At the beginning of the scene, Macbeth has grave misgivings about killing the king. In his soliloquy, he enumerates to himself all the reasons why the killing should not take place. Then Lady Macbeth comes in and he tells her:
We will proceed no further in this business:
He hath honour'd me of late; and I have bought
Golden opinions from all sorts of people,
Which would be worn now in their newest gloss,
Not cast aside so soon.
Then she chastises him for going back on his word and for being a coward. She is strong and resolute, determined and single-minded. He is doubtful and scared... "If we should fail?" he says to her. She tells him that he should just listen to her and do what she says, and they will not fail.
Indeed one could say that, in the scene, Macbeth plays the faint-hearted female to Lady Macbeth's murderous male.
The scene also shows how the couple uses language. Macbeth begins the scene with a soliloquy, ornate with imagery. He lists more reasons not to kill Duncan than to kill him. But it is his "vaulting ambition" that will ultimately cause him to "jump the life to come." He's battling between his "intent" and "ambition," a kind of "supergo" and "id" battle to which Freud discussed.
Lady Macbeth has no such soliloquy in the scene. Her language is more blunt, business-like, plain. She asks many rhetorical questions--appealing to Macbeth's sense of manhood. It's highly emotional argument:
She's comparing Macbeth to a cat that doesn't want to get her feet wet when going after a fish. Very clever.
Of course, Lady Macbeth has already given up her "super ego" in the scenes before when she delivers her famous "unsex me here" soliloquy. In Scene 7, she is working from total inner child ("id"), and her emotional argument futher helps bring out Macbeth's inner child, thereby quieting his guilt in the pending murder. The line, "bring forth men-children only," then takes on an ironic twist.
The scene commences with Macbeth's soliloquy, 'If it were done when 'tis done....' which shows how he is divided between immoral ambition and moral scruples. Macbeth examines the pros and cons of Duncan's murder and admits that the ghastly 'deed' would be a breach of 'double trust': one of kinship and loyalty & the other of hospitality. Duncan being 'meek' and 'clear in his great office', his killing would force the killer into a state of moral isolation and inescapable retribution.
As Lady Macbeth enters to accuse her husband of having left the company of the king, Macbeth tells her--'We will proceed no further in this business', for he doesn't want to betray Duncan and also doesn't want to be fallen in public esteem. Lady Macbeth now assumes her chastising role, taunting and remonstrating her husband:
Was the hope drunk
Wherein you dress'd yourself? hath it slept since,
And wakes it now, to look so green and pale....
She calls Macbeth a coward which he is surely not, but her sarcasm that Macbeth is like 'the poor cat i' the adage' sounds very pinching. What follows betrays a strained violence of language:
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 pluck'd my nipple from his boneless gums,
And dash'd the brains out, had I so sworn as you
Have done to this.
The scene ends with Macbeth's counter-sarcasm at her so cruelly disposed wife--'Bring forth men-children only...' . Macbeth declares to comply with the murder-blueprint as worked out by Lady Macbeth.