Members of the string ensemble A Far Cry pose for a portrait. The group performed Saturday at the Sixth and I Synagogue in Washington. (Yoon S. Byun)

What a week it has been around here for song cycles: two very different performances at the Kennedy Center of Bernstein’s 1977 “Songfest” (one composer, many poets and many singers) and then, on Saturday at the Sixth and I Synagogue, under the auspices of Washington Performing Arts, the world premiere of “The Blue Hour,” a collaborative endeavor of five composers but just one poet, one singer and the extraordinary string ensemble A Far Cry.

The Bernstein cycle looks back on 300 years of American culture. Poet Carolyn Forché’s poem “On Earth,” which is the text for “The Blue Hour,” looks back on a life as it nears its end: “Open the book on what happened,” she writes, and then, “I try to keep from wanting the morphine. I pray with both hands.” ”

But “The Blue Hour” is not a morbid retrospective, nor is it a linear one. As one’s imagination is apt to do, the poet’s mind jumps around from image to image and from interior to exterior reality. To keep all this in order, literally, Forché has used an ancient organizing tool, the alphabet, to impose structure on her mental ramblings. The “L” verse, for instance, begins with “library, lilac, linens, litany” and then wanders to personal reflections on light, from its glory “impaled on peaks” to the grubby “light of cinder blocks, meal trays.” Sometimes the alphabet veers into Latin and sometimes into French, but its very waywardness, in this setting, has a strangely calming effect.

Working together, composers Rachel Grimes, Sarah Kirkland Snider, Angélica Negrón, Shara Nova and Caroline Shaw, the Grammy Award-winning singer Luciana Souza and the 18 string players of A Far Cry have come up with a gorgeous and remarkably unified work. The composers split responsibility for the 38 songs pretty evenly and seemed to have come to an understanding that, except for occasional instrumental drama (bits of dancing Bach, feathery “hair” images, a fountain of whirling arpeggios, the rasp of graveyard dust and one siege of tense angst early on), the strings would provide a comfortable and lyrical world for the poet’s mind to inhabit.

Vocally, “The Blue Hour” is a singer’s dream (Souza’s influence?). Lyrical and, for the most part, quiet, the music lies right in her mezzo range’s sweet spot and gave her endless opportunities for nuance, which she took on magnificently — her stiletto-sharp disdain on the phrase “question after question” (the Q’s in the alphabet, along with quiescent, quiet, quinine and quivering) was withering.

Souza knows just how to use a mic and, standing as she was in the middle of the strings conducting to herself, she was the vibrato-less focal point of some of the most exquisite ensemble I’ve ever heard. A Far Cry prides itself on its democratic, conductor-less music-making, and if this is an example of how they do it, they have a lot to be proud of.

The 70-minute reverie closed brilliantly with a quiet, simple round on the text “all of this must remain” and drifted off as the lights dimmed. Theatrical? Maybe, but here very effective.