Answer: Macbeth’s vision of Banquo’s ghost demonstrates his state of mind slipping through his grasp, as he comes face to face with the repercussions of his actions. Although Macbeth did not kill Banquo by his own hand, he used his position of power to have others do his dirty work for him, causing him to feel an immense sense of guilt. His guilt plays a large factor in his state of mind, causing him to slowly slip into insanity, as he demonstrates internal conflict with himself.