Dramatically and poetically, this scene precisely mirrors Act I, Scene 5. Then, Duncan's death was being plotted; now, the death is Banquo's (although Lady Macbeth is initially unaware of this). In the earlier murder, Lady Macbeth was most in command; in this murder, Macbeth is. Where formerly Macbeth was the one who needed convincing, now the weaker role passes to his wife. Macbeth's line "make our faces vizards (visors) to our hearts" recalls Lady Macbeth's earlier words "[t]o beguile the time, look like the time." Similarly, Macbeth's injunction to the spirits of darkness "Come, seeling night . . . " is an echo of the speech of Lady Macbeth's beginning "Come, thick night . . . ."
Despite Macbeth's personal bravado, neither he nor his wife seems entirely at ease. Lady Macbeth talks of her "doubtful joy" and Macbeth of his "restless ecstasy." In the world that the Macbeths have created for themselves, total peace no longer exists, and what has been achieved is only a half-measure. Even the dead King Duncan is able to achieve more totally what Macbeth never can: a respite from "life's fitful fever."
While Lady Macbeth appears to be looking back at the previous murder, Macbeth looks forward, anticipating the next murder, of which Lady Macbeth is not yet fully aware. That distinction between their two states of knowledge allows Shakespeare to play once more on the power relationship between husband and wife. Here, then is yet another reversal of character, and it is shown in two major ways: first, by Lady Macbeth's innocent-sounding questions and, second, by Macbeth's adoption of animal imagery. In Act I, Scene 5, Lady Macbeth was the one who spoke of "the raven" and "the serpent." Now Macbeth takes on the same language of horror, imagining his mind to be "full of scorpions," and speaking of the "bat" and the "shard-born (dung-bred) beetle."
