It would seem that Shakespeare did not to present Macbeth as an out-and-out villain like Richard III but as a basically decent man who was led astray by his own ambition as well as by the supernatural powers of the Weird Sisters and the relentless pressures of his own ambitious wife. When Macbeth encounters the three witches for the first time, they seem to be predicting the very crime he has been considering. This makes it seem to him as if his future is predetermined and unavoidable. His wife uses every tactic she can think of to pressure him into killing Duncan. She tells him he is unmanly if he doesn't go through with it and that she won't love him because he will have shown that he doesn't love her. Macbeth consults the Weird Sisters two more times, and both times they assure him that his future is already determined. They also assure him that no man born of woman can overcome him and that his reign is secure unless Birnam Wood were to move to Dunsinane Castle. So Macbeth is partly responsible for his own downfall but would most likely not have gone ahead with his plans if he hadn't had the assurances and encouragement of the Weird Sisters and of Lady Macbeth.