Even monsters have mothers. That message is at the heart of John Gardner’s 1971 novel “Grendel,” a reshaping of the 10th-century Danish tale, “Beowulf.” While that epic is named for the warrior-hero who slays a murderous beast, Mr. Gardner’s story is told from the point of view of the beast, Grendel. And in his novel, the repulsive, Dane-eating monster appears more recognizably human than any of the stiff-necked, blinkered men who seek his demise.

It’s a fascinating perspective. But bringing this soulful monster to the opera stage for “Grendel: Transcendence of the Great Big Bad,” which opens at Lincoln Center Festival tomorrow, was no easy matter.The production — with music by Elliot Goldenthal and a libretto by Julie Taymor and poet J.D. McClatchy — took 20 years and $2.8 million to reach completion.

One of the challenges inherent in the project was how to translate an introspective novel into opera, a medium that thrives on spectacle and dramatic action. Mr. Gardner’s title character yearns, suffers, rages, pines for companionship, misses his mother, and questions the meaning of his existence. The narrative is filled with philosophical ruminations on life and death. It’s not exactly “Carmen.”

Ms. Taymor and Mr. Goldenthal, who are partners in life and work, had their sights set on this project two decades ago. And they seem ideally suited for it. Celebrated for her staging of “The Lion King,” Ms. Taymor also dazzled Metropolitan Opera audiences in 2004 with her production of Mozart’s “The Magic Flute.” Who better to take on a mythical medieval encounter trapped in an existentialist whirlpool? (Of course, hiring visionaries carries risks: A glitch in the computer system that controls the opera’s elaborate scenery caused a costly postponement of the Los Angeles premiere.) Mr. Goldenthal, a prolific film composer, won an Academy Award for his soundtrack to the movie “Frida,” directed by Ms. Taymor. The two have collaborated on other projects, including “Juan Darien,” a carnival mass for masks and puppets.

Despite this considerable experience, their initial draft of “Grendel” was, from all accounts, overlong and too ambitious. Many of the elaborate stage directions written by Ms. Taymor had to be dropped. The text had grown out of control. And so they invited Mr. McClatchy to join in the effort. No stranger to opera, Mr. McClatchy’s recent librettos also include those for Ned Rorem’s “Our Town,” Lorin Maazel’s “1984,” and Lowell Liebermann’s “Miss Lonelyhearts.”

“As it stood, the opera would have had a length of nine hours,” Mr. McClatchy said. “Their sequence was fine. But they had taken big chunks of the Gardner prose, and it was kind of flat, dramatically.”

Mr. McClatchy sees libretto writing as very different than that of other forms of theater. “I think poetry was a good preparation, because it is as much an art of leaving things out as of putting things in,” he explained. “That search for the perfect word or the balanced line comes in handy when you are working in a form that demands a great deal of concision, and where you have to turn over the emotional argument to the music.”

Though the subject for an opera usually comes from the composer, the librettist does his initial work in weeks rather than years.The words have to suit not only the dramatic narrative, but also the composer’s style. Mr. Mc-Clatchy said that he thought less in terms of character and more in voice type when he wrote this libretto, picturing the sound of a soloist who may then combine with others. And, as always, he tried to match the texture of the language with what he knew of the composer’s sound.

Composer Elliot Goldenthal faced challenges of his own in supplying the musical foundation of “Grendel.” There was, for example, the knotty problem of maintaining interest during the first half of the opera, when the action is minimal, and the audience is learning who Grendel is. “Of course, ‘Tristan and Isolde’ has very little action, and Wagner sustained it for four hours,” Mr. Goldenthal said by way of comparison.

Yet, an aspect of the compositional craft underlying “Grendel” involved coming up with devices to keep the dramatic tension from collapsing. One technique he used was to have several singers express aspects of a single character. “Grendel talks to himself,” Mr. Goldenthal said. “So I broke the dialogue up and shared it among the beast’s shadows, or alter egos. That allows him to have duets, trios, even quartets.”

It presents a dual advantage of preventing Grendel’s voice from becoming tiresome to listeners, and also of giving the main character some relief. The Dragon — which in Mr. Gardner’s novel is male — is here a mezzo-soprano singing in the very lowest part of her range. Here again, the composer says, multiple voices have been put to use: “She has her Dragonettes, who are high sopranos, creating, in effect, a super-human woman’s range for the creature.”

The sheer size and scope of this production was another element with which Mr.Goldenthal had to contend: It was a world away from writing for film, where, he says,”sometimes five seconds of music makes all the difference.” Here, the scale and the resulting need for architectural planning is monumental.The final work,intricate in its details but shaped to match the rhythm of a long evening, requires all the resources of a large orchestra, singers, dancers, and puppets.

As Mr. Gardner put it in his celebrated treatise on the art of writing, “On Moral Fiction,” art is “a game played against chaos and death, against entropy. It is a serious game, for those who have the wit to take it seriously, because our side must lose….” In the end, Grendel, the sensitive monster who dies a poet, is indeed the loser. But thanks to Mr. Goldenthal, Ms. Taymor, and Mr. McClatchy, the battle has been joined again.

July 11, 13, 15, and 16 (New York State Theater, 212-721-6500).