When I think of the evolution of secondary world fantasy through the ’70s, ’80s, and ’90s, familiar names come to mind: Terry Brooks. Katherine Kurtz. Stephen R. Donaldson. Raymond E. Feist. Robin Hobb. Anne McCaffrey. George R.R. Martin. J.K. Rowling. Each of these authors impacted fantasy in ways that still ripple through the genre, influencing new authors who in turn reshape the genre and set imaginations whirring anew. Right smack in the middle of that group is Tad Williams, author of Memory, Sorrow and Thorn—an mid-’80s epic fantasy trilogy that breaks the mold created by J.R.R. Tolkien’s classic Lord of the Rings.

Williams’ trilogy (The Dragonbone Chair, Stone of Farewell, To Green Angel Tower) is quietly one of the most influential fantasies of the past 30 years, and is, in large part, responsible for the resurgence in the mainstream popularity of fantasy via HBO’s Game of Thrones, the television adaptation of Martin’s hugely popular A Song of Ice and Fire novels—after all, Martin credits Williams’ books as a primary inspiration.

On the surface, Memory, Sorrow and Thorn sounds like a paint-by-numbers secondary world fantasy: there’s an ancient evil threatening the medieval-flavored land of Osten Ard, a boy with a mysterious past, a scrappy princess, an evil prince, a dying king, and more magic swords, dragons, elves and dwarfs thank you can shake a wand at (even if they’re referred to by different names.) It never eschews these tropes—though at the time they were less tiresome, as fantasy-readers reveled in the post-Brooks/Donaldson revitalization of secondary world fantasy. Instead, Williams’ trilogy feels like a surgically-precise dissection of those tropes.

Betsy Wollheim, Williams’ longtime editor, remembers his first ambitions for Memory, Sorrow and Thorn (then called “The Sons of Prester John”) in her introduction to the 2016 edition of The Dragonbone Chair:

“Well, there’s this other project, but I’m not experienced enough to write it.” I was intrigued. I asked him to tell me more. We talked, and the longer we talked the more excited I became. Tad said this big project was his ode to King Arthur, to Lord of the Rings, to Mervyn Peake’s Gormenghast, and to “all the great books that made me who I am.” He went on to say that it was about the sons of Prester John, and that it was, in some ways, about what happens when a great king dies. He also mentioned that he didn’t want to write a Tolkien pastiche. He wanted this work to be more multidimensional, more modern—Tolkien was only one of his many inspirations. He said he had been thinking about this work for years. I knew instinctively that this had to be Tad’s next project, whether he was ready to write it or not. —Betsy Wolheim, “How Tad Came to Write The Dragonbone Chair”

David Barnett continued the conversation about the trilogy’s origins in The Guardian: “Williams didn’t just subvert the tropes of fantasy fiction,” Barnett said, “he asked readers to also question them, particularly the idea of a golden age, that ‘the past was brighter, more elegiac, more beautiful, that it’s a transitory state in a fallen world’. He pauses, almost as if to consider this possibility. ‘But what if the idea of the golden age is false? What if it had its own secrets?’”

The way Williams manages to couch these subversions—these larger questions about the nature of myth and story—among comfortable tropes is remarkable. The Sithi are deliberately Tolkien-esque, and the books bear the influence of everything from Dungeons & Dragons, to Celtic myth, and the tale of King Arthur. The longer you spend in his world, the more you realize he isn’t copying the foundations for western epic fantasy, but breaking them down, tinkering with them, and reassembling to fit his own vision of what Tolkien introduced to the masses. If Tolkien created created modern secondary world fantasy, Williams reinvented it—opening the doors for so writers to follow him through it—like George R.R. Martin.

“Tad’s fantasy series […] was one of the things that inspired me to write my own seven-book trilogy,” Martin said at a 2011 book signing. “I read Tad and was impressed by him, but the imitators that followed—well, fantasy got a bad rep for being very formulaic and ritual. And I read The Dragonbone Chair and said, ‘My god, they can do something with this form,’ and it’s Tad doing it. It’s one of my favorite fantasy series.”

To say Williams met his vision for the trilogy is a vast understatement. Neither he nor Wollheim knew it at the time (though she might have suspected), but Williams was about to begin working on an opus that would change the direction of fantasy for decades to come.

It’s always important to consider context while reading an older book. While Memory, Sorrow and Thorn can feel formulaic to a first-time reader in 2017, it was remarkable and formative when first published. In hindsight, it is fascinating to recognize how Williams bridged the gap between the Tolkienesque fantasy of Terry Brooks and Martin’s more complex modern epics.

Right off the bat, though, it’s impossible to discuss without addressing the elephant in the room: The Dragonbone Chair is long and achingly slow, especially the first 150 to 200 pages. So much so that many readers bounce off the book early, and miss out on one of fantasy’s most remarkable stories. “It’s certainly the thing that the largest percentage of readers have had a problem with,” Williams admitted during an AMA on r/Books in early 2017,” although other readers love it. I intended, as I think Tolkien did, to start slowly in order to familiarize readers with the place and way of life that was going to be put in danger.”

When we’re first introduced to the protagonist, Simon, he’s a young, put-upon kitchen scullion at the Hayholt, the seat of the High King Prester John—literally the definition of a classic trope. He’s called “mooncalf” by the other castle servants, his mind constantly lost in his dreams of adventure, danger, and derring-do. Hardly a hero. Williams builds up the Hayholt and its myriad inhabitants—from aged King John, to the whimsical scholar Morgenes, to vicious prince Elias, to harsh taskmistress Rachel the Dragon—one meticulously placed piece at a time.

