is that knocking?—
How is’t with me, when every noise appals me?
What hands are here! Ha, they pluck out mine eyes.
Will all great Neptune’s ocean wash this blood
Clean from my hand? No, this my hand will rather
The multitudinous seas incarnadine,
Making the green one red.
Macbeth says this in Act 2, scene 2,
lines 55–61. He has
just murdered Duncan, and the crime was accompanied by supernatural portents.
Now he hears a mysterious knocking on his gate, which seems to promise
doom. (In fact, the person knocking is Macduff, who will indeed
eventually destroy Macbeth.) The enormity of Macbeth’s crime has
awakened in him a powerful sense of guilt that will hound him throughout
the play. Blood, specifically Duncan’s blood, serves as the symbol
of that guilt, and Macbeth’s sense that “all great Neptune’s ocean”
cannot cleanse him—that there is enough blood on his hands to turn
the entire sea red—will stay with him until his death. Lady Macbeth’s
response to this speech will be her prosaic remark, “A little water
clears us of this deed” (2.2.65). By the
end of the play, however, she will share Macbeth’s sense that Duncan’s
murder has irreparably stained them with blood.