Throughout Macbeth, the nature of evil and human corruption are explored. Humanity is defined by good, but evil stems from the human heart because it is the opposite of good. A human being is not the initiator of supernatural or unnatural forces, but their agents.
D I know this because I read the book as a child. Most of the book was a blur except for Judd's harsh cruelty. That's what captured me the most. Almost all his animals were so violent. All except Shiloh.