Blood is essential to every human beings survival. It is a fluid circulating throughout the body that carries nutrients and oxygen to the tissues in exchange for life and if this was somehow lost then the life would also be lost. No matter what caused the loss of blood, if it were jealousy, revenge, guilt or treachery the life would still be forfeit. In Macbeth there are many symbolic gestures towards blood, which ultimately develop into the main dominating theme of the play. In the beginning of the play blood is symbolized for MacBeth's honor and courage, half way through the play blood symbolizes treachery and treason, and towards the end of the play blood symbolizes the guilt and grief of both MacBeth and Lady MacBeth. Bloodshed also gives one power and with power there comes great responsibility. "Macbeth" is a play stained in blood that has many symbolic measures to it.
The first reference of blood is one of honor, and occurs when Duncan sees the injured sergeant and says, "What bloody man is that?"(Act 1 Sc 2 line 1) This is symbolic of the brave fighter who has been injured in a valiant battle for his country. In the next passage, in which the sergeant says, "Which smok'd with bloody execution"(Act 1 Sc 2 line 18), he is referring to Macbeth's braveness in which his sword is covered in the hot blood of the enemy. Blood is used in these passages to identify honor and courage, it separates the good from the bad, and it also gives the reader a view of how the shedding of blood will be used often to identify certain characteristics.
After these few references to honor, the symbol of blood changes to show a theme of treachery and treason.