Macbeth, of course, is highly concerned with the issue of good versus evil, almost as much as the conflict between fate, the supernatural, and free will. To pull out one thread that Shakespeare develops, it could be argued that the most important point raised about morality is this: Unchecked ambition can destroy everything that is good about a man (or woman,) causing him to commit unspeakable acts. Macbeth is portrayed in the play's opening scenes as a worthy man, violent to be sure, but ultimately a faithful kinsman and vassal to Duncan. Yet is ambition is piqued by his encounter with the witches, and with significant help from his wife, he ultimately murders the king, a deed for which he admits he has no motive but his own "vaulting ambition." He goes on to murder Banquo because of the witches' prediction that his progeny will sit on the throne of Scotland. By the end of the play, Macbeth is a monster, showing no remorse for the deeds he has committed and ultimately bereft of any sense of morality. His ambition has eaten away all that was good about him.