The imagery of blood is used to symbolize different things and meanings. Throughout the play Macbeth by William Shakespeare, the meaning of blood changes. As Macbeth and Lady Macbeth's attitudes and feelings alter after Duncan's murder, the meaning of blood alters as well. The symbolism of blood changes from courage to evil to guilt as Macbeth and Lady Macbeth not only become guiltier and more resentful, but also more comfortable as the murders progress.
Once the battle in Scotland has ended, blood is used to express courage and bravery. Macbeth is rewarded for being brave in battle and killing the traitor, Macdonwald. The captain exclaims, "For brave Macbeth (well he deserves that name), Disdaining Fortune, with his brandished steel, Which smoked the bloody execution," (1.2.18-20). The blood in the execution represents the courage that Macbeth displays. Macbeth committed a gruesome slaughter as he, "unseamed him from the nave to th' chops, And fixed his head upon our battlements," (1.2.24-25). The captain describes the bloody battle and how Macbeth never gave up. Macbeth is honored for his killing as Duncan orders his men to, "Go, pronounce his present death, And with his former title greet Macbeth," (1.2.74-76). King Duncan awards Macbeth with the title Thane of Cawdor for his courageous killing of Macdonwald. .
The symbolism of blood switches from courage to evil before Duncan is murdered. While waiting for the signal from Lady Macbeth, Macbeth hallucinates and sees a bloody dagger leading him to Duncan's room. "And, on thy blade and dudgeon, gouts of blood, Which were not so before. There's no such thing. It is the bloody business which informs," (2.1.58-60) implies that the blood represents the evil encouraging Macbeth to kill Duncan. His hallucination indicates that he may not want to kill the king but is being lead to do so. Since Lady Macbeth is convinced that Macbeth is not man enough to fulfill the prophecy and kill Duncan himself, she desires to become more like a man, so that she will be able to help with the action.