It might be reasonable to say that Lady Macbeth has contributed a great deal to Macbeth's general sense of insecurity but little to the specific insecurities which led him to act in a tyrannical manner after becoming king. She makes him feel that he has to be decisive and violent in order to be a real man, but the murder of Banquo and the assault on Macduff's castle seem to be entirely Macbeth's idea. These atrocities are the result of insecurities which arise directly from the murder of Duncan.

It seems reasonable to suppose that if Macbeth had not begun his reign with murder, the noble elements in his nature might have prevailed. He would not then have been fearful that his crime might be discovered or that his thanes were disloyal. In this case, his reign would certainly have been longer and more peaceful.