For four nights before the concert, the old master had trouble sleeping. In his dreams, he was haunted by defeat after defeat — a failed exam, a knockout in the boxing ring. During the day, an upset stomach reduced his diet to gentle soup.

But now, Sadiq Fitrat Nashenas, 88, one of the last living stars of a golden era for Afghan music, gingerly made his way through the crowd, after nearly 20 years away from the public stage. He had the thick spectacles of a long-retired professor, the neatly trimmed mustache and elegant outfit of a gentleman of a bygone era, and the shyness of an artist still uncomfortable with adulation after a lifetime of performance.

The audience stood in applause. Mr. Nashenas gently raised his hands and blew kiss after kiss, until he was helped by the elbow onto the stage and seated behind the harmonium he would play as he sang for the next three hours.

“Life is a stage of artistry,” he intoned, opening the night with Farsi verse. His booming voice put to rest rumors that age had brought a tremble to it. “Everyone comes, recites their song, and departs. But the stage always remains.”

Mr. Nashenas’s own life and artistry speak to the Afghanistan he left behind,and one that could have been.

There is a timelessness, a sense of continuity, to his music: poems penned half a millennium ago, set to rhythmic arrangements hundreds of years old, presented to a contemporary audience in several languages of West and South Asia. The music he developed, untouched by the region’s modern political and religious fractures, blended the great Farsi poetic tradition of Iran, the folk and oral heritage of Afghanistan and the vastness of India’s classical music.

He gave his concert last month in the Netherlands, far from an Afghanistan where, since the return of Taliban rule, public music is once again banned, musical instruments are smashed by state agents and musicians are hounded.

The venue was a “party center” tucked between auto dealerships in Beverwijk, a small town just outside Amsterdam. The place had the feel of a Kabul wedding hall: bright chandeliers; waist-high plastic flowers that had to be removed from the tables so you could see Mr. Nashenas and the band. Flasks of green tea and bowls of sugarcoated almonds made their way from a tea bar in a corner.

Mr. Nashenas himself left Afghanistan in 1991, in the final days of its Communist government. He and his family were packed into a pickup truck, navigating through insurgent checkpoints, bound for Pakistan and, eventually, London.

He would never return. His heartbreak and anger were simply too deep.

But in his grief, music remained a refuge. He recorded and performed for large audiences in the United States, Europe and Australia. Eventually, advancing age and messy diaspora politics turned him away from bigger concerts, but he kept playing for himself and a small circle of friends. He decided to perform last month mostly to see if he still had it in him.

“I was just trying to hold on to my music, because music takes me to God, to the heavens,” he said. “Life without music is a mistake.”

A Secret

He was born Mohammed Sadiq Habibi in the southern Afghan province of Kandahar in 1935 — a time, he says, when Kandahar “had one doctor and two homeopaths.” The conservative Habibi family was well known. Seven generations of its men before him had trained as Islamic scholars, known as Mawlawis.

But his father, Mawlawi Mohammed Rafiq Habibi, was a conflicted man.

Although he had studied as a religious scholar, he worked as a bank clerk and was for years the Afghan state bank’s representative in Karachi, which was then a port city in undivided India. He dressed in suits and ties and was open to debating theological questions with his son about the existence of God.

It was his mother, though, who opened new worlds for him.

Some of his earliest memories involve listening to his mother, Bibi Hazrata, and other women of the family in Arghandab, a district of pomegranates and vineyards, as they sang folk songs at weddings and family gatherings. His mother was also his early interpreter of poetic verse. She did not have formal schooling, but classical poetry in those times was a pillar of education in the mosque and at home.

“My mother had a lot of interest in poetry, and knew the meanings well,” he said.

One of the first recordings he made, years later, for Radio Afghanistan was of a Pashto folk song he had heard as a child, which his mother helped him understand. On a bus ride from Kandahar to Karachi, the conductor softly sang the song.

I am going to visit my beloved today

May God shorten these earthly ropes.

The boy tugged at his mother and asked what “earthly ropes” meant. She described God as a puppet master of sorts, sitting in the heavens.

“All these distances in the world — the threads, the ropes are in God’s hand,” she told him. “Whenever he wants to connect the lover with the beloved, brother with brother, husband with wife, he pulls the strings and the distances disappear.”

As he searched for a voice and an identity as a youth, he wrote essays and poems. “No one noticed,” he said.

Until one day when, at 15, he was singing a song as he bathed. His mother heard him and asked him to sing it again.

“She liked it, and tears started rolling down her face,” he said.

“It was at that moment that I realized: I have found my path.”

Much of his early professional musical life was a secret. He finished his university degree, found a desk job at Radio Afghanistan and used that to get behind the microphone and record songs. For four years, even as his songs became famous, no one in the family knew the voice on the radio was his.

He had taken a stage name: Nashenas, which loosely translates as “unknown,” and which he would adopt as his surname.

But one day at the bank, a clerk who had learned the true identity of the new radio star congratulated Mr. Nashenas’s father on his son’s success. His father confronted him, not happy that something so big had been kept from him for so long.

“I said, ‘You are prejudiced against music; I was afraid of that,’” Mr. Nashenas said he replied.

His father denied that, but told his son he was worried that he could face humiliation in a society where “music and dance will take another 200 years before it is seen in the fine arts.”

