It is interesting to note how the theme of guilt is portrayed through both Macbeth and Lady Macbeth in act 2, scene 2.

The scene begins with Lady Macbeth announcing her lack of guilt. She claims that drink has made her "bold" and that she feels nothing but triumph in the death of King Duncan. Of course, there is a note of ambivalence on the matter when Lady Macbeth claims she could not do the stabbing herself since Duncan resembles her father in his sleep, yet she seems confident and happy.

Macbeth, on the other hand, is tormented by what he has done. Though Lady Macbeth tells him not to think too much about the killing, Macbeth claims he has "murdered sleep"—that is, he knows he will never be able to relax again, not only from feeling horrible about killing a good king but from the fear that he will eventually be found out. He is so affected that he does not want to plant the weapons on the guards because he does not want to have to look at Duncan's corpse.

Sleep acts as a motif for peace in other ways as well. When the Macbeths hear knocking at the end of the scene, Macbeth laments that he wishes the noise would "[w]ake Duncan with thy knocking!" This spells out his guilt most clearly.

Water imagery also relates to the theme of guilt. Water is usually a sign of spiritual cleanliness or even rebirth. However, here water loses all its restorative properties for Macbeth. Macbeth sees his hands covered in blood and claims that "all great Neptune's ocean" might not ever make his hands clean again. He feels nothing can be done to atone for his crime, especially since he plans on reaping the benefits of having Duncan out of the way. In contrast, Lady Macbeth claims "a little water clears us of this deed" and that once the shock of the crime is gone, it will be smoothing sailing from there.

In Act II, Scene ii, Shakespeare presents the theme of guilt primarily through the character of Macbeth. First of all, Shakespeare introduces the motif of blood to demonstrate Macbeth's feelings of regret after committing the murder. Looking down at his blood-stained hands, for example, Macbeth proclaims that his hands make for a "sorry sight."

In addition, Shakespeare also presents the theme of guilt in a religious context. Macbeth, for instance, is unable to say the word "Amen," which he interprets as a sign that God could not give him a blessing because of the terrible crime that he has just committed.

In this scene, we also find numerous references to Macbeth being the murderer of "sleep." These repeated references to a lack of sleep highlight Macbeth's guilty conscience. Sleep is associated with innocence, peace, and a clear conscience, and being unable to sleep is a physical manifestation of Macbeth's guilt.

In Act II, Scene 2, the magnitude of Macbeth's crime of regicide has awakened in him a tremendous feeling of guilt that manifests itself as blood.

That Macbeth has had misgivings about murdering Duncan is indicated by Macbeth's imagining that a dagger hangs in the air before him. On the blade of this dagger there are "dudgeon gouts of blood" (2.1.47).
Then, in Scene 2 after he sees his wife following his wicked deed of killing King Duncan, Macbeth looks at his bloody hands and says, "This is a sorry sight"(2.2.20). Lady Macbeth tells her husband not to dwell on his foolish thought. Nevertheless, blood serves as a symbol for Macbeth's guilt because he feels that "all great Neptune's ocean" (2.2.61) cannot wash away this blood from his hands. 

Lady Macbeth scolds her husband, saying that a little water will wash the blood from his hands, and that it is merely his firmness of purpose that has left him. Further, Lady Macbeth urges her husband to not dwell on his thoughts of guilt and just dismiss them. Ironically, however, she later imagines that she herself sees blood and cannot wash it away.