What are the main themes of William Shakespeare's Macbeth?

Perhaps the greatest of Shakespeare's tragedies, Macbeth focuses on three primary themes.

POWER & AMBITION.  Both Macbeth and Lady Macbeth become enamored with the idea of power and each respond by committing terrible crimes. Although Macbeth desires the throne, it is his wife's ambitious prodding that prompts him to kill his king. One crime begets another until Macbeth falls prey to a more powerful foe.

GUILT & FEAR.  Following each misdeed, Macbeth and his wife become overwhelmed with guilt, facing this consequence by committing even more crimes. But instead of a guilty conscience, Macbeth views his psychological reaction as fear instead. Lady Macbeth, meanwhile, understands the guilt that plagues her, but she attempts to deny it.

NATURAL VS. SUPERNATURAL.  Macbeth encompasses the supernatural world, beginning with the three witches who prophesy both "foul and fair." Reality is often confused with prophecy, and an aura of evil follows the two main characters. Both Macbeth and Lady Macbeth fall victim to the madness that follows their many unnatural acts.