how does ambition drive the play forward?

Ambition and temptation both play a key factor in Macbeth and Lady Macbeth’s decision to kill Duncan. Macbeth possesses enough self-awareness to realize the dangers of overzealous ambition: “I have no spur / To prick the sides of my intent, but only / Vaulting ambition which o’erleaps itself / And falls on th’other” (25-28). And yet, the temptation to carry out the witches' prophecy is ultimately too strong for Macbeth to curb his ambition. Shakespeare also uses other characters to bring out Macbeth's issues of ambition. Shakespeare uses Banquo as a character foil to Macbeth. While Macbeth is rash and obsessive, Banquo is measured and wise. Macduff is also an effective foil to Macbeth. Macduff personifies the traits of loyalty and the limits of loyalty. Macduff seeks to serve a righteous leader while Macbeth is only concerned about his own ambition and power. L. Macbeth certainly uses manipulation to expose Macbeth's early flaws.