Explode the quote, "Fair is foul, and foul is fair. Hover through the fog and filthy air."
¬repetitive "f" sounds aggressive and conveys the violence of the witches desires.
¬becoming king would've been "fair" if he'd waited, but he was impatient and ambitious so he made it "foul"
¬ CONTEXT: The King at the time, James I, wrote a book stating all magic was evil - this chant sounds almost like a magical spell, and the audience would fear it.
¬repetition of "fair" and "foul" suggests the two ideas are interchangeable, emphasised further by the definite "is".
¬imagery reinforces the idea of a distorted reality. The fog and filthy air symbolize a world where truth is obscured, and the characters struggle to see clearly.