The center of Macbeth is the Gran scena del sonnambulismo, a scena without an aria—perhaps it could be called an anti-aria, indeed an anti-mad-scene, in the way that Mary Ann Smart has spoken of Azucena's music as an anti-mad-scene. As Verdi advised the first Lady, Marianna Barbieri-Nini, on 31 January 1847:

The Aristotelean words terror and pity show how far Verdi had gone in trying to force an Italian opera back into some pre-operatic, archaic model of tragedy. In the first three acts, terror predominates; but in the fourth act, terror is giving way to pity. The Scottish refugees are figures deserving pity; pity is the first word of Macbeth's wheedling fourth-act aria Pietà, rispetto, amore; and the sleepwalking scene is a psychiatric case history of a mind so blasted by terror, so burnt out, so evacuated, that the spectator's pity must be evoked to fill the empty space. Lacking “flowing, conventional melodies,” Lady must rely for expression on prettily arpeggiated accompaniment figures, filling the empty spaces between the ghosts of tunes.

One of the main elements of the sleepwalking scene, the double-dotted, gently stumbling figure in F minor over which the Doctor says, “O, how her eyes gape wide,” appeared early in the opera—in fact it was the second theme in the prelude to the first act. The prelude's first theme was that of the witches’ chorus at the beginning of the third act, Tre volte miagola la gatta (Thrice meowed the cat).