Blood
Blood represents the violence and guilt that stain Macbeth and Lady Macbeth after they commit the murders of Duncan, Banquo, and Macduff's family. Blood also symbolizes the natural order that is disrupted by Macbeth's regicide, as Duncan is described as having "silver skin laced with his golden blood" (2.3.109). Macbeth and Lady Macbeth try to wash away the blood from their hands, but they cannot escape the consequences of their actions. As Lady Macbeth says, "What, will these hands ne'er be clean?" (5.1.45).
The dagger
The dagger that Macbeth sees before he kills Duncan is a symbol of his inner conflict and his temptation to commit evil. The dagger is "a false creation, / Proceeding from the heat-oppressed brain" (2.1.38-39), but it also points the way to Duncan's chamber, as if inviting Macbeth to murder him. The dagger is also covered with blood, foreshadowing the deed that Macbeth is about to do and the guilt that will haunt him afterwards.
The witches
The witches are a symbol of the supernatural forces that influence Macbeth's fate and his downfall. They prophesy that Macbeth will become the king of Scotland, but they also warn him to "beware Macduff" (4.1.71) and that "none of woman born / Shall harm Macbeth" (4.1.80-81). The witches' words are ambiguous and paradoxical, as they often contain a hidden truth or a twist of fate. For example, Macduff was not technically "of woman born" because he was "from his mother's womb / Untimely ripped" (5.8.15-16). The witches also represent the dark side of human nature, as they appeal to Macbeth's ambition and manipulate him to do evil.
The weather
The weather in the play reflects the mood and the moral state of the characters and the events. For instance, the night of Duncan's murder is marked by thunder, lightning, and "strange screams of death" (2.3.54). The weather also signifies the disruption of the natural order caused by Macbeth's usurpation of the throne, as Ross observes, "Thou seest, the heavens, as troubled with man's act, / Threaten his bloody stage" (4.2.4-5). The weather also foreshadows the outcome of the play, as Macbeth's final battle with Macduff is accompanied by a storm and a darkened sun.
