Conclusion: In the first three scenes of Macbeth, there are mainly two types of blood, and blood symbolizes both humanity and its opposite(negatively associated) emotions, such as guilt and pain. One of the first mentioned aspects of blood is the ability to feel emotion in itself. In act 1, Lady Macbeth asks for her blood to thicken, and for this to guard her against negative thoughts and strong emotions. This means that here, blood, literally, symbolizes humanity and the humans' ability to feel emotion. As the play moves on, blood starts to symbolize guilt. In act 3, Macbeth laments that he is stepped in too much blood to go back(i.e. too guilty of bad deeds). Likewise, blood is mentioned in many places in place of guilt: after murdering Duncan, Macbeth talks about water washing this "blood" from his hands(for something to abolve him of his guilt). Likewise, Lady Macbeth talks about how easy it would be to wash 'blood from her hands'- literally, the guilt of her murdering Duncan.
