These stages in Macbeth's development relate to his being one of Shakespeare's tragic heroes. As the play begins, he is one of King Duncan's generals, noted for his fierce courage. In his battle against Duncan's enemies, he fights so furiously and valiantly that Duncan rewards him by making him the Thane of Cawdor.
Macbeth's ambition is aroused by the witches' prophecies, and once he becomes Thane of Cawdor, he sets out to gain the throne of Scotland. In order to achieve his political ambitions, he murders a sleeping King Duncan and his attendants. Once he has become King of Scotland, Macbeth orders the subsequent murders of Banquo, Banquo's son Fleance, and Macduff's entire family, including his wife and young son. Of these, only Fleance escapes with his life. These are not the acts of a heroic warrior. These are the acts of a bloodthirsty tyrant, which is what Macbeth has become.
In the play's conclusion, even though he is outnumbered and defeated, Macbeth chooses to die in battle rather than endure the humiliation of surrender. As he faces Macduff, he declares, "Lay on, Macduff; /And damned be him that first cries 'Hold, enough!'" Thus the last view of Macbeth is one of courage in battle, a glimpse of his former self.