That Macbeth is basically a noble person who allows himself to be manipulated into performing acts, which are contrary to his true nature can be seen as a true statement at the beginning of the play when we are first introduced to Macbeth because he appears to be a noble general for the King's army. However, as the play progresses we see that he is an easily manipulated person who is willing to do whatever it takes to get what he wants.
The most significant points in the play are when the witches tell Macbeth several prophecies about his future. It is these prophecies that turn Macbeth into the evil person that he is at the time he dies. After hearing the first three prophecies telling him that he will be the thane of Glamis, the thane of Cawdor and also the King, Macbeth is more than willing to accept these, as one of them is already true.
Macbeth is the thane of Glamis. Soon after he is visited by Ross and Angus, who inform him, he is now the thane of Cawdor. "Two truths are told...This supernatural soliciting cannot be ill"(1:3:137). At the time he also believes that these prophecies will come true in their own time and he should just live his life as normal, knowing what is waiting for him in the future. "If chance will have me king, why, chance may crown me, without my stir."(1:3:154).
This idea is immediately rejected when Macbeth informs his wife of his encounter with the witches. She believes that Macbeth must do whatever it takes to fulfil these prophecies, and it is she that is the driving force behind Macbeth's eventual madness. To her, the prophecies must be fulfilled now, not in the future. "To catch the nearest way:...