In Macbeth, how does Shakespeare characterize the witches and what is their thematic significance?

The memorable Three Weird Sisters in Shakespeare's Macbeth perform a significant role throughout the play by manipulating Macbeth to make rash decisions which lead to his tragic downfall. In the opening scene of the play, Shakespeare introduces the audience to the Three Weird Sisters, who discuss meeting Macbeth when the battle is over before delivering their famous line "Fair is foul, and foul is fair" (Act I, Scene 1, line 12).

Thematically, this statement introduces the...

The memorable Three Weird Sisters in Shakespeare's Macbeth perform a significant role throughout the play by manipulating Macbeth to make rash decisions which lead to his tragic downfall. In the opening scene of the play, Shakespeare introduces the audience to the Three Weird Sisters, who discuss meeting Macbeth when the battle is over before delivering their famous line "Fair is foul, and foul is fair" (Act I, Scene 1, line 12).

Thematically, this statement introduces the concept that nothing is what it seems, which is significant to the plot of the play. Continually, Macbeth and other characters will be fooled into believing that things are opposite of their true nature. In Act I, Scene 3, the Three Weird Sisters discuss how they will avenge a woman who refused to share her chestnuts. They mention that they will influence the winds to make her husband's journey across the sea difficult. Throughout this conversation, Shakespeare indirectly characterizes the witches as being petty and vengeful. The fact that they have the power to influence the weather, yet lack the ability to directly harm or kill the woman's husband suggests that their control over people's fates is limited and ambiguous.

Later in the scene, Macbeth and Banquo meet the Weird Sisters and are repulsed by their appearance. Banquo comments,

What are these so withered and so wild in their attire, that look not like th' inhabitants o' th' Earth, and yet are on ’t?—Live you? Or are you aught that man may question? You seem to understand me, by each at once her choppy finger laying upon her skinny lips. You should be women, and yet your beards forbid me to interpret that you are so (Act I, Scene 3, lines 39-48).

The witches proceed to prophesy about Macbeth's eventual kingship and Banquo's descendants before disappearing into thin air. During their encounter, Shakespeare characterizes the Three Weird Sisters as grotesque, evil characters who use their knowledge of the future to ruin Macbeth.

In Act IV, Scene 1, the Three Weird Sisters concoct a charm that will negatively affect Macbeth's ability to interpret their prophecy accurately by using various animal parts and crude ingredients as they chant, "Double, double toil and trouble, Fire burn and cauldron bubble" (Act IV, Scene 1, lines 20-21).

When Macbeth enters the scene and demands to know his future, the witches conjure three apparitions that give Macbeth a false sense of confidence. The nature of the witches is nefarious, and their prophecies are ominous. Their function is to the set the tone of the play and confuse Macbeth into making terrible decisions that will result in his demise. Overall, Shakespeare characterizes the Three Weird Sisters as wicked, vengeful, grotesque witches whose sole purpose is to cause chaos and trouble.