The hallucinations began around 4 a.m. — nine hours and not even halfway through Erik Satie’s “Vexations,” the devilishly beguiling piece that, depending on whom you ask, is either a step toward Zen enlightenment or the longest joke in music history.

I was at the Guggenheim Museum for a marathon performance of “Vexations” at the Peter B. Lewis Theater, a subterranean space with no cell service or views of the outside world. The seats weren’t comfortable enough for sleeping, and the chilly temperature left me torturously alert for the entire concert, which began at 7 p.m. on Tuesday and ended around 1:30 p.m. the following day.

I felt, by turns, agitated, frozen and delirious. But I also left with the clearest mind and best hearing I’ve ever known. Here’s how it happened.

7 P.M. The avant-garde composer Christian Wolff played the first shift of “Vexations,” which is both simple and bafflingly difficult. Written in 1893, the score is just four lines of music, but Satie’s directions suggest it should be played slowly — and repeated 840 times. Many pianists believe that the piece somehow defies memorization.

The score of “Vexations.”

 

Mr. Wolff was among the small group of musicians who played in a notable marathon of “Vexations” organized by John Cage in 1963. That performance, which lasted nearly 19 hours, has become the stuff of legend; The New York Times opened its review with: “Whatever it was, it made musical history.”

Four of Cage’s pianists were at the Guggenheim this week: Mr. Wolff, Philip Corner, David Del Tredici and Joshua Rifkin. After leaving the stage, Mr. Wolff walked to the green room, where Mr. Del Tredici stood for a hug and yelled, “Oh my god, we’re still alive!” 

There was no green room at the humble Pocket Theater in 1963, Mr. Wolff later told me. They had some pillows backstage, he said, but the event was casual. Some players even left at one point to have dinner in Chinatown.

John Cale, in front on the piano bench, and John Cage, behind him, at the piano during the 1963 performance of “Vexations” at the Pocket Theater in New York. CreditEddie Hausner/The New York Times

 

In a way, Mr. Wolff said, it was good that a “Vexations” marathon had found its way into a museum. “But you don’t want the piece to get too socialized,” he added.

As I walked back into the Guggenheim’s theater, about 100 people were watching Mr. Corner at the piano, where sheet music shared the stand with two iPads. Onstage there were also official counters who kept the running tally. These counters may have had the most difficult job of the night. Keeping track of the repetitions required unrelenting attention, with no room for daydreaming. One of them, Thomas Delvito, spent six hours total staring at four lines of music.

9 P.M. Many audience members welcomed distractions. Couples wrote to each other in notebooks. One young man kept his own tally of repetitions. The Guggenheim staged “Vexations” as part of the exhibition “Mystical Symbolism: The Salon de la Rose + Croix in Paris, 1892-1897,” so I perused the catalog.

The book referred to the salon as “a call to arms for the worship of beauty.” It was founded by Joséphin Péladan, a walking caricature of decadence. He was close with Satie, who wrote music for his plays and was the official composer of the first salon, in 1892.

But then they had a falling out. Some think “Vexations” is a rebellion against everything Péladan stood for, especially the Romantic grandeur of Richard Wagner’s operas. (Péladan was said to have been inspired to create the salon after seeing “Parsifal” at Bayreuth.) Others say “Vexations” is a hopeless breakup ballad. It could also have just been a private joke.

No one will ever know; the piece was never performed in Satie’s lifetime and wasn’t discovered until the 1940s, long after his death.

In 1970, Peter Evans nearly lost his mind while attempting all of “Vexations” on his own. He quit after 595 repetitions and was said to have had evil thoughts and visions. Mr. Evans later claimed that pianists who take on the piece “do so at their own great peril.”

Timo Andres, the pianist and composer, stepped onstage at 2:20 a.m. Earlier, he had told me that he tends to think of all music sculpturally; “Vexations,” he said, “takes on a very dark presence.”

Christian Wolff playing “Vexations” as Philip Corner waited on deck to his left. On the right, Ai Isshiki kept a running tally of the 840 repetitions of the piece. CreditEnid Alvarez/SRGF

 

3 A.M. In the museum’s café, I met René Diaz, a 28-year-old biochemistry student at Hunter College who had been working behind the counter since 2 p.m. “Vexations” boomed out of loudspeakers overhead.

“I’ve been cleaning and trying not to go crazy,” he said. “Your brain can only take so much of this.”

4 A.M. The music began to take shape in strange ways. It was a beam of light bouncing off the walls of the theater, seeking some sort of unattainable resolution. It was a difficult parking job, with the car backing in and out in rhythm. When my eyes closed briefly, I saw a face that reminded me of Tilda Swinton’s, which made me think of that time she slept in a glass box and called it performance art. I wished I could do the same.

Clee McCracken, a 24-year-old who had flown in from Chicago just for this concert, wrapped himself in a fleece blanket on the floor but never slept. He stayed until the very end and said he would happily do it again.

7 A.M. “Vexations” is a highly slippery piece: When I went to the bathroom, I noticed I couldn’t remember its singsong melody. Taka Kigawa, who took on three shifts, told me you “can’t think about anything else” while playing it.

11 A.M. After 16 hours, I finally realized three notes in “Vexations” sound exactly like the NBC theme. From that moment on, it was all I could hear.

1 P.M. When Mr. Corner left the stage for the last time, he shook Mr. Wolff’s hand and said, “Well, the deed is done.” Mr. Rifkin played the 840th repetition, then lifted his fingers from the keys. Out of inertia or confusion or both, the audience didn’t applaud until he stood up.

2 P.M. One of the first things I saw after stepping outside for the first time in 19 hours was a Mister Softee truck. I wondered whether that ubiquitous jingle was like “Vexations” for the driver.

Walking through Central Park, my senses were sharper than ever. Leaves sounded like percussion in the wind, and Bethesda Fountain sounded like a jet. But nothing sounded better than my bed.