The story of how John Jahnke found Susan Sontag’s lost playlet “A Parsifal” (“lost” in the sense that it only existed in an out-of-print magazine) sounds a bit like its own Grail story. According to legend, the Grail likes to pop up out of nowhere, reappearing when conditions are right and its guardians are well armed. And Mr. Jahnke, rooting through old magazines in a used bookshop, must have seemed like just such a guardian. His earlier work, like “The Shady Maids of Haiti” and “Lola Montez in Bavaria,” echoed Sontag’s own qualities – impressively intellectual while celebrating a camp aesthetic. But in “A Parsifal,” now at P.S. 122, we see the many, many slips ‘twixt holy cup and lip.

Sontag wrote the six-page, expressionist amuse-bouche as a gift for Robert Wilson after seeing his production of the Wagner opera. So if viewers aren’t at least passingly familiar with the original tale, “A Parsifal” will be nearly incomprehensible. The story of a holy fool (prone to getting lost) who withstands temptation to reclaim a sacred spear is here boiled down to its most basic ingredients, some of which are never identified. Then Mr. Jahnke filters those ingredients through a “Pink Narcissus” landscape, all dreamy pastels and sculpted torsos – slowing the Sontag text to an excruciating crawl.

After waving away a sadistically aimed burst of chemical fog, we meet Parsifal (Gardiner Comfort) wandering around naked in a forest. Watching over him is an extremely bossy ostrich (Charles Ludlam’s iconic muse, Black-Eyed Susan) who seems determined to drive him on to greatness. This feathered chaperone can be quite tart with Parsifal; she warns him that an ostrich will destroy her eggs if they addle. Certainly Mr. Comfort’s hero seems addle-ridden enough to warrant a good swift kick in the nonexistent pants.

Joining the Grail soldiers, and occasionally enjoying a tryst with the mysterious Kundry (Okwui Okpokwasili), Parsifal blithely continues on a quest he doesn’t seem to understand. He delivers a press conference celebrating his ignorance (“I read as little as possible; I trust what I feel”), but blunders on to success nonetheless.

Mr. Jahnke’s laudable choice to remain true to Sontag’s lyrical imagery stumbles over major blunders of execution. In theory the all-white set and Vangelis-like music should make Parsifal’s world sublime and otherworldly. But in practice, this clunky, woodenly acted production looks like heaven on the cheap.

Embracing its limited means, however, has done a world of good for “Thousand Years Waiting,” the show in P.S. 122’s smaller, downstairs space. Chiori Miyagawa, whose contribution to last season’s “The Antigone Project” was one of that evening’s highlights, blends together two millennium-old Japanese writings with her own modern sensibility. In her newest piece, a young woman living in New York begins reading both the “Sarashina Diary” and Lady Murasaki’s “The Tale of Genji,” linking her own experience to that of the women from 1,000 years ago.

The piece itself has lightness and movement – Ms. Miyagawa pokes gentle fun at “The Tale of Genji” and its womanizing, oblivious hero. In Sophia Skiles, who plays the author of the Sarashina diary from adolescence to old age, the production finds a warm and sympathetic center. But it is director Sonoko Kawahara’s casting of other “actors,” Masaya Kiritake and her female puppet, that completely transcends the sweet, girl-power message of the rest of the show. Dancing together to Bruce Odland’s plangent music, puppeteer and puppet – sometimes draped in chiffon, sometimes appearing abruptly from behind black drapes – leave the others in their dust. If only Mr. Jahnke had coaxed expressiveness out of his live actors the way Ms. Kiritake does from her wooden doll – but for that we may have to wait another thousand years.

“A Parsifal” until March 5,”Thousand Years Waiting” until March 12 (150 First Avenue at 9th Street, 212-352-3101).