“He was a man of his times, and I was of mine,” Mr. Nashenas said.

Neither of his parents lived to see the peak of his fame. But Mr. Nashenas knew that his father had come around to his choice, in his own quiet and proud way.

On his deathbed, his father kept a radio next to him at low volume. He said he was listening for the news. But Mr. Nashenas’s mother later told him that his father had been keeping an ear out for his songs.

The same contradictions that marked his father’s life went even deeper in Mr. Nashenas’s own: a secular man in a profoundly religious family; a rationalist in a society trapped in tribal ways. Mr. Nashenas’s formative education took place in the Soviet Union. At heart, he became a liberal.

After earning a doctorate in literature in Moscow, he worked as a civil servant and a diplomat. When Afghanistan began to disintegrate in the late 1980s and early 1990s, he had just returned from a diplomatic posting in Moscow. Kabul, where a Soviet-backed government was in power, was encircled by the mujahedeen, the religious guerrillas supported by the Americans. The city was choked, its residents fleeing to escape the constant barrage of insurgent missiles and the long lines at bakeries running out of bread.

Mr. Nashenas and his family left everything behind, including his savings in the bank and the money from the sale of their house. Just outside the Kabul city gates, a guerrilla cornered the famous musician, who had grown out his beard and put on dirty clothes as a disguise.

“Where are you coming from?”

“Kabul.”

“What do you do there?”

“I am retired.”

“What did you do before your retirement?”

When Mr. Nashenas lost patience and asked the young man to leave him alone, the fighter lifted his gun to his chest. Finger on the trigger, the guerrilla accused him of being a “communist and an infidel.” He could easily kill him right there and no one would care, the fighter told him.

Mr. Nashenas made it out of Afghanistan, settling in London with his family of five. He would not return, even during the 20-year American presence, a time when many believed in the promise of a new beginning. It was as if he could see that what was being built would not last.

“I am aggrieved by them,” he told an interviewer earlier this year. “The country owes me my 40 years’ pension; they didn’t even give me that.”

If he went back to Kabul now, he would not recognize it — not its streets, and perhaps not its people or their ways. As he withdrew into his corner of seclusion in London, his homeland was forever changed by three decades of bloody turmoil.

But he will sing for Afghanistan as long as he has music in him.

“It’s a connection of blood,” he said.

A Full Heart

Bano Bahar, a middle-aged artist with dirty-blond hair and a big infectious laugh, took her seat at the table right at the foot of the stage. She said that while she had listened to Mr. Nashenas’s music for decades, this was the first time she was getting to see him perform live.

Ms. Bahar kept scanning the corners of the hall, asking if the old master was there yet. She was a woman on a mission: She wanted to perform a duet with Mr. Nashenas. His manager said absolutely not.

“I will do whatever it takes to make it happen,” the woman on a mission said. “I will kick and scream like a child.”

Next to her at the table was an old leftist journalist, who had also been in exile for decades. He wore a beret, a goatee and a mischievous smile. His claim to fame: Three presidents had tried to kill him, he said, and he had been poisoned six times. (Another claim to fame: He was part of a youth group that pinned a picture of a communist president to the butt of a dog and unleashed it into the city. “It took a whole military squad to chase the dog,” he laughed.)

The crowd stood as Mr. Nashenas appeared at the top of the stairs, some coming forward to kiss his hands in reverence.

He took his seat behind the harmonium that had been part of his life for 70 years. His hands trembled as he tried to arrange his handwritten notes and lyrics. He was visibly nervous — and irritated by the chaos as well-wishers and prominent exiles welcomed him in speeches.

“Music will not die in Afghanistan, poetry will not die in Afghanistan,” said Ahmad Shah Farhood, a historian. “Despite all the oppressive regimes, music will live on.”

Finally, Mr. Nashenas began the performance, accompanied by a four-man band of exiles from all over Europe. There had been no rehearsals.

At the end of the first song, Mr. Nashenas gently threw his hands up in acknowledgment of the applause.

“Don’t forget that I am 88 years old — do not expect the voice of a 25-year-old,” he joked.

Ms. Bahar was so consumed, so in awe, that she forgot about her demand for a duet. With one hand, she held her phone and broadcast the concert on Facebook. With the other, she tapped the table to the beat. In between, she wiped the tears that mixed with her mascara.

Sometimes, the old master got stuck on a verse, forgetting a line in one of his 600 songs. As he searched through his papers, his apprentice, Arash Forogh, who was playing backup harmonium, picked up the song’s thread and completed the verse. Mr. Nashenas smiled in appreciation.

On two occasions when he couldn’t remember the verse, he threw it to the audience: “Does anyone remember the last verse?”

Of course they did.

Sometimes, his hands let go of the harmonium and his fingers danced to the tabla’s beat, to the rhythm of the words he sang. An old master in a little trance. Other times, he cupped the microphone tightly in both hands — an aged rock star lost in the crescendo.

At least once, when the jitters were washed away by the audience’s love, he looked up to the sky. Later, he described it as the silent gratitude of a secular man to the powers that might be out there, “but that our mind cannot comprehend.”

Far away from the region that shaped him, far away from the homeland lost to him so long ago, in a wedding hall tucked between car dealerships, his heart was full.

To loud applause, the old master said: “I will never forget this night in my life.”