Having drugged the guards of Duncan's chamber, Lady Macbeth now meets her husband in the lower courtyard as he emerges from the king's room itself. Macbeth's conscience is clearly disturbed by what he has done, and once more his wife criticizes his lack of firmness. The success of their plot is also in jeopardy because Macbeth has brought the daggers with him. Lady Macbeth returns to the scene of the murder in order to place the daggers and to smear the king's sleeping servants with blood, a deed that presents her with none of the horror that now affects Macbeth. As the scene closes, we hear, with the Macbeths, a loud and persistent knocking at the door.
Lady Macbeth's opening words introduce a new level of emotional intensity. Fear of failure has been replaced with fear of discovery, and even though she describes herself as drunk with boldness and on fire with passion, she is just as easily alarmed as her husband is by the tiniest noises and movements. Her swift changes of thought and speech foreshadow the language of her final lapse into madness in the sleepwalking scene (Act V, Scene 1), when she relives these same moments.
Yet, despite all this, Lady Macbeth appears to be sufficiently hardened to the deed to be able to make several horribly ironic comments, including the observation that she would have committed the murder herself, had she not been put off the idea by the resemblance of the sleeping king to her own father. Note the similarity of this line — by which she seems to excuse something lacking in herself — with her earlier taunt to Macbeth that she would have dashed out the brains of her own child had she sworn to do so. The fact is that what Lady Macbeth would do her husband has actually done. The total reversal of roles that she anticipated cannot now occur because, despite his stricken conscience, Macbeth has done what she could never do.
The quick-fire dialogue and fragmented line structure in this part of the scene denote a sense of frightened urgency in both characters. Macbeth's concern centers on two major areas. First, he believes he has "murder'd sleep." Sleep, he argues, ought to bring physical calm in the same way that prayer soothes the spirit. But in his case, the ability both to pray and to sleep has been cancelled. Macbeth is haunted by the knowledge that he will never again rest easy in his own bed: "Glamis hath murdered sleep, and therefore Cawdor / Shall sleep no more, Macbeth shall sleep no more!" (41-42). Lady Macbeth, refusing to accept such "brainsickly" thoughts, reminds Macbeth of the familiar comparison that "the sleeping and the dead / Are but as pictures." Ironically, she is the one who will be kept from sleeping by the picture of death long after it has left Macbeth's mind.
The second area of Macbeth's concern is the bloodiness of the deed and specifically the fact that his own hands bear witness to the unnatural deed of murder. Again, for Lady Macbeth, blood is only like paint used to daub the picture of death and can be easily washed off. But Macbeth is aware of the deep stain beneath the surface. His capacity for recognizing the grand scale of his action, which foreshadows his later remark that he is "in blood stepped in so far," is missing in Lady Macbeth.
At this point, the knocking begins. Like the beating of the heart in Edgar Allan Poe's short story "The Tell-Tale Heart," the noise is partly the knocking of their consciences and partly an actual exterior knocking. Symbolically, the knocking is the knocking of justice, or of vengeance.
bellman (3) man who summoned condemned prisoners
surfeited (5) drunk
their charge (6) that is, Duncan
second course (38) that is, at the banquet of life
gild (55) paint them with golden blood
incarnadine (61) make red