All is flux, the ancient Greek philosopher Heraclitus observed. A couple of thousand years later, a theater-and-dance piece is saying the same thing — but less succinctly, and with an accompanying supply of sentiment and rocks.

The rocks litter the wistful beachscape that is the dreamlike setting for “Stay,” a brave but unsatisfying meditation on loss, yearning and impermanence making its world premiere at the Lansburgh Theatre. Conceived by playwright Heather McDonald and choreographer Susan Shields, and written and directed by McDonald, this ambitious 90-minute piece attempts to speak in a new and meaningful way about some of the most basic and oft-noted truths of human experience: that change is constant and usually difficult, and that happiness, and even satisfaction, can be fleeting. Unfortunately, “Stay” — produced by Theater of the First Amendment — tackles these issues so explicitly and emphatically that the show often feels clunky and mawkish.

That’s the case even though McDonald and Shields (who choreographed the piece) eschew overarching story line in favor of diffuse poetic images and unrooted bursts of bittersweet dialogue. On a stage furnished with driftwood, abandoned suitcases and a low stone wall (James Kronzer is scenic designer), men and women with little discernible back story handle nautilus shells, or toy with smooth white rocks, or exchange remarks on subjects as varied as shattered romance, Fibonacci numbers, the inefficacy of words and the New Testament parable of the prodigal son. In one unfortunate scene, a character quotes from the Fleetwood Mac song “Landslide” — driving home the production’s life-is-transience message with all the subtlety of a sledgehammer.

Underscoring the key theme in another way are the piece’s dance sequences — stretches of choreography that are less interesting and less powerful than they might be, because they correlate so obviously with the experience of longing. Dancers whirl in delicate bemusement, or stretch their arms out in gestures of unfulfilled craving, or drape themselves against partners in poignant pas de deux. (Howard Vincent Kurtz designed the show’s casual-wear costumes.) One longs for movement that would strike a different, or more nuanced, note.

As with the dance, a mood of aching wonderment infuses the projections that sometimes bathe the back of the stage: images of light gleaming through trees, or hands writing in a journal and then tearing up the pages. Meanwhile, throughout the show, the strains of quasi-minimalist music, or the sound of the ocean, swell through the theater, shoehorning you into a pensive frame of mind, in case you weren’t there already.

“Stay” occasionally grounds its elegiac musings in humor, aided by a cast of fine actors, including John Lescault and James Whalen. Carolyn Swift offers welcome comic relief as Pheeny, who likes to invent long German-sounding words “to express the inexpressible.” Naomi Jacobson brings some levelheadedness to Eilean, who says things such as “Is nothing immutable?” And Michael Willis is enjoyably eccentric as Hymn, a guy whose idea of barroom chitchat is wondering whether Mary, Queen of Scots, was a witness to Jesus’s resurrection.

These glimpses of personality notwithstanding, the characters often feel like devices, without the solidity and narrative grounding that might make the play’s themes live theatrically. Like the pointillist images (the scarf falling from the sky, the people spinning like tops), the snippets of conversation in “Stay” fail to move McDonald and Shields’s existential concerns much beyond a state of broody abstraction. And abstractions are hard to care about.

Wren is a freelance writer.

Stay

Conceived by Heather McDonald and Susan Shields; written and directed by McDonald; choreographed by Shields; SLAM Animations by Gregory Crane; lighting design, Colin K. Bills; sound, Matthew M. Nielson; properties master, Michelle Elwyn; video technician, Aaron Fisher. With Andrew Hawkins, Aaron Ingley, Kalynn Marin, Scott Rink, Laura Urgelles, Theo Chick and Garrett Christian. Ninety minutes. Through Nov. 27 at the Lansburgh Theatre, 450 Seventh Street NW. Call 202-547-1122 or visit www.shakespearetheatre.org.