Once upon a time, the Kennedy Center commissioned a musical fable for children called "A Soldier's Life" -- the 21st piece for young audiences created for its active but low-profile education program. The work, written by composer Stanley Silverman and librettist/lyricist Jeff Moss and directed by A.J. Antoon, will have its world premiere tonight sporting a more optimistic, less military title: "A Good Life."

But what's in a name, anyway? The key word in both titles is "life," but by any name, this show deals with the subject of death -- uncomfortable for any of us but especially awkward, one would think, for an audience of children.

"A Good Life" has some of the standard equipment of children's entertainment: a king, for example (actually, a czar, since it takes place in Russia); a beautiful princess; goblins and beggars and magic stuff.

Reports from rehearsals are that the tunes are great, and the script bubbles with life right up to the end. But the climactic episode is still a struggle with death, which the hero finally chooses to lose.

Everybody knows children should be introduced to the idea of death, as gently as possible, before they meet it in reality. Like many other productions for Imagination Celebration, the Kennedy Center's 2 1/2-week extravaganza for children, "A Good Life" is expected to have a long life in later school productions. The teachers' guide distributed to school groups that will pack most of the show's performances at the Kennedy Center includes a bibliography of 15 books that tackle the subject of death from one angle or another.

But how will it work in the musical comedy form? Check back after the audience reactions have been surveyed.

Death, tra-la-la. Here it comes, kids, ready or not.

Jeff Moss strongly believes that art for children should not be ghetto-ized into pleasant, superficial themes. "The only difference between art for children and for adults is vocabulary," he says. "Children will laugh or cry or be scared by the same things as adults, as long as they understand the words."

The story Stanley Silverman chose for this new musical is an adaptation of "A Soldier Faces Death," an old Russian folk tale distantly related to the one used by Stravinsky for his offbeat, jazzy classic in narrative-mime form, "A Soldier's Tale."

In this version, the soldier captures Death and puts him in a sack. This protects the world from a universal menace but also deprives people of their final refuge from incurable unhappiness, their release from unbearable pain. Noting that a world without death is not exactly a paradise for those who are old, weak or suffering, the soldier finally lets Death out of the sack and is the first to die.

"I'm ready," he tells Death in the final scene. Then: "Is that all there is to it? Am I dead? I feel lighter." And off he marches with Death into the unknown. The collaborators for this work could hardly have been more aptly chosen. Composer Silverman is one of the major innovators (and renaissance men) of musical theater today. He directed an award-winning production of Virgil Thomson's "The Mother of Us All," wrote the incidental music for the production of "Private Lives" that starred Elizabeth Taylor and Richard Burton, and has composed such unusual music-theater pieces as "Elephant Steps," "Dr. Selavy's Magic Theatre" and "The Columbine String Quartet Tonight!" None of this is kid stuff, but Silverman is undoubtedly an enfant terrible.

Lyricist Moss is probably best-known as a songwriter for "Sesame Street" and such movies as "The Muppets Take Manhattan" and the upcoming "Ewok II." He has a pocketful of Grammys for music but also is adept with words. The collaboration with Silverman included a high level of give-and-take, he says, "because Stanley is literate and I'm musical."

Both were excited by the special challenge of writing something very serious for children. The goal, Silverman says, was to find "a more direct language than grand opera, but still classy. I was told that they didn't want a 'kiddies show' but something with substance. The theme of death and, ultimately, the necessity of death was something worth dealing with -- it could be funny, entertaining, gripping and sad."

Musically, he says, he made "bolder choices than usual."

"The music is more direct and much clearer -- not as ambiguous as my music usually is," he says. But the style mixes classical and popular elements, even in a single song like "Goblins," which is sung by a czar with a haunted castle. "It starts like Mussorgsky and then turns into 'Ghostbusters,' " Silverman says. "He's having his 'Night on Bald Mountain' and he needs ghostbusters."

Silverman and Moss have been friends for years, but this is the first time they have collaborated. Both say they found the process exhilarating and highly productive. Moss would try out the songs with his own inexpert voice before they agreed on a final draft so they would know if amateurs could sing it. "I know what we mean," he would tell Silverman, "but until I can play it and sing it, nobody else will know what we mean."

Until rehearsals began, they had heard the music only in their own performances. "Neither of us is a great pianist," Silverman says. "I'm a guitar player. But Jeff would become Glenn Gould right before my eyes. Now, we have a pianist and it's kind of sad."