What feeds our ambitions? Is it our decisions to feed our desires? Or is it only our greed and selfishness? Ambition helps the fuel some of the worst and best ideas of people. Those that want to see us succeed can usually lead on our ambitions. They can lead us to make the decisions that are sometimes for the better, or not. In Macbeths case, his wife and the witches helped Macbeth with his decision to kill Duncan. Their predictions and enthusiasm helped him to make the decision.
At the beginning of the play, Macbeth and Banquo meet the witches they tell him of his future: "All hail Macbeth! Hail to thee thane of Glamis!" , "All hail Macbeth! Hail to thee thane of Cawdor!" , "All hail Macbeth! That shalt be king hereafter!" After hearing these, Macbeth grabs enough reality to realize that he is not the Thane of Cawdor, so then the witches must be lying. But moments later, a strange man rides up to Macbeth and presents him the medallion of the Thane of Cawdor. He realizes that what the witches say must be true. He has the temptation to speed up the process of becoming king by killing Duncan.
These predictions that the witches made helped to fuel Macbeths ambition. Macbeth is rethinking his idea to do so, but as he is, Lady Macbeth comes to him and convinces him it is the best. He was still reluctant, but his wife kept pursuing him. In the end, with the witches prophecies and his wifes encouragement, he decides it is time. If you read the story closely, you would see that the evil desires are mostly Lady Macbeths and that she is more evil, and devilish. She has the keen, skilled mind of a murderer. As Macbeth says: "We will proceed no further in this business". Lady Macbeth fights back with: "And live a coward in thine own esteem".
His ambition was further pushed when he had sent those men to murder his best friend, Banquo. Again as the witches had predicted his becoming king and Thane of Cawdor, he believed in them when they said the descendants of Banquo would become kings. This thought arouses when the witches say this: "Thou shalt get kings, though thou be none". This feeds his fear and ambition to kill Banquo as well as his son. This irrational thinking shows the signs that his ambition is getting to him and is too much. He is willing to kill his best friend to make sure the predictions do not come true. He is determined to make sure the crown stays in his family, and in no other. That act is the first that leads to the downfall of the Mighty King. This act is the start of his downfall.
So if the question of ambition is whether it is a correct sense of determination or not, it sometimes can be, but not in Macbeths case. It showed that Macbeths ambitions were purely greedy selfish ones that led to his downfall, defeat, and eventually death. When our ambitions are leading to success, it is greatly useful. If we use ambition for our own personal gain and greed, you end up getting it all in your face at the end, like our protagonist, Macbeth. Ambition can most definitely control and drive a person, but there are certain extents. You do not take advantage of these, and then ambition is amazingly pure and good.