Act 1, Scene 3

Two truths are told
As happy prologues to the swelling act
Of th’imperial theme

Macbeth speaks these lines as he realizes that the witches’ prophecy (that he will be Thane of Cawdor) has come true. He immediately starts to wonder whether this means that their third prophecy (that he will become king) will also come to fruition. The eagerness with which he turns to this idea suggests that he finds the possibility appealing, even though he also realizes he would have to commit a terrible and violent act to achieve the position. These lines hint at Macbeth’s ambition and foreshadow his later actions even though, at this point in the play, he seems to refuse to consider acting upon it.

 

Act 1, Scene 5

Thou wouldst be great
Art not without ambition, but without
The illness should attend it

In Act 1, Scene 5, Lady Macbeth speaks these lines as she reflects on her husband’s character. She knows that Macbeth is capable of ambitious dreams, but she thinks that he is unwilling to behave ruthlessly enough to achieve those dreams. These lines reflect Lady Macbeth’s own philosophy of power, in which only individuals who are willing to set their morality aside will rise to greatness. They also show that she is a sound judge of character, and understands her husband very well.

 

Act 1, Scene 7

I have no spur
To prick the sides of my intent, but only
Vaulting ambition, which o’erleaps itself
And falls on th’other

Macbeth speaks these lines as he starts to doubt his plan to murder Duncan. He uses a complicated metaphor that compares his experience to horse-riding. He describes being unable to motivate himself to act by likening himself to a rider who cannot use his spurs to motivate his horse to go faster. The one thing he does have is ambition, which he compares to a horse and rider who overestimate their ability to leap over an obstacle, and end up falling down. The passage describes the tension between Macbeth’s dangerous ambition and his reluctance to move ahead with his plan.

Act 3, Scene 1

To be thus is nothing,
But to be safely thus. Our fears in Banquo
Stick deep, and in his royalty of nature 
Reigns that which would be feared. 'Tis much he dares,
And to that dauntless temper of his mind
He hath a wisdom that doth guide his valor
To act in safety. There is none but he
Whose being I do fear...

When Macbeth speaks these lines in Act 3, Scene 1, he has become king, as he planned, but he continues to feel restless and insecure.  In this mindset, Macbeth ruminates anxiously on his friend Banquo’s heroic traits, thinking of him as a threat to his reign. This quote reveals how Macbeth succumbing to his ambition and murdering Duncan has not brought him peace but rather has just left him more paranoid and anxious. It also shows how Macbeth’s first violent action sets off a chain reaction of violence for Macbeth to maintain his hold on the power he has gained.