way that both Lady Macbeth and the Weird Sisters use the metaphoric powers of language to call upon spiritual powers. This supernatural power in turn will influence physical events — in one case the workings of the state, in the other the workings of a woman's body. Like the witches, Lady Macbeth strives to make herself an instrument for bringing about the future. She proves herself a defiant, empowered nonconformist, and an explicit threat to a patriarchal system of governance in that, through challenging his masculinity, she manipulates Macbeth into murdering King Duncan. Despite the fact that she calls him a coward, Macbeth remains reluctant, until she asks: "What beast wasn't, then, that made you break this enterprise to me? / When you durst do it, then you were a man; / And to be more than what you were, you would / Be so much more the man." Thus Lady Macbeth enforces a masculine conception of power, yet only after pleading to be unsexed, or defeminised. The Weird Sisters are also depicted as defeminised, androgynous figures. They are bearded (1.3.46). Witches were perceived as an extreme type of anti-mother, even considered capable of cooking and eating their own children. Although Lady Macbeth may not express violence toward her child with that same degree of grotesqueness, she certainly expresses a sense of brutality when she states that she would smash the babe's head.
What makes Lady Macbeth more of a human character rather than a witch is the disintegration of her former ruthless self after the murder of Duncan. Just as ambition affects her more strongly than Macbeth before the crime, so does guilt plague her more strongly afterward. By the close of the play, she has been reduced to sleepwalking through the castle, desperately trying to wash away an invisible bloodstain. Once the sense of guilt comes home to roost, Lady Macbeth’s sensitivity becomes a weakness, and she is unable to cope. Significantly, she (apparently) kills herself, signaling her total inability to deal with the legacy of their crimes.