The National Theatre of the Deaf has turned to Arthurian legend, albeit with a wink or two, for its latest endeavor, "Parzival," which opened a six-day run last night in the Kennedy Center's Terrace Theater. The subtitle, "From the Horse's Mouth," indicates the playful tone, although neither title nor subtitle takes into account the elements of story theater, group therapy and general consciousness-raising that also find their way into the evening.

As usual, the members of this unique troupe use sign language and appear to be snatching "words" out of thin air with their hands, a graceful and theatrical spectacle in itself. A few of the actors utter random lines, but the main burden of translation passes to two speaking actors in the cast. What the National Theatre of the Deaf offers the general patron is the chance to "see" speech and "hear" with the eyes.

However, I'm not sure that "Parzival," for all its moments of shining invention, isn't something of a muddle. Written by Shanny Mow and David Hays, it is occupied both with the quest of the title character (William Seago) for the Holy Grail and the contemporary quests of the various company members, who break ranks periodically to relate bits of their own autobiography. The Arthurian end of things is rendered mostly in mock heroic style, while the present-day quests are of the confessional/poetical persuasion. Lyrical as sign language appears to the outsider, "Parzival" in translation doesn't always manage to avoid some of the thumping who-am-I-where-am-I-going? cliche's that plague our world at large.

It is probably wiser to concentrate on the visual aspect of the production, which unfolds before a series of panels that could have been painted by Douanier Rousseau. The naive Parzival and his horse Nevefere (Mike Lamitola) sally forth, encountering enchantment, rival knights, a swooping hawk and a petrified rabbit (both incarnated simultaneously by one and the same actor), a magic bed and a great lumbering monster (two actors, seesawing on a third).

There are no props. Those that are not mimed are portrayed by the cast, and that includes the sword in the stone with which Parzival is dubbed a knight. Some of this is merely cleverness, but there is a beheading in the second act, depicted with a sudden shriek and two soaring ribbons of red, that is worthy of the Grand Kabuki. To the extent that it allows itself to be boldly non-naturalistic and to search out the visual equivalent of dramatic effects normally rendered in sound, the National Theatre of the Deaf is a welcome extension of our theatrical boundaries.

When the production dips into the personal quests of its cast members, however, "Parzival" takes on a sociological tone that is less compelling. This is not to minimize the sincerity of the various confessions, which are marked by an absence of self-pity and in some instances by a fair amount of humor (to wit, the young actress who decided to teach her pet parrot to speak and suddenly found it outstripping her). What the National Theatre of the Deaf is really doing at moments like these, though, is explaining to us why and how it must be different from other companies.

The point, it seems to me, scarcely need be made. To be told by a deaf actor that at a tender age "I lost my doorway into your world" is one thing. To be shown with the twinkling of hands raised on high the magic and wonder of starlight is quite another. Both moments may be rooted in the circumstances of deafness. But it's the starlight that is truly moving. PARZIVAL. By Shanny Mows and David Hays. Directed by Edmund Waterstreet and John Broome; sets, Charles Baird; costumes, Fred Voelpel. With Lizette Smith, Bari K. Waterford, Mike Lamitola, William Seago, Andy Vasnick, Adrian Blue. At the Kennedy Center Terrace Theater through March 12.