The use and abuse of power is an important theme in 'Macbeth'. We see the supernatural power of the witches, the political power of the monarchy and the physical power of the warrior.
The witches are the first powerful figures we meet in the play. They use suggestion and the negative characteristics of their victims to destroy them and others. Macbeth's ambition, which has brought him great success and reward when used justly, is proved to be his downfall when distorted by the witches into violent pursuit of an 'unnatural' goal ( Macbeth was not the true heir to the throne as decreed by the Divine Right of Kings). Their power is in what they make others do, and their strength is in their psychological awareness of the deepest desires of man (and woman). Macbeth is driven by their words and images to kill the king-
Is this a dagger which I see before me,
The handle toward my hand? Come, let me clutch thee.
I have thee not, and yet I see thee still.
Art thou not, fatal vision, sensible
To feeling as to sight? Or art thou but
A dagger of the mind, a false creation,
Proceeding from the heat-oppressed brain?
King Duncan is a fair and benevolent king. He rewards Macbeth for his valiant defence of the realm on the battlefield, and punishes the first Thane of Cawdor for his treachery. He uses his powers justly, and, though killed, is justly avenged in the deaths of Macbeth and Lady Macbeth.
Macbeth proves to be a paranoid and vengeful king-
Tyrant, show thy face!
He is afraid for his position and can only kill to comfort himself. His action in taking the life of the king is an abuse of his power as host and subject, and he pays with his life and his sanity. The 'valiant' soldier becomes a 'dead butcher'.
Lady Macbeth calls upon the powers of evil to give her strength to kill the king. She has no right to command such forces, and her demands are punished with her madness and death. She controls her husband, manipulating him in to killing the king as much as the witches do. Her alliegance with dark forces has dark consequences.