Poets have asked the heart to carry love, grief and courage for centuries. Dave Bonta's "Heartbeat" asks something humbler of it: to keep time. The poem never uses the word "beat". It comes at the pulse sideways, through metaphor, and what it finds is a small, funny, slightly uneasy meditation on how we treat the machinery that keeps us alive. The central idea seems to be that the heart works without pause, that we received it by luck, and that our thanks tend to be offhand and a little reluctant.
The opening metaphor is deliberately unglamorous. "One-note" is usually an insult, the label for a boring speaker or a predictable performer. Here it is simply accurate: the heart does have one sound, repeated. The word "instrument" also works two ways, because it can mean a musical instrument or a tool. That double meaning carries the poem from music, in the first stanza, to labour, in the last. The line break adds to this. The hyphenated "one-" is left dangling at the end of the line, and "note" waits on the next, so the single note is split in two, like a beat followed by its pause.
The second stanza is where the grammar turns slippery. "Which I have by chance" is plain enough: I happen to own this instrument, and I did nothing to earn it. But "supplying my applause" can attach to either party. Perhaps the heart supplies the applause, since a pulse is a rhythmic clapping that arrives without being asked for. Or perhaps I am the one supplying it, handing over my approval to a performer who never stops. The poem does not choose, and the doubt is productive. The heart is both performer and audience, and we cannot cleanly separate the thing that works from the person who is meant to appreciate it. The sound of the phrase helps too: "supplying" and "applause" share the clustered *p* and *l* sounds, which makes the line itself seem to clap.
The last stanza is the most interesting. "Calling work work" is a blunt, almost stubborn phrase, in the spirit of calling a spade a spade. Repeating the word also mimics a two-part heartbeat, so the line pulses as it states its meaning. The heart is not a symbol here but a labourer. Then comes "and other little grudgings", a surprising choice of word, since "grudging" is normally an adjective or a verb. Making it a plural noun turns it into a collection of small, reluctant concessions. The word "other" suggests that "calling work work" is itself one of these grudgings. Judging by the wording, admitting that the heart's effort counts as work is a minor, slightly unwilling act of credit. The applause of the previous stanza starts to look half-hearted too: a polite clap given without much thought. Whether the grudging belongs to the speaker, to the heart, or to both is left open, and the poem is arguably more truthful for it.
The form supports this modesty. There are three unrhymed couplets, with short lines of about four to seven syllables. They have no punctuation and no capital letters, and they end with no full stop. The whole poem runs as one loose sentence that simply stops, much as a pulse seems to carry on even when we aren't listening. The lines are too short to build a grand rhythm, and the poem has nothing like a lyrical swell or a dramatic climax. Its restraint is the one-note quality of its subject.
The poem matters for how much it does with so little. It takes one of the most worn-out symbols in poetry and strips it of sentiment, replacing romance with employment. Yet it is not cold. To call the heart an instrument is already to treat it as something that can be played, appreciated and perhaps thanked, and the clapping, however grudging, is a form of thanks. In about a dozen words it manages to be wry, grateful and a little guilty all at once, and it leaves the reader quietly aware of the steady sound they usually ignore.