Why is the play "Macbeth" so concerned with images of "fair" and "foul"?

The equivocal words "fair" and "foul" echo throughout "Macbeth", from the very beginning of the play, when the witches say; "Fair is foul, and foul is fair, / Hover through the fog and filthy air." Throughout the play, the contrast between fair and foul creates dramatic tension. It links the witches to Macbeth, represents Macbeth's inner moral conflict, and shows the development of Macbeth's and Lady Macbeth's characters. Thus, Shakespeare uses this conflict between foul and …

…words "fair" and "foul" recur, and many aspects of the play are both fair and foul. Shakespeare uses the words "fair" and "foul" many times during the play to describe contrasts between them and many facets which are both fair and foul, and to create a sense of disorder. He uses the ambiguity of the words fair and foul to create great theatrical effect, and depict the tension between the forces of good and evil.