How did J.R.R. Tolkien create The Lord of the Rings? The simple answer is that he wrote it. He sat down in a chair in 1937 and spent more than a dozen years working on what remains a masterwork of fantasy literature and a genius stroke of immersive worldbuilding.

The more complicated answer is that in addition to writing the story, he drew it. The many maps and sketches he made while drafting The Lord of the Rings informed his storytelling, allowing him to test narrative ideas and illustrate scenes he needed to capture in words. For Tolkien, the art of writing and the art of drawing were inextricably intertwined.

In the book The Art of The Lord of the Rings, we see how, and why.

The oversized tome by renowned Tolkien scholars Wayne Hammond and Christina Scull arrives next week to mark the 60th anniversary of the trilogy. It contains more than 180 sketches, diagrams, maps, inscriptions, and trial runs of his invented alphabets, all related to The Lord of the Rings and nearly 100 of which are just now being seen for the first time.

When you study Tolkien’s scribbles and sketches, a few things become clear. First, the narrative of Rings clearly consumed him. He wrote and drew, anytime, anywhere. Some drawings are dashed-off doodles inserted into margins of his manuscripts. Other are more meticulous. Even when he clearly labored over a drawing, such as the paintings and maps that graced The Hobbit or the small sample of handiwork seen in The Fellowship of the Ring—his maps, the script Frodo and Gandalf discover on the One Ring, an image of the Doors of Durin—Tolkien the artist was never satisfied, denigrating his works as "amateur" and "defective."

Tolkien didn't seem to care what he drew or painted on. His sketch of "Helm's Deep and the Hornburg," the fortress enclave of the Rohirrim people, is executed on a half-used page of an Oxford examination booklet. Drawn in perspective, the tableau nicely captures Tolkien's final description of the castle from The Two Towers: "At Helm's Gate, before the mouth of the Deep, there was a heel of rock thrust outward by the northern cliff. There upon its spur stood high walls of ancient stone, and within them was a lofty tower. ... A wall, too, the men of old had made from the Hornburg to the southern cliff, barring the entrance to the gorge..." One can imagine Tolkien pausing in the middle of grading a student’s paper, pondering how the castle wall and mountain valley might have appeared from a distance, both in his mind’s eye and the eyes of his characters.

The effort to map the geography of Middle-earth and capture its ambiance and hint of story, also can be seen in his trippy, colored pencil sketch "Moria West-Gate." Tolkien built a narrative into the drawing itself: The secret door, dwarfed by the cliff face, portrays the Fellowship's sense of awe upon seeing Moria, while the tiny waving tentacle of the Watcher in the Water portents the coming danger.

To be sure, Tolkien had to grapple with the fact that the Middle-earth of Lord of the Rings was a lot more complicated, and vaster, than the Bilbo-sized version in The Hobbit.

To be sure, Tolkien had to grapple with the fact the Middle-earth of Lord of the Rings was far more complicated, and expansive, than the Bilbo-sized realm of The Hobbit. The width and breadth of it probably felt overwhelming. Lothlórien and Gondor! Mount Doom and Edoras! Uruk-hai and Nazgul! So many homelands, races, and cultures to flesh out; buildings and environments to build; natural and man-made (and dwarf-, elf-, and hobbit-made) features to be pictured in his mind, carefully placed on the map, and turned into words. No wonder 17 years passed between the publication of The Hobbit and Rings.

In the three-part sketch of Saruman’s tower, "Orthanc (2), 3, (4)," we see Tolkien testing ideas. Here, he’s trying a gentler, rounded, tiered version of the tower, which matched an early draft of The Two Towers. Later, guided by his sketches, he described the structure more harshly: "A peak and isle of rock it was, black and gleaming hard: four mighty piers of many-sided stone were welded into one." In Tolkien’s process, his drawings and text informed and influenced each other.

Tolkien was an endless reviser. "Earliest map of the Shire" reveals his creative recycling. Pencil lines have been overlaid with blue and red ink. Dashed and dotted lines represent Frodo, Sam, and Pippin's route, or the boundaries of features like The Old Forest. In light pencil, upper right, "Elves" are added with a circle. Nomenclature changes; Tolkien gives "Puddifoot" a new name: "Maggot." The detailed maps printed in their finished form in Lord of the Rings help readers get their bearings. But as drafts, they must have helped Tolkien, too. "The 'First Map' of Middle-earth" was Tolkien’s master reference map; over the years, he glued new sheets on top of old ones as his story grew and changed in the telling.

The key lesson of The Art of The Lord of the Rings is this: We forget that it’s not only filmmakers who need to translate words into pictures.

Maps also helped Tolkien follow his characters across Middle-earth. This was a traffic control problem Tolkien exacerbated once he broke up the Fellowship at the end of The Fellowship, thereby unleashing diverging plotlines for at least three groups: Gimli/Legolas/Aragorn (later joined by Gandalf); Pippin/Merry (and Treebeard); and Frodo/Sam/Gollum (and Faramir). In two diagrams, "Map of Rohan, Gondor, and Mordor" and "Distances and dates in Mordor," we see Tolkien's supremely obsessive efforts to calculate the motions and locations of Frodo and Sam to the last millimeter (where 1 mm equals 5 miles). Topographic contour lines show mountains and the pitch of slopes. Why all the fuss? Tolkien wanted their journey to Mount Doom to sync with Aragorn's battle at the Black Gate. For fantasy to work, it must adhere to believable time-space principles. In a letter to his publisher’s proofreader, he revealed his writing process. He "started with a map, and made the story fit (generally with meticulous care for distances)," adding that its reverse, "to compose a map from a story" is "weary work."

If Tolkien's nerdy use of graph paper feels like a secret message to future Dungeons & Dragons players, then so does his "Plan of Shelob’s lair." Tolkien’s map of tunnels stocked with nasties—here, a spider named Shelob—would be right at home in any Dungeon Master's campaign notes. He even marks the place for a classic dungeon crawl feature: "trap."

His art also shows him having fun. Like a kid torching the edges of a fake treasure map, Tolkien drew facsimiles of documents, such as the Book of Mazarbul, as it supposedly appeared to the Fellowship in Moria, "slashed and stabbed and partly burned." These elaborate faux documents supported Tolkien's fanciful idea that he didn't write The Lord of the Rings—rather, he’d found ancient legends, and edited and translated them for our benefit. For a guy who wrote old-fashioned high fantasy, Tolkien was surprisingly post-modern in his literary conceits.

The key lesson of The Art of The Lord of the Rings is this: We forget that it’s not only filmmakers who need to translate words into pictures. For those who complained about Peter Jackson's adaptations of Tolkien's novels into indelible screen imagery, these drawings remind us that even novelists have strong ideas about the look and feel of their worlds. Tolkien's imagination spoke both image and word, probably the hybrid language the mind thinks with anyway. So hey, fiction writers: If you think worldbuilding is all about knocking out words on a laptop, Tolkien proves that the paintbrush and sketch pad can be mightier than the keyboard.

In a letter from 1937, Tolkien spoke of having "some 'pictures' in a drawer, but though they represent scenes from the mythology on the outskirts of which the Hobbit has his adventures, they do not really illustrate his story." Those pictures became ways to visualize parts of Middle-earth that he had not yet begun to write about. The world he built extended into his art. His art breathed life into the corners of that world he would never find the time to write about. At the same time, those drawings, maps, and doodles also helped readers immerse themselves in his never-before-seen invented realm, "a world," Tolkien’s friend C.S. Lewis once noted, "that seems to have been going on before we stumbled into it."