River.

"But what is it about?" you might ask, irreligiously, of River, Eiko and Koma's aquatic set piece based on a dance that premiered last August in the Delaware River. Part of the answer to the question may lie in River's resolutely antitheatrical momentum, in a slowness of pulse that suggests a dance at rest, nearly submerged in the life of nature. River may not be "about" anything more -- or less -- than another river could be. Surely the dance means no less when performed in Brooklyn.

More antitheatrical than anything else in the piece is the substantial overture of silence that begins the dance -- which is also silent visually at first, opening in a prolonged state of gloom that is lightened only very gradually. The odd cadence produced by the general murk seems meant not to amuse or alienate, but to insist that observers experience the dance, instead of just observe it. Even when at last it's fully perceptible, River remains decidedly amphibian, evoking in its onstage stream and scrappy shoreline a condition of in-betweenness that could be called physical or metaphysical.

The action: Eiko and Koma drift half-disembodied through and near the river, embryonic survivors of a world that may have grown too old to sustain them. Their intimate, broken gestures seem timeless and obscurely wounded. indeed, midway through, Koma's role seems to shift as he assumes a caretaker's responsibility for Eiko, guiding the tidal unconcern of her listless yet instinctively willful floating body. Eventually, they gravitate to a downed tangle of tree limbs (sculpted by Judd Weisberg); later, he hoists the tangle in a slippery epiphany of fitful stasis. Pollywoggish, they eventually exit, though the trickling tempo of the rest of the seventy-five-minute piece would seem to forbid such decisive action.

The microcosmic languor of the landscape is dramatic, partly because of Eiko and Koma's spectacularly successful collaboration with the Kronos Quartet (playing onstage) and composer Somei Satoh, whose mistily pining tones ebbed toward a resolution poignantly never meant to occur. Satoh's ode to rippling entropy (exemplified, somehow, by a passage in which the Kronos cellist played, solo, only high notes) was sweet, sad, and intensely emotional for all its abstractness.

Satoh's sounds seemed to evoke a metaphor that had no name, like the dance itself. Presented as part of the Brooklyn Academy of Music's Next Wave Festival, River is "about" unconscious discovery, cellular gravity, the lure of an epic without real events.