Quote 7
MACBETH [aside]
The Prince of Cumberland! That is a step
On which I must fall down, or else o'erleap,
For in my way it lies. Stars, hide your fires;
Let not light see my black and deep desires.
The eye wink at the hand; yet let that be
Which the eye fears, when it is done, to see. (1.4.55-60)
Macbeth describes his ambition as being "black and deep desires," which makes it sound… well, wrong. Is ambition okay in any context, or are we all supposed to let fate and chance toss us around?
Quote 8
MACBETH
I have no spur
To prick the sides of my intent, but only
Vaulting ambition, which o'erleaps itself
And falls on the other— (1.7.25-28)
Time to be real: when Macbeth is honest with himself, he admits that there's no good reason to kill Duncan, because Duncan is perfectly good at this whole king-business. Macbeth just wants that power for himself.
Quote 9
MACBETH
For mine own good
All causes shall give way. I am in blood
Stepped in so far that, should I wade no more,
Returning were as tedious as go o'er. (3.4.167-170)
In case we still had some lingering doubts, Macbeth clears that up for us: he's doing all this "For mine own good." Great. We'll be sure not to ask him for any favors, then.