Ultimately, everyone must take responsibility for their actions. The witches certainly prophesied that he would be king, but they did not tell him that he had to murder King Duncan in order to become king. If he trusted their prophesies (as he seems to have done), he could have waited for these prophesies to come true without trying to make them come true. "Chance may make me king without my stir". However, the moment he hears their prophesy, the thought of assassination crosses his mind: "whose horrid intent makes my seated heart knock. . . ". Later on he seems to try to fight against this terrible desire. However, he had already communicated the prophesy to Lady Macbeth, and she was not willing to let him forget about it. Thus his feeble attempt to forget about murder is brushed aside by his wife who asks why he chose to tell her about it if he was going to not do anything about it. When Lady Macbeth exhorts him to keep to his purpose, he gives in without much of a fight. Is there, therefore, something hypocritical in his attempt to fight against his darker desires? Every other murder is planned and executed by Macbeth alone. Lady Macbeth has no share in it. Perhaps she becomes insane towards the end of the play, because she realized that her ambitions have helped transform her husband into a monster. So though the witches' prophesy and Lady Macbeth helped persuade Macbeth, ultimately Macbeth is responsible for his own actions, which culminated in his downfall.