Quote 7
LADY MACBETH
[...] I have given suck, and know
How tender 'tis to love the babe that milks me.
I would, while it was smiling in my face,
Have plucked my nipple from his boneless gums
And dashed the brains out, had I so sworn as you
Have done to this. (1.7.62-67)
Here, Lady Macbeth takes breastfeeding —one of the fundamental biological traits of women as the Early Modern period saw it—makes it monstrous. She says that she's so good at keeping promises that she would actually kill a nursing child if she'd promised to do it. What's funny (not funny ha-ha) to us is that Macbeth has promised to kill his king, i.e. father figure; Lady Macbeth is talking about killing her child. Hmmm.
Quote 8
LADY MACBETH
Are you a man?
[…]
O, proper stuff!
This is the very painting of your fear.
This is the air-drawn dagger which you said
Led you to Duncan. O, these flaws and starts,
Impostors to true fear, would well become
A woman's story at a winter's fire,
Authorized by her grandam. Shame itself!
Why do you make such faces? When all's done,
You look but on a stool. (3.4.70;73-81)
In other words, Lady Macbeth is (yet again) telling Macbeth that he's acting like a girl—or, in this case, an old women. Honestly, we're a little surprised that—since this is Shakespeare and all —he didn't just up and kill her instead of Duncan.
Quote 9
LADY MACBETH
[…] The raven himself is hoarse
That croaks the fatal entrance of Duncan
Under my battlements. Come, you spirits
That tend on mortal thoughts, unsex me here,
And fill me from the crown to the toe top-full
Of direst cruelty. Make thick my blood.
Stop up th' access and passage to remorse,
That no compunctious visitings of nature
Shake my fell purpose, nor keep peace between
Th' effect and it. Come to my woman's breasts
And take my milk for gall, you murdering ministers,
Wherever in your sightless substances
You wait on nature's mischief. Come, thick night,
And pall thee in the dunnest smoke of hell,
That my keen knife see not the wound it makes,
Nor heaven peep through the blanket of the dark
To cry "Hold, hold!" (1.5.45-61)
Does Lady Macbeth actually believe she's calling on spirits? In other words, is she herself a witch of some kind? Or is this all just a metaphor for evil thoughts? It matters, because it affects how we read her madness at the end. Is she being driven crazy by these spirits, or is she having a psychotic break from realizing how awful her actions were?