The composer’s “Oratorio for Living Things,” forced to shut down because of the pandemic, returns to the Ars Nova stage in Manhattan.On a strangely comforting morning in early March, the composer Heather Christian made her way to Ars Nova’s space in Greenwich Village, Manhattan, for the first time in two years. The bright sun, radiating the warmth of a spring day, was enough to momentarily make her forget she was freezing. Once inside, she re-encountered the set for her delicately epic choral piece “Oratorio for Living Things,” which had two preview performances before the pandemic hit, and is back, running through April 17.“I felt the weight of time,” she said during a recent conversation over Zoom, reflecting on her return to the theater. “It was the weight of expectation or even the grief of the last time I was in that space.”It was only fitting that time felt like Christian’s companion, since “Oratorio for Living Things,” in the words of its creator, is a study of time “in three different scales: the quantum scale, the human scale and the cosmic scale.”To achieve this, she said she tried to find parallels between the ways in which particles move, for example, and the way in which a fugue is structured, or by examining cosmic violence (the Big Bang) and linking it to human trauma.Gerianne Pérez, center, in “Oratorio for Living Things” at Greenwich House Theater in March 2020, shortly before the premiere run shut down.Sara Krulwich/The New York TimesThen, to explain these concepts on an emotional level, she collected hundreds of voice mail messages that she had solicited from strangers, inviting them to share a memory anonymously. (“I left business cards everywhere!” she said with a laugh.) These delicious recollections — of transporting bags of groceries on a sleigh in Moscow, or knowing that someone’s mother “will bring my baby brother with her” when she leaves the hospital — make up the second act.As for the musical composition, performed by an orchestra of six, “Oratorio” layers myriad genres — gospel, jazz, Baroque and a range of pop styles — to create harmony where cacophony might otherwise exist.“The more we sing these songs and say these words,” said Onyie Nwachukwu, one of the 12 singers who bring the piece to life, “the more I’m acutely aware of the almost fantastic nature of humans and everything that’s around us.”The show’s director, Lee Sunday Evans, envisioned the production as if set in a Quaker meeting house “where there’s no pulpit or proscenium and so the music wants to be amongst us.” Performers move throughout the space gently interacting with audience members, almost inviting them to sing along.“I knew I wanted to do a piece about time,” Christian, 40, explained. “Music itself is a study of time, a dissertation on how time moves in a specific way.” She tried dissecting Carl Orff’s cantata “Carmina Burana,” a celebration of earthly passions that she describes as “spaghetti exploding out of the bowl.” It has been a favorite of hers since high school because of its mysteriousness — it asks big questions without offering an answer.A self-described cultural omnivore who finds as much wisdom in “The Golden Girls” as Bach’s compositions, Christian revisited Orff while reading Carlo Rovelli’s “The Order of Time,” about time in physics, and rewatched old episodes of Carl Sagan’s “Cosmos.” Her fascination with how they all explained complex subjects in digestible ways eventually resulted in an eureka moment: She would do the same with a musical piece. And that’s when she started working on “Oratorio.” (The libretto is dedicated to the three Carls.)Christian composes by ear. “Things come to me all at once,” she said. But lacking a consistent practice for transcribing her work, she found a priceless collaborator in the music director Ben Moss, who also performs in “Oratorio.” Moss came in during an early workshop of the piece in 2018 and offered to help with the transcription. At the time, Christian had the skeleton of the work, Moss added the minutiae. He said it felt as if he were “crawling inside of her mind and her musical and poetic imagination.”Using voice notes and memos, Christian conveys her intentions to her collaborators, making them an essential part of the process. “I wish we recorded some of the sessions of her explaining things and her whys and hows because it in and of itself is artistry,” said Nwachukwu, who also appeared in a 2019 workshop of Christian’s “Annie Salem: An American Tale” at Vassar’s Powerhouse Theater. She said she found herself approaching theater from a new perspective: “less restrictive and structured” than what she was accustomed to in opera and more traditional musicals. “What Heather asked of me was to go to a place that was somewhat uncomfortable,” she recalled, “where the first thing I had to do was throw away convention.”From left, Amber Gray, Christian at the piano and Libby King and Brian Hastert embracing in “Mission Drift” at the Connelly Theater in Manhattan.Chang W. Lee/The New York TimesRachel Chavkin, the Tony-winning director of “Hadestown” who oversaw the workshop of “Salem,” described Christian’s music as “somewhere between a creature howling at the moon and the sound of the moon itself.” Her music, she continued, “isn’t about furthering story, each song is a bit more like a spiritual or emotional happening than a story beat.”Chavkin began collaborating with Christian in 2008 when they created a musical called “Mission Drift,” a show about the recession and America’s rapacious brand of capitalism. Every time they work together, Chavkin said, “I can see my own experience with the possibilities of these forms.” She added: “Heather is inventing the wheel for herself.”FOUR DAYS BEFORE theaters in New York shut down, I attended the last dress rehearsal for “Oratorio.” I distinctly remember leaving the theater feeling as if I had witnessed a work that successfully established a dialogue between the sacred and the mundane, between the invisible and what we grasp with our senses. In many ways, it left me open to viewing the pandemic as an opportunity to find wonder and solace in the things we often take for granted.During that forced break in 2020, Christian herself found and made music out of things she’d never tried before. “I was swimming in a sea of first drafts,” she said, laughing, “but I also got chickens and decided to learn how to garden in a serious way.” Spending time with her husband at home in Beacon, N.Y., she also took to self-reflection. “I tried to investigate my relationship to ambition and slow down, especially because all my shows are about exactly those things,” she added.Born in New Orleans, Christian was raised in what she called “avant-garde Catholicism.” At 11, she became a cantor in Natchez, Miss., where her family had moved when she was 3. But soon “the functional magic of religion lost its mysticism,” she explained. She recalled being behind the scenes and a time when she saw “a priest pick a wedgie in the middle of the consecration of the host.” Suddenly, it was all theater, a new kind of sacred space.“I honestly think it’s going to take a little bit of work for me, and for people, to reimagine the performance space as a womb and a safe space,” Christian said.Tony Cenicola/The New York TimesShe sought formal education in musical theater at New York University’s Tisch School of the Arts, where her acting teacher observed she was quite complex and wisely encouraged her to join the experimental theater wing.Christian describes herself as someone who “would go insane if you took away my pens and microphones.” During lockdown, she found new channels for her creativity in projects like “I Am Sending You the Sacred Face,” a one-person musical about Mother Teresa in collaboration with Joshua William Gelb, and even became a foley artist in order to adapt her show “Animal Wisdom,” an autobiographical cabaret, for film, which she hopes will be picked up by distributors. “I’m incredibly prolific, and I don’t say that as a brag,” she confessed, “it’s just how I function.”She explained that she needs to find functionality in her art, returning to work in “Oratorio” presents a new set of challenges. “Initially I made a Rorschach test for whatever people brought into it,” she said, but now she wants to “provide people with some optimism.”“I honestly think it’s going to take a little bit of work for me, and for people, to reimagine the performance space as a womb and a safe space,” Christian said. “The lucky thing is that with theater all it takes is lighting and sound and bodies to completely transform a space.”She added: “I forgot how much I love people, how much I thrive around people.” More