The Corruption of Ambition
We see evidence throughout the play that Macbeth is by nature a brave soldier and one who adheres to duty. However, once ambition in the form of the witches’s prophecy and the influence of his wife begin to overtake his natural tendencies, he tends toward murder and violent usurpation. Lady Macbeth also says many things throughout the play which demonstrate that her motivations are more honest than her actions. Yet, the corrupting influence of ambition and the love of power undermine her as much as Macbeth. Both characters become undone both internally and externally. They are punished by their own sense of guilt and Macbeth, at least, is punished with death for his crimes.
Natural and Supernatural
The supernatural is obvious in the witches. Their power and influence is entirely the stuff of magic. Banquo’s ghost also figures as an image of the supernatural. All of these influences spur the violence and crime throughout the play. At the same time, Macbeth’s murder of the king and of an entire family are acts against nature. As the king is the natural head of the nation, so it is a crime against nature to kill him and these types of crimes are monstrous. Though the witches may appear as supernatural monsters, it is Macbeth who becomes the monster by going against the natural order. Lady Macbeth also oversteps her nature. As a female character in Elizabethan England, she goes against nature when she advises and directs her husband to commit his crimes. She defies her natural role as a subservient woman. Her subsequent illness and suicide are the penalty for defying her nature.
Revenge and Remorse
Once Macbeth begins his crimes, each subsequent crime creates the justification for more crime. He feels at least partially justified in his murder of the king because he believes he has a right to the throne. But as soon as he commits the crime, he is stricken with remorse. The dual burden of remorse and fear of revenge leads him to commit more murders. Macbeth is justifiably killed in the end but only after there is clear evidence of justified revenge.