The motor that drives the tragedy of Shakespeare's "Macbeth" is the lead character's ambition. It is his primary character flaw and the trait that causes this brave soldier to murder his way to power.
Early on in the famous play, King Duncan hears of Macbeth's heroics at war and bestows the title Thane of Cawdor on him. The current Thane of Cawdor has been deemed a traitor and the king orders him to be killed. When Macbeth is made Thane of Cawdor, he believes that the kingship is not far off in his future. He writes a letter to his wife announcing the prophecies, and it is actually Lady Macbeth who fans the flames of ambition as the play progresses.
The two conspire to kill King Duncan so that Macbeth can ascend to the throne. Despite his initial reservations about the plan, Macbeth agrees, and, sure enough, he is named king after Duncan's death. Everything that follows is simply the repercussion of Macbeth's unbridled ambition. Both he and Lady Macbeth are plagued by visions of their wicked deeds, which eventually drive them insane.
When Macbeth first appears at the start of the play, he is brave, honorable, and moral-qualities that he sheds as the play develops. He comes on the scene soon after a battle, where an injured soldier reports Macbeth's heroic deeds and famously labels him “brave Macbeth”:
"For brave Macbeth-well he deserves that name-
Disdaining Fortune, with his brandish'd steel,
Which smoked with bloody execution,
Like valour's minion carved out his passage
Till he faced the slave."
(Act 1, Scene 2)
Macbeth is presented as a man of action who steps up when he is needed, and a man of kindness and love when he is away from the battlefield. His wife, Lady Macbeth, adores him for his loving nature:
"Yet do I fear thy nature;
It is too full o' th' milk of human kindness
To catch the nearest way. Thou wouldst be great,
Art not without ambition, but without
The illness should attend it."
(Act 1, Scene 5)
An encounter with the three witches changes everything. Their premonition that Macbeth “shalt be king hereafter” triggers his ambition-and leads to murderous consequences.
Macbeth makes clear that ambition drives his actions, stating as early as Act 1 that his sense of ambition is “vaulting”:
"I have no spur
To prick the sides only
Vaulting ambition, which oerleaps itself
And falls on the other."
(Act 1, Scene 7)
When Macbeth makes plans to murder King Duncan, his moral code is still evident-but it is beginning to be corrupted by his ambition. In this quote, the reader can see Macbeth struggling with the evil he is about to commit:
"My thought, whose murder yet is but fantastical,
Shakes so my single state of man that function
Is smother'd in surmise."
(Act 1, Scene 3)
Later in the same scene, he says:
"Why do I yield to that suggestion
Whose horrid image doth unfix my hair,
And make my seated heart knock at my ribs,
Against the use of nature?"
(Act 1, Scene 3)
But, as was made apparent at the beginning of the play, Macbeth is a man of action, and this vice supersedes his moral conscience. It is this trait that enables his ambitious desires.
As his character develops throughout the play, action eclipses Macbeth's morals. With each murder, his moral conscience is suppressed, and he never struggles with subsequent murders as much as he does with killing Duncan. By the end of the play, Macbeth kills Lady Macduff and her children without hesitation.
Shakespeare does not let Macbeth get off too lightly. Before long, he is plagued with guilt: Macbeth starts hallucinating; he sees the ghost of murdered Banquo, and he hears voices:
"Methought I heard a voice cry 'Sleep no more!
Macbeth does murder sleep.'"
(Act 2, Scene 1)
This quote reflects the fact that Macbeth murdered Duncan in his sleep. The voices are nothing more than Macbeth's moral conscience seeping through, no longer able to be suppressed.
Macbeth also hallucinates the murder weapons, creating one of the play's most famous quotes:
"Is this a dagger which I see before me,
The handle toward my hand?"
(Act 2, Scene 1)
In the same act, Ross, Macduff's cousin, sees right through Macbeth's unbridled ambition and predicts where it will lead: to Macbeth becoming king.
"'Gainst nature still!
Thriftless ambition, that will ravin up
Thine own lives' means! Then 'tis most like
The sovereignty will fall upon Macbeth."
(Act 2, Scene 4)
Near the end of the play, the audience catches a glimpse of the brave soldier who appeared at the beginning. In one of Shakespeare's most beautiful speeches, Macbeth admits that he is short on time. The armies have amassed outside the castle and there is no way he can win, but he does what any man of action would do: fight.
In this speech, Macbeth realizes that time ticks on regardless and that his actions will be lost to time:
"Tomorrow and tomorrow and tomorrow
Creeps in this petty pace from day to day
To the last syllable of recorded time
And all our yesterdays have lighted fools
The way to dusty death."
(Act 5, Scene 5)
Macbeth seems to realize in this speech the cost of his unchecked ambition. But it is too late: There is no reversing the consequences of his evil opportunism.