How does Shakespeare present the theme of guilt in Macbeth act 2 scene 2?

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...

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.