At best "Nightingale," the new opera for children by award-winning Broadway composer Charles Strouse, is a serious treatment of love, beauty and death--and particularly of the need for freedom as a basis for love and beauty. Elsewhere, it is a collage of satirical observations on power, bureaucracy and vanity, foolish fads and fashions, and the antics of artificial people when they encounter the forces of nature.

These elements coexist somewhat uneasily in a rather crazy, mixed-up but skillfully crafted show. Even in its present condition, as presented at the Wolf Trap Barns, it deserves to be seen--although it still needs some work. It is based on the story "The Emperor and the Nightingale" by Hans Christian Andersen, but parts of it call to mind his other story, "The Emperor's New Clothes."

At the show's climactic point, just before the happy ending, there is a drastic shift of gears; an evening's entertainment that has been devoted mostly to satire and slapstick becomes deeply serious. The Chinese Emperor (very well portrayed by John Schuck from the original cast of "Annie") has caught a glimpse of beauty in the song of the captive nightingale, suffers when the bird flies back to the forest, and suddenly faces a summons from Death--a hooded figure clad in white, which is the Chinese color of mourning.

As the Emperor's resistance slowly weakens, the nightingale returns, strikes up her song and begins a symbolic combat with Death, beautifully choreographed in a style that uses some of the conventions of Peking Opera. It is the best moment in the show, though many others are very good: a brilliantly comic aria and chorus featuring a mechanical nightingale who owes something (but not much) to Olympia from "Tales of Hoffmann"; several charming arias by a chambermaid who turns out to be the heroine; a funny chorus showing the discomfort of courtiers on a nightingale-hunt away from their natural (that is, unnatural) environment; the preening and antics of the Emperor's two pet peacocks, who are terribly jealous of "that little gray bird"; a very funny duet by two court physicians who disagree on all points of diagnosis and treatment; and above all the character and music of the nightingale itself.

All of this is presented in a very polished performance by a cast that includes a few adults but is mostly made up of teen-agers from the First All Children's Theatre, a New York organization devoted to "presenting professional quality theatre with and for young people." The company lists its performers alphabetically, and rotates them in various roles, a policy that prevents giving credit by name to a half-dozen young performers of exceptional ability. But I suspect that some of their names will be well known within a few years.

The music, well performed by a chamber group directed by Wayne Green, blends operatic and Broadway styles, leaning somewhat toward Broadway, and has a few pentatonic passages for Chinese flavor. It is well crafted, as the music of Strouse always is.

He has more problems in the libretto, which he wrote himself. Like Wagner, who also did his own librettos, he might profit by having a collaborator to give him a second opinion on some elements that are good in themselves, perhaps, but tend to overload the script, slow down the story, send it off on tangents, and probably make it a bit longer than an opera for children should be. In its current form, "Nightingale" is something like a Broadway show in the testing and rewriting phase on the road, before it is ready for Broadway. A bit of trimming would give it more focus and unity of impact, although the parts taken out might be missed by those who have seen the wild and woolly version unveiled at Wolf Trap.

The performance will be repeated at 2 today and tomorrow and at 8 tonight.