Royalty Should Only be Earned and Never Stolen
I think this is the theme of the book is that royalty should only be earned and never stolen. There are three examples of this; the first example of this theme is Banquo's children. Obviously, because the are not in the royal line, yet the will some day rule the kingdom, they must have somehow earned the rank of King. We know that they earned the rank, because if the stole it, he would never be able to have so many royal desendents.
The second example is King Duncan. He is said to be a peaceful king. We can tell this because he does not engage or even watch the battle that Macbeth and Banquo are in. His rule seemed to be fairly successful, because all of his lords love him. If he was not successful, many of the lords would probably be thinking of doing what Macbeth actually did.
Finally, the third example is Macbeth, himself. Obviously, Macbeth only was king because he lied and sinned to get onto the throne. He first killed Duncan, then blamed it on the gaurds, and then finally planned to kill Duncan's sons. Even though he tries to keep his dark plans a secret, eventually the kingdom guests what he did, and they rebel against him. His rule was never prosperous, because even before the revolution, both he and Lady Macbeth were going insane from the sins the have committed. This is why I think the theme of Macbeth is that royalty should only be earned and never be stolen.
