The renowned critic Harold Bloom writes of Macbeth:
Macbeth is most "a tragedy of blood," not just in its murders but in the ultimate implications of Macbeth's imagination itself being bloody. The usurper Macbeth moves in a consistent phantasmagoria of blood: blood is the prime constituent of his imagination. He sees that what opposes him is blood in one aspect--call it nature in the sense that he opposes nature--and this opposing force thrusts him into shedding more blood. "It will have blood, they say: blood will have blood."
Macbeth speaks these words after confronting Banquo's ghost. And, it is at this point that Macbeth continues his bloody path of "vaulting ambition" following his illusions and dreams against nature. In Act I, for instance, the sergeant describes how brutally Macbeth slay the treacherous Thane of Cawdor,
For brave Macbeth—well he deserves that name—
Disdaining fortune, with his brandish'd steel,
Which smoked with bloody execution,(20)
Like valor's minion...
(The entire section contains 2 answers and 868 words.)