Final answer:
The line 'Fair is foul, and foul is fair' in Shakespeare's Macbeth is a paradox that sets the tone for the play, indicating that the boundaries between good and evil are blurred and foreshadowing the chaos that ensues from Macbeth's actions.
Step-by-step explanation:
The line "Fair is foul, and foul is fair" from Macbeth, spoken by the witches, establishes a tone of ambiguity and foreboding at the very outset of the play. It suggests that appearances can be deceptive, and sets up a world where the boundaries between good and evil, or reality and illusion, are blurred. This paradox does not suggest that good things will happen to good people, but rather foreshadows a world in which moral absolutes are subverted, leading to chaos and disorder.
Macbeth's encounter with the witches plants the seeds of his tragic downfall. Their prophecy is double-edged; it is both a prediction of Macbeth's rise to power and an implicit hint at the unnatural means by which he will obtain it. This paradox creates a sense of unease and suggests that the events to follow will challenge the natural order of things, contributing to the play’s dark and ominous atmost.