Sonnet 128 is one of the few sonnets that create a physical scene, although that scene involves only the poet standing beside "that blessed wood" — probably a harpsichord, a stringed instrument resembling a grand piano — that the Dark Lady is playing. The sonnet is comparable to Sonnet 8 in that both concern music, but Sonnet 128 speaks of "my music" while Sonnet 8 speaks of "Music to hear," a subtle distinction in feeling, with Sonnet 128 the more sensual of the two.
Jealous of his mistress' touching the instrument rather than him, the poet fantasizes about kissing the woman in the same tender, controlling manner that she uses when playing. What makes the sonnet so physically sensual despite the poet's never once touching the woman is not only his description of her playing technique but his personification of the instrument's response to the woman's touch. He envies "those jacks that nimble leap / To kiss the tender inward of [the woman's] hand" and resents "those dancing chips, / O'er whom [the woman's] fingers walk with gentle gait"; in his mind, his "poor lips" should be kissing her, not she the "dead wood."
In the concluding couplet, the poet continues to personify the wooden instrument's levers, calling them "saucy jacks so happy" because the woman physically touches them. The only consolation the poet has is his fantasy of kissing his mistress, which is an empty comfort given that the poet craves the sensuous touch the Dark Lady uses as she plays the musical instrument.