What ideas does Shakespeare develop regarding the acceptable limits of ambition?

A paper that analyzes Shakespeare's development of ideas regarding the acceptable limits of ambition could begin with the contrasting reactions of Banquo and Macbeth when they hear the Weird Sisters' initial prophecies. Banquo is suspicious, while Macbeth's interest is piqued in a more profound way. It seems that by nature Macbeth is more ambitious than Banquo; this is why the goading of his wife is so quickly effective. The seeds of ambition are already within him. This idea is further supported by examining Macbeth's exploits in battle; he is unafraid of brutality and performs with zeal the execution of Macdonwald in service to his king and country.
A message in the play may be that the acceptable limits of ambition are inextricably linked to the cause to which characters align themselves. The actions of Macbeth and Lady Macbeth are unacceptable because they violate the Great Chain of Being. They commit regicide and then other murders to maintain their unjust rule over Scotland. The actions of Malcolm and Macduff lay within acceptable limits because they seek to restore the Great Chain of Being. Malcolm is the legitimate heir to Scotland's throne and Macduff consistently displays loyalty to the legitimate king and his country. Their ambitions to attack Macbeth's forces and kill Macbeth are acceptable because their cause is just. Shakespeare draws a distinction between state-sanctioned violence and murder for personal gain.