In Act V, scene v of Shakespeare's Macbeth, identify Macbeth's realization about the prophecies, and how it relates to the play's central theme.
Recall that Hecate, Queen of the Witches, was angry with the weird sisters because, among other things, they had not taught Macbeth to respect their power, and more than that, they had not tricked him into completely giving himself over to their power. She plans, then, to provide him with misleading prophecies that, when taken at face value, will lead him to his destruction by giving him a false sense of security (which she says is man's greatest enemy).
When Malcolm begins to move in for his attack, Macbeth scoffs at those who desert his own forces because he believes...no one born of woman can harm him, that he needs to beware of Macduff, and that he cannot be defeated until Birnam Wood moves to Dunsinane Hill.
However, when a messenger reports that it looked like the woods moved (when it was actually Malcolm's men camouflaged with branches), Macbeth realizes that the witches were playing "word games," practicing "doublespeak" or double-talk.
By the time Macduff arrives, and admits his was a cesarean birth:
Despair they charm,
And let the angel whom thou still has served
Tell thee Macduff was from his mother's womb
Untimely ripped... (13-15)
...Macbeth clearly realizes that he has been tricked. One of the few things to admire about this tyrant at the end of the play is that he does not cower, but faces Macduff like a man. Ironically, the Thane of Cawdor, whose title and lands were conferred on Macbeth after the Thane was convicted of treason, also went nobly to his death.
The central theme I see in this play (though there are other secondary themes as well) comes from the witches during their first set of prophecies for Macbeth:
Fair is foul, and foul is fair... (I, i, 11)
Translated, this means, generally, that what looks good can sometimes be bad, and what looks bad can sometimes be good.
For example, Macbeth looks like an honorable man at the start, but hides his vaulting ambition so no one realizes at first that he could kill the King. On the other hand, when Malcolm and Donalbain flee after their father's murder, the "rumor" spreads that they are guilty of the King's death. The truth is that they are afraid they will be killed also, as Malcolm has just been named heir to the throne.
With regard to the witches' second set of predictions, they sound good: Macbeth believes he is invincible, however, they are inaccurate and they ultimately thwart Macbeth's attempts to hold onto the throne, and lead to his eventual death.
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