n an introduction to the score for his "Darkbloom: Overture for an Imagined Opera," which will have its premiere with the Boston Symphony Orchestra tonight, John Harbison calls the piece the remnant of a misguided project, an "unproduceable" opera based on a "famous and infamous" American novel.

What made it unproduceable, at least in part, was the Roman Catholic Church's sexual abuse scandal involving priests and minors, Mr. Harbison said in an interview this week. The novel was Vladimir Nabokov's "Lolita," a work about a man's passion for an adolescent girl.

"I suppose the subject matter never has been more socially unacceptable than it is now in the United States," Mr. Harbison said. "Obviously I began to think more about that."

Mr. Harbison said he wrote a scenario of an opera based on "Lolita" in 1999 and sketched out musical sections. Then, in early 2002, the church's sexual abuse scandal broke in Boston. Mr. Harbison, one of the nation's most celebrated and successful contemporary composers, happens to live in Cambridge, Mass.

He said he was widely counseled to drop the project, and did so, demonstrating the novel's continued power to stir debate.

"It's just difficult to detach it, particularly living in Boston, from one of the central news events of recent times," Mr. Harbison said.

Mr. Harbison valued the material he had produced, however, enough to recast it as a seven-minute overture when James Levine commissioned the piece for his first season as music director of the Boston Symphony. The work will be performed on the orchestra's program at Carnegie Hall on Monday.

The title comes from Vivian Darkbloom, a minor character in the novel and an anagram of the novelist's name. Mr. Harbison, in the introduction, said he had no regrets about abandoning the project.

He wrote, "Nor do I have any difficulty in understanding why certain material, even in the realm of opera (which has harbored fratricide, patricide, incest and rape), is untenable on our present-day stage regardless of its artistic merit or its rendering."

Cryptically, Mr. Harbison never mentions the title of the novel in his introduction or explains why the projected opera was unproduceable. In the interview, he said it was unnecessary given the controversy that had greeted the book and its offspring in the past. He said being vague would avoid offending anyone who would be disturbed by the issue.

Mr. Harbison emphasized, however, that he had pulled the plug on an operatic "Lolita" at least as much because of difficulties in setting the material.

"I deeply believe, in some rather interestingly perverse way, it is a comic story," he said. But it is the kind of comedy that is difficult to put on the stage, he said.

In a previous joint interview with Mr. Harbison and Mr. Levine, the conductor said: "The reason the book is a masterpiece is because the subject is repellant and the treatment is this ironic humor. In an opera, you can't do that."

He also said, "You don't have the same relation to the text of an opera."

Moreover, writing operatic comedies is extremely difficult, Mr. Harbison said, pointing out how few truly great comic operas exist. Next to their large tragic and romantic output, Verdi's "Falstaff" and Puccini's "Gianni Schicchi" are exceptions, he said.

Mozart, he added, was a gifted comedic writer. "Mozart comedies are really about sex and the force of eros in the world, which is a comic subject, but very serious and very immediate," Mr. Harbison said. "The reason that Mozart was able to do it was because it was his subject, above all."

Mr. Harbison said the overture contains musical material from several scenes from the book, including Lolita's tennis game with a friend; the sound of children's laughter heard by the narrator, Humbert Humbert, at the end; and Humbert's first glimpse of Lolita: "A blue sea-wave swelled under my heart and, from a mat in a pool of sun, half-naked, kneeling, turning about on her knees, there was my Riviera love peering at me over dark glasses."