There’s good reason to discuss hobbits again this spring: On Friday, a biopic about the life of J. R. R. Tolkien opens in theaters nationwide, just as an exhibition of the author’s art, manuscripts, and maps concludes at the Morgan Library and Museum in New York City. The mumbling, mild-mannered Oxford professor who brought imaginary realms to life remains one of the most popular writers in the world more than 60 years after the publication of The Lord of the Rings. And if six Hollywood blockbusters weren’t enough, Amazon Prime is now producing a new series based on less explored parts of the Middle-earth mythology.

Such runaway success was never guaranteed for Tolkien. A close look at his life reveals that he faced fierce criticism and had his own doubts about his writing career. Tolkien was perhaps never so unsure of the future than in January 1945, when, with World War II winding down and The Lord of the Rings still nearly 10 years away from being released, he published a semiautobiographical short story titled “Leaf by Niggle” in The Dublin Review. The story provides a window into Tolkien’s creative process and his hope that fantasy stories, often considered mere children’s fare, would gain a genuine foothold in literature and transport readers to new realms.

In the story, Niggle is a painter, although “not a very successful one”—the type “who can paint leaves better than trees,” Tolkien writes. For some time, Niggle has been working on a painting of a great tree and its surroundings, but he can never seem to finish it, as he faces one minor setback after another. Eventually, Niggle is whisked away on a mysterious journey by train. He arrives at a workhouse, where his life is scrutinized by two disembodied voices. The voices send him to the countryside, where Niggle encounters his painting again, except that now he’s living inside it: The tree and the mountains he painted are real.

“Leaf by Niggle” is one of the only short stories Tolkien ever composed. Although he once wrote, “I cordially dislike allegory in all its manifestations,” this tale is indeed an allegory and not always the subtlest one: Niggle’s journey takes him through the stages of death. The workhouse where Niggle is evaluated is purgatory, and the countryside where he ends up is heaven. Although some of the story’s themes may be heavy-handed, the prose in “Leaf by Niggle” has an ethereal quality that evokes the transcendent. Its core ideas are honest and soul-searching. Aside from The Lord of the Rings and The Hobbit, it might be Tolkien’s finest work.

The autobiographical aspects of “Leaf by Niggle” stand out in particular. The story reflects Tolkien’s love of nature; in a preface to one reprinting, the author wrote that he was inspired by a “great-limbed poplar tree” he saw in real life that “was suddenly lopped and mutilated by its owner.” The tree’s only crime, Tolkien speculated, was being “large and alive.” In J. R. R. Tolkien: Author of the Century, the scholar Tom Shippey argues that the story’s plot is personal, with Niggle as a stand-in for Tolkien himself. Shippey notes that Tolkien was the perpetual “niggler” by the word’s dictionary definition—a perfectionist and procrastinator who dabbled in the minutiae of Middle-earth for years, creating languages and genealogies, but who had a hard time finishing stories. Those in the story who doubt Niggle can be read as Tolkien’s critics, including some of his Oxford colleagues, who found fantasy fiction to be childish and who couldn’t understand why a successful scholar would waste his time on it. But what makes “Leaf by Niggle” so useful for understanding Tolkien is how it illustrates his ambitious vision for what fantasy literature ought to be and do.

Tolkien believed that fantasy worlds need to seem real. In his essay “On Fairy Stories,” which has been reprinted together with “Leaf by Niggle” in Tree and Leaf, Tolkien explained that compelling fantasy depends on the author’s “subcreation” of a secondary world that has “an inner consistency of reality.” In attempting to achieve this verisimilitude, the author is, according to Tolkien, both a creator and a discoverer. He noted in a revealing 1955 letter to W. H. Auden that while writing The Lord of the Rings,

I met a lot of things on the way that astonished me ... I had never been to [the town of] Bree. [Seeing the character] Strider sitting in the corner at the inn was a shock, and I had no more idea who he was than had Frodo ... I was as mystified as Frodo at Gandalf’s failure to appear on September 22.

The idea of the writer or artist as a discoverer is underscored in “Leaf by Niggle.” The painter’s masterpiece is first described as having “begun with a leaf caught in the wind, and it became a tree ... Strange birds came and settled on the twigs and had to be attended to.” Niggle isn’t so much the maker of his painting as he is a wanderer in its realm. Tolkien felt that fantasy ought to be so immersive that even its creators feel as if they are exploring unknown lands that have always existed.

As lifelike as these fictional places might seem, Tolkien is conscious of the gulf between the real world and the invented one. Niggle’s art flourishes in his afterlife, but leaves little obvious mark back in his hometown; indeed, his canvas is used to patch his neighbor’s roof. Toward the end of the story, the reader learns that a single leaf is preserved in a museum (with the title Leaf: by Niggle), but the museum burns down, and “the leaf, and Niggle, were entirely forgotten in his old country.” Shippey’s autobiographical interpretation here is that Tolkien feared his own work would be forgotten. But this ending can also be read as a commentary on what Tolkien believed made good fantasy literature. Niggle’s painting becomes real elsewhere, regardless of what happens to the canvas.

Why travel to a location that is purposely disconnected from modern life? In other words, why read or write fantasy? Niggle’s neighbors, for example, see no value in his art; after Niggle departs for the afterlife, one townsperson wonders why he cared so much about the “digestive and genital organs of plants.” These comments echo those of skeptics who see fantasy as merely escapist. In his 1956 review, “Oo, Those Awful Orcs!,” the literary critic Edmund Wilson derided The Lord of the Rings as an “overgrown fairy story, a philological curiosity.” Even worse, the journalist and surrealist fiction writer Maurice Richardson declared that after reading The Two Towers, he could barely restrain himself from “slouching through the streets” with a signboard on which was written Adults of all ages! Unite against the infantilist invasion.

But Tolkien and his critics were talking past each other. The author believed that a well-realized fantasy world is just as important as mundane existence—if not more so. Tolkien also thought the genre should be escapist and offer renewal by emphasizing timeless themes such as nature and good and evil, as “Leaf by Niggle” demonstrates. At the close of the story, one of Niggle’s neighbors speaks wistfully about seeing a corner of Niggle’s painting: “It was damaged, but legible: a mountain-peak and a spray of leaves. I can’t get it out of my mind.” The reader then learns that the two voices who evaluated Niggle in the workhouse have begun to send many others to the country of his painting because of its great therapeutic value and restorative benefits. Fantasy, Tolkien suggests, is a way out that’s also a return to fundamentals: the tree and leaf, earth and stone. It revives those who are choking on the exhaust fumes of modernity.

Perhaps it is these qualities of fantastic realism and grounded escapism that make Tolkien’s works ever relevant. Middle-earth discards the trappings of modernity but still speaks to the human condition, transporting readers beyond everyday experience while remaining solid and true. If so many people nowadays choose to travel there, it’s because Tolkien explored it first and showed them the way. In “Leaf by Niggle,” as in his other, more famous writings, Tolkien’s prose becomes a portal to lands where there is always “a new road or a secret gate” and something very real and very valuable waiting to be discovered.