“I like to call it ‘The Night the Poem Happened,’” Robert Wrigley says. Last week, Wrigley and fellow poet Ciara Shuttleworth sat in the Red Door, a low-lit and checkerboard-floored gastropub in Moscow, Idaho, kibitzing about an incident that happens maybe once in the life of a writer, if ever.

Wrigley’s name should be familiar — he’s the author of eight collections of poetry, including the new Beautiful Country, and a six-time Pushcart Prize winner. You’d be forgiven for not having heard of Shuttleworth, but if you read The New Yorker, you’ll be aware of her soon. “Sestina,” the work that sprang spontaneously into being on The Night the Poem Happened, will be published in the Nov. 29 issue.

An MFA student at the University of Idaho, Shuttleworth had signed up for Wrigley’s Prosody and Form course last spring because, she says, “I don’t know much about meter.” Before coming to UI three years ago, she considered herself an artist, not a poet.

One day, Wrigley arrived in class with a packet of poems in a form called the sestina, and the class set about looking them over.

The sestina is a complicated, archaic thing. Invented in France 800 years ago, the form is rigid, structured into six stanzas of six lines. The words that end the lines of the first stanza must be reused to end the lines of all ensuing stanzas. The final word of the final line of the previous stanza must also be the final word of the first line of the next. At the end, those endwords are grouped into a shorter stanza called an envoy.

Perhaps the best illustration of how complex a sestina can be is its popularity among such self-flagellators as Dante.

One poem in Wrigley’s packet, Lloyd Schwartz’ “Six Words,” caught Shuttleworth’s attention, not because it was brilliant, but because it seemed kinda … not.

The poem has only one word per line, and repeats them six times in different orders. The end result is, frankly, not much. “It’s a gimmick,” Wrigley says. “I almost didn’t put it in.” But the thing about gimmicks is that it makes people want to prove the fraud.

Shuttleworth says, “I thought, ‘I can do this.’”

Ten minutes later, she had. The class had moved on to a different poem when she interrupted: “Bob, I think I wrote one.”

Wrigley was unbelieving. “He said, ‘No, you didn’t. Read it.’”

Shuttleworth read it.

“He said, ‘Type that up. I want to see it on the page.’”

The rest of a traditional sestina isn’t as formalized as the endwords, and it’s across this breadth that poets often spread the bulk of their poem’s meaning.

Shuttleworth’s “Sestina” doesn’t have any other words, though, so the entire piece is subject to the rigor of the form. The same six words — “You,” “Me,” “Used,” “Well,” “Love,” “To” — are repeated seven times, in different orders. With so few words, controlling pace and emphasis is key. Things like commas and exclamation points and ellipses become meaningful.

“I think we all knew she’d done it,” Wrigley says, “but it was going to be the kind of thing where punctuation was very important.”

The poem that Shuttleworth transcribed, halting and elliptical, tells the story of a person who once felt loved, and who now feels betrayed — and also, in a sense, culpable — while being unsure what to do about those emotions. The whole thing, read aloud, is over in maybe 15 seconds.

Schwartz’ “Six Words,” reads like an exercise more than a fully realized poem. Shuttleworth’s reads like a swatch of dialogue from a breakup voicemail.

It’s difficult to imagine something so emotionally complex being written in 10 minutes, and impossible to describe in any detail (The New Yorker’s reprint policies prevent us from showing you here). But while Shuttleworth’s poem is as simple and short as a sestina can be, it’s also more emotionally complex and interpretable than most.

At a party soon after, Shuttleworth said she got a little drunk and lippy. “I told Bob, ‘I’m going to submit this to The New Yorker.’”

He replied, “I think you should.”

“I woke up the next morning and thought, ‘Shit, now I have to do it.’”

Two months later, she got an e-mail from Paul Muldoon, the New Yorker’s poetry editor.

Since that night last spring, Shuttleworth has tried to repeat “Sestina” many times since.

“Failed miserably.”

In a way, though, Shuttleworth said, the trying and failing is comforting. “People ask, ‘Why do you even try again?’ But I think we have to keep trying. It’s reassuring, because something that simple could seem like a scam. Computer generated or something.

“People will always look at a poem like that and go, ‘That’s easy, I could have done that,’”

Wrigley muses. “But the truth is, if you didn’t do it, then you couldn’t have.”

Novelist Jess Walter, in discussing the ease with which his most recent novel, The Financial Lives of the Poets, spilled from brain to page in a matter of months, once said, “I think you get one” — one piece of art that isn’t the result of a hell-march through bogs of blankness, self-doubt and drafting.

“Sestina” may be Ciara Shuttleworth’s one. If it is, she spent her free pass well. The New Yorker is the largest stage for poetry in the world, which, in Wrigley’s mind, makes it the most important. “Everybody reads The New Yorker,” he says. “It has a million subscribers and is read by probably three times that many.”

It’s a career milestone for any writer, and Shuttleworth has reached it while young.

In short, Wrigley says, “You got struck by lightning.”

“I did,” Shuttleworth replies, smiling.