In parallel to Simon’s life at the castle, this opening section is slow and uneventful—but, like Tolkien’s efforts in the Shire during the first half of The Fellowship of the Ring, Williams is purposefully creating a sense of normalcy to life in the Hayholt, giving readers an idea of what’s at stake, and encouraging them to care about the people Simon knows and loves. During rereads, I absolutely adore this part of the trilogy—its homey and comfortable. The way Williams breathes slow life into his creation is remarkable. You truly do care about Simon’s world, and when it’s turned upside down, you are as shocked as he is. On first read, however, it’s a tough slog.

It may surprise you to hear that I was once one of the unfortunate victims of this opening salvo. Several times, in fact. The first time I picked up The Dragonbone Chair, I was 17 or so. I’d read Tolkien and Brooks, Salvatore, some Fiest, and other high-action secondary world/adventure fantasy. I desperately wanted to like Williams’ work, but I bounced off of the Hayholt like a bag of mud flung from a trebuchet. A few months later, I tried again, finished the first book, started Stone of Farewell, and bounced again. Then again, a time after that. No matter how much I wanted to like it, it was the wrong book at the wrong time. Fast-forward several years, after I’d discovered Robin Hobb and George R.R. Martin, and loved the first volume in Williams’ second fantasy series, Shadowmarch. I came back to Memory, Sorrow and Thorn with a new appreciation for layered epics, and I devoured it. Despite having read The Dragonbone Chair three or four times by that point, I couldn’t put it down.

What at first seemed slow or meandering suddenly revealed itself as rich and intricate. Every step of Simon’s journey, from his early days climbing Green Angel Tower and evading Rachel the Dragon, to his first encounters with the mysterious Sithi, to his confrontation with a dragon, is significant. There are many words, but they are never wasted—instead, they are each a drop in a vast, ancient ocean. Few series—even those many times longer than Memory, Sorrow and Thorn, like Steven Erikson’s Malazan or Robert Jordan’s Wheel of Time—have left me feeling quite so startled by a world that seems to truly exist outside the pages of its books.

It’s marvelous to watch Williams add layer after layer to his myths, subverting what you think you know about the world as he reveals the tender vulnerability of the Sithi, the vengeance-fueled rage of the Norns. Many of the trilogy’s myths, histories, and religions are echoes from our own world—clear parallels to, among others, King Arthur, Baba Yaga, and Amaterasu appear at various points. This crossover, most prevalent during the first half of The Dragonbone Chair, when Williams is clearly still feeling his way through the world, grounds the world of Osten Ard, and gives it an ancient gravitas other created worlds have trouble replicating. It feels ancient, lived in.

I believe this is in part because Williams was discovering the world—its myths, its boundaries, its characters—at the same pace as the reader. Consider this, from his introduction to the 2004 edition of The Dragonbone Chair:

“As I wrote, I discovered things that hadn’t been in my outline, found the history of Osten Ard growing thicker and more complex almost by itself, and ran across serendipitous little bits that seemed to explain other ideas with which I had been toying. I invented characters like the monk Cadrach or the wise woman Geloë who were meant to be little more than interesting walk-ons, but who refused to leave the stage after their small parts had been enacted, and who later proved to have connections all through the story as well as crucial destinies in the completion of the tale. By the end of that book, I felt as though I had a grasp on not just what the story was about, but about what kind of story it really was: that it was about learning to be in the world, not just growing up in the ordinary sense, but learning how to become a thinking, feeling individual, a moral and ethical adult, and how to fight for what is important without letting the fight itself turn you into something else.”

Aside from the gorgeous worldbuilding, which draws plenty on various real world religions and cultures—the British Isles, Vikings, Christianity, Inuit, and the nomads of the Mongolian-Manchurian grasslands—Memory, Sorrow and Thorn succeeds wildly on the back of its changing and evolving characters. Throughout the trilogy, Simon, Miriamele, Binanik, and the rest of the cast—good, bad, or somewhere in-between—face tremendous challenges, altering their courses in life, their places in the world, or their understandings of human nature. People change—truly and utterly—from the first page to the last. This makes rereads even more satisfying, as you marvel at Simon’s early oafishness, Prince Josua’s brooding, or Tiamak’s tentativeness. In many ways, they are totally different. War, and life, happens.

Even on a second or third read, Memory, Sorrow, and Thorn doesn’t reveal itself until you start considering the work as a whole. It’s easy to dismiss it at any point along the way, especially before reaching the conclusion of the first volume.There’s a level of commitment required, but also a tremendous sense of accomplishment when you reach its conclusion. It’s certainly not light reading (figuratively or metaphorically), but it rewards perseverance. Watching its disparate threads pull together to form a stunning tapestry amid one of the most explosive endings in all of fantasy offers one of the finest experiences available to a genre reader.

By influencing George R.R. Martin to write A Game of Thrones, Williams set the world on a collision course with modern epic fantasy. Its recent upsurge in popularity would not have happened if that young writer had not sat down with his editor and pitched a crazy idea about a book he didn’t think he was ready to write. But the series is much more than just an inspiration for a blockbuster epic—it’s a beautiful transition between post-Tolkien idealism and the epic fantasy of today.

On June 27, 2017, Williams returns to Osten Ard with The Witchwood Crown, the first volume in a new trilogy more than two decades in the making—The Last King of Osten Ard. Some 30 years after he first introduced readers to his rich fantasy world, Williams has a lot to live up to. Like his protagonists, Simon and Miriamele, readers have changed in the interim—grown up, become adults—and The Witchwood Crown is an exploration of how people and cultures adapt in the wake of world-shattering events. As thoughtful and inquisitive as anything Williams has written, it is a promising beginning to a new fantasy classic. But that’s a story for another time.

The complete Memory, Sorrow and Thorn trilogy is available now. The Witchwood Crown is available June 27 is a signed edition from Barnes & Noble.