HALBERSTADT, Germany — This year, there was no Bayreuth Festival, no Mostly Mozart, Tanglewood, or Aix. But one concert, in a dilapidated medieval church in eastern Germany, could not be canceled, because it had already started — more than 18 years before the coronavirus pandemic struck. And it’s not scheduled to end until the year 2640.
On Saturday, a small crowd of mask-wearing music enthusiasts gathered in the church, St. Burchardi, in the town of Halberstadt, about 120 miles southwest of Berlin. The occasion was the first sound change in almost seven years in the slowest concert in the world: an organ recital of a piece by the American composer John Cage. It was the 14th chord change since the concert began on Sept. 5, 2001, on what would have been Cage’s 89th birthday. (He died, at 79, in 1992.)
Rainer Neugebauer, a retired social sciences professor who runs the John Cage Organ Foundation in Halberstadt, the body that organizes the performance, told the crowd on Saturday that, “Unlike the Olympics or the World Economic Forum in Davos, we couldn’t postpone it.”
“The chord change had to go ahead,” he said. “It’s in the score.”
Cage first wrote the piece, for piano, in 1985; the tempo instruction was, “As slow as possible.” He then reworked it for the organ in 1987, and it became known as “Organ²/ASLSP.”
But that raised questions. On piano, the sound fades after a key is hit; on the organ, notes can be held indefinitely. Or can they? What about when the organist needs to eat, or go to the bathroom? Or dies?
Those questions occupied a group of composers, organists, musicologists and philosophers, some of whom had worked with Cage, at a conference in the town of Trossingen, in southern Germany, in 1998. They developed the idea of a performance calibrated to the life expectancy of an organ. The first modern keyboard organ is thought to have been built in Halberstadt in 1361, 639 years before the turn of the 21st century — so they decided the performance would last for 639 years.
Even then, the idea that the performance would make it to 2640 was radically optimistic: That will require handovers between generations, and it will take effort and money. And that seems even more unlikely now, as the pandemic makes us realize life’s fragility, and the threat of climate change puts human survival in question.
But a lot can change with the passing of the years, as the history of the St. Burchardi church shows: It was built around 1050; partially destroyed in the Thirty Years’ War; deconsecrated in 1810 by Jérôme Bonaparte, brother of Napoleon; and since then has served as a barn, a distillery and a sty.
Its organ is not a standard keyboard-operated instrument. Pipes tuned for the notes of the score are added or subtracted as required at each sound change. There is no organist requiring bathroom breaks; the pedals that activate the pipes are held down by sandbags.
The ceremony to accompany each change has become a ritual for the piece’s fans. While some regular attendees from abroad were unable to make it on Saturday because of the pandemic, there were spectators from countries including the Czech Republic and Denmark. The church’s small gift shop did a brisk business in commemorative masks.
With the number of people allowed into the church restricted, some followed on a large screen in the courtyard outside. At 3 p.m., the composer Julian Lembke and the soprano Johanna Vargas, both wearing white gloves, lowered two new pipes onto the body of the organ, which sounded a G sharp and an E. These created a new, seven-note chord, together with the five notes that have been sounding since October 2013: C, D flat, D sharp, A sharp and E.
Mr. Lembke said in an interview afterward that he noted “a new softness” to the chord, as well as a denser sound.
The epic performance has helped put Halberstadt on the map, Mr. Neugebauer said. In common with many other eastern German towns, Halberstadt’s population is dwindling and aging, but Mr. Neugebauer estimated that some 140,000 people had visited to hear the work since it began.
“It’s not a project for the masses,” he said. “But it’s a crystallization point for contemporary art. It brings interesting people to Halberstadt.”
Andreas Henke, the town’s mayor, said that most of Halberstadt’s inhabitants probably didn’t even know about the piece, or, if they did, they referred to it as “that cacophony.” But, he added, “John Cage carries Halberstadt’s name out into the world.”
He said the performance raises “philosophical questions about how we confront time.”
“We are all so consumed by our daily working lives,” he said. “This forces us to stand back and slow down.”
“It is very special to be a part of an art project that will connect generations and last for generations,” Mr. Henke added. He said that it was “his great hope” that the project would make it to 2640.
The most immediate threat to the project is a banal one that has plagued it since the start: running out of money. “Sometimes we say this project needs only time and air, but we have to talk about money too,” Mr. Neugebauer said.
Day-to-day running costs are financed almost exclusively by private donors, he said, who can purchase a plaque displayed in the church representing a year in which the piece will play.
The year 2580, for example, has been acquired by a couple identified as Silvia and Jörg, to mark their 600th wedding anniversary. The Dresdner Kreuzchor, a famous boys’ choir in Dresden, Germany, has bagged 2539 to commemorate what will be the 1,000th anniversary of a central local event in the history of the Protestant Reformation. About 1 million euros, around $1.2 million, has been raised this way, Mr. Neugebauer said, but recently, donations have been dwindling.
Mr. Neugebauer said the project was a hand-to-mouth operation, reliant on volunteers, including himself.
“In three-and-a-half years, I will turn 70, and I would like to stop,” he said. “It would be great to hand it over to the next generation in good shape.”
If all goes according to plan, it will be the first handover of many.