Glamis thou art, and Cawdor; and shalt be
What thou art promised. Yet do I fear thy nature;
It is to 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. What thou wouldst highly
That wouldst thou holily; wouldst not play false,
And yet wouldst wrongly win. Thou’ld’st have, great Glamis,
That which cries “Thus thou must do,” if thou have it,
And that which rather thou dost fear to do,
Than wishes should be undone. Hie thee hither,
That I may pour my spirits in thine ear
And chastise with the valor of my tongue
All that impedes thee from the golden round,
Which fate and metaphysical aid doth seem
To have thee crowned withal.

After reading her husband’s letter bringing news of his new title and the Witches’ prophecy, Lady Macbeth delivers this soliloquy in Act 1, Scene 5. She’s overjoyed that her husband will become king, but worried that Macbeth will prove to be too weak to murder Duncan himself. She urges him to hurry home so she can persuade him to do so, since fate seems to want him to become king.

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 vistings 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 murd’ring ministers,
Whatever 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!’

Lady Macbeth gives this soliloquy in Act 1, scene 5, while waiting for King Duncan to arrive at her castle. She’s determined that Duncan must be murdered, and asks for help from the spirits to give her the courage she needs to kill him. The references she makes to being female reveal that she feels her natural womanhood may keep her from acting cruelly, so she demands that they be removed.

O, never
Shall sun that morrow see!
Your face, my thane, is as a book where men
May read strange matters. To beguile the time,
Look like the time. Bear welcome in your eye,
Your hand, your tongue. Look like th’ innocent flower,
But be the serpent under ‘t. He that’s coming
Must be provide for: and you shall put
This night’s great business into my dispatch,
Which shall to all our nights and days to come
Give solely sovereign sway and masterdom.

In these lines, in Act 1, scene 5, Lady Macbeth tells her husband to leave everything to her: she’ll set up Duncan’s murder that evening. In the meantime, she tells Macbeth, he should try to look as innocent as possible. The lines show Lady Macbeth pushing her husband to kill Duncan. We can’t know if Macbeth would have decided to murder his king if his wife hadn’t encouraged him so strongly.

But screw your courage to the sticking-place,
And we’ll not fail. When Duncan is asleep –
Whereto the rather shall his day’s hard journey
Soundly invite him – his two chamberlains
Will I with wine and wassail so convince
That memory, the warder of the brain,
Shall be a fume, and the receipt of reason
A limbeck only: when in swinish sleep
Their drenchèd natures lied as in a death,
What cannot you and I perform upon
The unguarded Duncan? What not put upon
His spongy officers, who shall bear the guilt
Of our great quell?

In Act 1, scene 7, Lady Macbeth dismisses her husband’s decision to let Duncan live, and promises him that if he can act with courage, their plan can’t fail. She tells Macbeth that once Duncan is asleep, she’ll get his servants so drunk that they pass out. Then she and Macbeth can kill Duncan and blame his servants for the killing. Lady Macbeth’s plan is good enough to convince Macbeth to change his mind and agree to kill Duncan.

I laid their daggers ready;
He could not miss ‘em. Had he not resembled
My father as he slept, I had done’t.

This short speech from Lady Macbeth in Act 2, scene 2 reveals two important facts: first, that Lady Macbeth has not helped kill Duncan after all, and second, that Duncan’s resemblance to her father prevented her from killing him. Lady Macbeth will have a complex reaction to the murder throughout the rest of the play, at times appearing to feel more genuine remorse than her husband for their actions. Her remorse will eventually lead to her suicide. These lines are an early suggestion that Lady Macbeth might not be as coldblooded as she claims to be.

Out, damned spot; out, I say. One, two, -- why, then ‘tis time to do’t. Hell is murky. Fie, my lord, fie, a soldier and afeard? What need we fear who knows it, when none can call our power to account? – Yet who would have thought the old man to have had so much blood in him.

In Act 5, scene 1, Lady Macbeth sleepwalks through Macbeth’s castle on the eve of his battle against Macduff and Malcolm. She is completely undone by guilt and has lost her mind. Similar to her husband’s guilt-induced hallucinations, Lady Macbeth has started seeing things that aren’t there – namely, blood on her hands, a physical manifestation of her guilt over her part in Duncan’s murder.