In Shakespeare' Macbeth, Lady Macbeth also delivers a soliloquy that allows us to look deep into the heart of the woman who drives Macbeth to murder Duncan—his King, his friend, his cousin, and his houseguest (a terrible act in those days).
Lady Macbeth notes the presence of a raven, a bird associated with death, as it "croaks" Duncan's approach, which Lady Macbeth has already decided will be his last entrance, to her castle. Here she calls on the dark spirits to change her so that she may be as hard and vicious as necessary to do what must be done to kill the King. She wants to no longer have the characteristics of a woman ("unsex me here") and make her capable of great cruelty, something that does not (according to Shakespeare) come naturally to a woman (the "gentler" sex). She asks that her blood be thickened, and the passage to conscience and remorse within her be blocked so she feels no guilt, so nothing stands between her and what she intends to do.
The raven himself is hoarse
That croaks the fatal entrance of Duncan (40)
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 the access and passage to remorse,(45)
That no compunctious visitings of nature
Shake my fell purpose nor keep peace between
The effect and it!
She then asks the spirits of darkness ("murdering ministers") that lend strength to "human mischief" to make her mother's milk, something associated with love and nurturing of a child, be made poisonous ("gall").
Come to my woman's breasts,
And take my milk for gall, you murdering ministers,
Wherever in your sightless substances (50)
You wait on nature's mischief!
Next, Lady Macbeth addresses the cover of night, asking it to bring the dark mists of hell around her so that (personifying her weapon) her knife does not "see" the wound it intends to make in the good, "God-chosen" King; to make it dark enough that even heaven cannot see what she intends to do to and (personification again) "cry out" that she "Stop!"
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!”(55)
At this point Macbeth enters, and Lady Macbeth repeats the predictions listed in his letter to her; she speaks of her joy. She will now begin to poison his mind so that he will not balk at what must be done, not only so he can be King, but that she can become Queen.