Around 2012, I began to hear from friends about a remarkable young poet, still an undergraduate at Yale. I never met Max Ritvo, but in the years that followed I felt that I came to know him: his friendly curiosity, his wit and preternatural lyric gifts, and, terribly, his illness. Given a diagnosis of Ewing’s sarcoma, a rare form of cancer, when he was sixteen, Ritvo died in 2016, at the age of twenty-five. His emergence as a writer was, in fact, a record of his imminent disappearance. He was making himself unforgettable, one vivid trace at a time.

In 2013, Ritvo began an M.F.A. program at Columbia University. Clips of his readings turned up on YouTube, and spread: friends described to me with animated precision poems that I had not yet seen. As they were published—in magazines, in a chapbook, “Aeons,” and finally, posthumously, in his début volume, “Four Reincarnations”—they almost seemed late to the party. And yet they still came as a shock. Writing in Poetry, Helen Vendler compared their effects to strobe lighting: Ritvo’s talent illuminated his material starkly and brightly, “flash after flash.”

A poet whose début appears after his death inhabits time in a loopy way. We now have two new volumes of Ritvo’s work, fresh pranks played at time’s expense, prepared by two of his beloved friends and teachers. “The Final Voicemails” (Milkweed), edited by Louise Glück, includes a selection of astonishing new poems and a version of Ritvo’s undergraduate thesis, “Mammals.” And Sarah Ruhl, a playwright and Pulitzer Prize nominee, has compiled “Letters from Max: A Book of Friendship” (Milkweed), a strange and beautiful volume made up of Ruhl’s correspondence with Ritvo, including poems they inspired in each other. Together, these books suggest that Ritvo’s legacy, like Emily Dickinson’s, will resemble not a solemn monument but a vibrant workshop, left open for readers to explore. Ritvo’s work and life have been preserved in a small archive of primary documents: finished poems alongside earlier variants, letters and e-mails, interviews and obituaries. You can assemble your own Ritvo from this ample record of his mind. His œuvre is not large, but the paths a reader can take through it branch endlessly. His poetry is now in others’ hands, as he must have both hoped and feared it would be.

“Letters from Max” suggests that Ritvo’s imagination flourished in camaraderie. He wrote almost all of his poems with the expectation that talented peers and teachers would read them. “He didn’t want to chirp his epic songs into an unsinging receptacle,” Ruhl writes. “He wanted a poem to answer a poem. He wanted his writing to beget more writing.” Like love, it was “relational,” a mirror of a mirror: “the person we love is trying to love us.” His poems sometimes emerge from real conversations, which they, in turn, convert into dream logic and symbol. “A big chunk of our conversing today ended up in a very strange poem-thing,” Ritvo writes in an e-mail to Ruhl. The “poem-thing” he includes, “Listening, Speaking and Breathing,” appears, slightly but brilliantly revised, in “The Final Voicemails.” Readers can compare the two versions of its final lines. In the e-mailed draft, Ritvo seems to address Ruhl directly:

If I am still an object,
Then we’ll know that, won’t we?

I hope then, you’ll talk to me,
And I promise I’ll make sense of you.

Ruhl writes back that the poem is “gorgeous and sublime,” and answers its haunting query:

My other input is that the answer to the question posed in your poem is always yes—

the eternal yes that poets sing about,

the yes of the poet’s immortality.

When Ritvo revised his original lines, he added one clause (emphasis mine): “If after the poem I am still an object.” What was latent in the original becomes explicit in the revision. Ruhl, by answering something Ritvo didn’t exactly ask, forces him to reframe the question, broadcasting it to posterity. It’s an old trick poets play: if we’re reading these lines “after the poem,” Ritvo gets his immortality. The poems provide their own proof.

The friendship between the two writers was, from the start, a self-conscious literary dialogue. In 2012, soon after they met, Ritvo saw Ruhl’s play “Dear Elizabeth,” based on the letters of Elizabeth Bishop and Robert Lowell. Afterward, he told her that he felt as though it had been “written for him.” According to Ruhl, in their correspondence Ritvo “played the role of Lowell in his expansiveness,” while she “had the role of Bishop—looking for reduction, distillation, hoping to glimpse something sideways, indirectly.” Lowell and Bishop did a lot of role-playing, too, bending their self-presentations to please each other. And yet the correspondence we encounter in this book lacks the wickedness of gossip, the mean fun of auditing human pettiness and absurdity—so often a natural basis for intimacy. The total absence of this register between dear friends makes you feel how fragile life must have seemed to them. Most everything here is tender; sometimes it is willfully so.

Ritvo will often pick up a friendly mutual motif—their shared love of soup, in one instance—and put it to shocking metaphorical use. Describing his radiation treatments, he writes:

But the most heartbreakingly beautiful just-for-you thing is the sound the machine makes when the beam is emitted. Sarah, it sounds exactly like a tiny man with a tremor is opening up a can of soup inside the gun. There’s an almost liquid echo once he opens the soup as the beam goes in. I swear I almost cried the first time I heard the little soup opening. It was the least likely place in the world to find soup, and to find someone tending to soup, and there it all was.

Ritvo’s imagination flares up at that awful noise, conjuring the image of a man not merely serving soup but “tending” to it. His near-tears are not for his own predicament; they have been displaced onto his creation. Turning potentially indulgent self-pity into expansive compassion is a move familiar to readers of his poems. Ritvo didn’t invent this kind of deflected intensity, but he employs it in extremis, describing torments most of us can hardly fathom.