Bonta imagines the banjo's fifth string as a wanderer with a past. Before it found its place, it did odd jobs: holding up a weathervane, tensing a cat's body as it crouches, binding a broom. Each job involves tension and tightness, which is exactly what a string needs. Along the way it picked up skills too, like singing the wind's sorrows and toying with prey.
Then comes a playful twist. The banjo is "holding auditions," and the drifter lucky enough to wander by gets the part. The tuning peg fits the banjo's round, "bottomless" hole, as if the two were made for each other.
The tone is warm, humorous, and a little mythic, like a folk tale about how something came to be. The ending widens the view. The banjo "began to resemble itself," the way a forest fills its gaps with more trees. The string completes the instrument, and the poem suggests that belonging means becoming more fully what you already were.