Hollander is not naive. He subscribes to Leonard Bernstein's philosophy: "Art never stopped a war… art cannot change events. But it can change people." Battery Dance Company's educational program Dancing to Connect has been conducted in more than 40 conflict zones, including Iraqi Kurdistan, where the company's teaching artists have brought together Kurds, Shia, Sunni and Christians. They've had workshops with mixed groups of Israelis and Palestinians. As Hollander says: "You can't dance with someone you distrust."

Others also have used cultural diplomacy to help sort out conflict. In 1999, Daniel Barenboim and the late Edward Said founded their West-Eastern Divan Orchestra, bringing together young Israelis and Palestinians and other Arabs.

In an email, Mustafa acknowledged that he had not touched his violin in months, "too busy about ISIS. Bad people don't want to listen to music. No energy to play. We have a bad situation in my country as every one in the world knows about the war in Iraq but it isn't my reason because I don't count myself an Iraqi person, I am Kurdish and I live in Kurdistan which is a free region in Iraq. I like you teach me on Skype and I have computer in my room."

Erbil had never been on my radar, but I suddenly found myself reading everything I could about the capital of Kurdistan; like the rest of the world, I was also glued to the news there. Steve Coll in the New Yorker writes that since the American invasion of Iraq, this region "has been the most stable place in an unstable country."

It was impossible to put out of my mind that not far from this room where my student worked to improve his tone and acquire more technique, thousands of Yazidis had taken refuge on a desert mountaintop as they tried to escape Islamic State. On Aug. 18, two days before our first lesson, the Americans had come back into Iraq, after a two-year absence, to launch airstrikes in an effort to help the Kurds and Iraqis take back the dam near Mosul, as well as to protect American oil interests.

"I crazy about this!" he shouted.

At the end of the lesson, he said: "It's amazing time, really. You give me your time. Thank you so much."

"See you next week."

"Inshallah."

A week later, I wondered whether Mustafa would turn up for his lesson. In a way, he was like any other transfer student, in that I had to figure out what he needed most and in what order. On the other hand, he was in a crazy situation, on the outskirts of a very undefined, unconventional war zone.

It was Aug. 27, 9 a.m. in California, and there he was, right on the dot. We picked up where we had left off.

"Are you sure it's OK to take violin lessons with an American?" I asked.

"I have good place for security," he assured me.

"Can you help me technique to speed my finger?" he asked.

"Make an umbrella with your fingers," I told him, as I turned my upper body so he could see my straight forearm and left hand fingers over the fingerboard. He shot me a look.

"If you want to be able to move your fingers quickly..." I said, moving my fingers rapidly to prove my point.

He straightened his wrist, repeated the exercise and looked at his fingers in amazement.

I wanted him to have an etude book, and I held the book close to the computer screen so he could see the title. He disappeared, then reappeared, grinning, and gave me the thumbs-up sign as he held an ancient copy of the same music, Wohlfahrt written in big letters, with Kurdish letters above.

My next student was about to arrive.

"Listen, about pop music…"

"It's OK. I like classical music…," he brushed me off. He had listened to the Vivaldi "Seasons." "I crazy about this Vivaldi — good producer."

"Composer?"

"Composer," he said, making a mental note of it.

On the spur of the moment, I played "Over the Rainbow." He practically started dancing, he was so happy.

"I crazy about this" he said, beaming.

So I could teach him about pop music — from the last century.

My next student, an 11-year-old boy, and his mother walked in. I introduced them on Skype. Mustafa was thrilled to meet a student of mine in Los Angeles. "That's just amazing," my student's mother said as she wiped a tear from under her sunglasses. I explained to her son that this violin student was in northern Iraq. He shrugged.

It was hard to get Mustafa out of my mind. As a violin teacher, I am used to students graduating or moving on for one reason or another. Some stay in touch, some are never heard from again. No one's life was ever in danger, as far as I knew. Anything could happen to Mustafa, and who would tell the violin teacher 7,000 miles away?

As a violin teacher, I'd never thought at the end of a lesson that I might not see a student again.

At his third lesson, on Sept. 3, Mustafa told me that he was prepared to join the Peshmerga (armed Kurdish fighters). While military service in Kurdistan is voluntary and he'd never served, he said: "I can go to fighting. They not conquer my country."

Mustafa asked me if I'd heard about the journalist (James Foley) from the United States who had recently been beheaded. I nodded.

"I cried about this," he told me. He looked as if he were going to break down again.

"Let me hear your etude," I said, changing the subject.

A week or so later, Hollander emailed me. "Have you seen Mustafa's latest Facebook photos?"

There he was in military fatigues and boots, surrounded by other recruits, draped in the flag of Kurdistan, the violin nowhere to be seen. He canceled his fourth lesson. "Very busy," he emailed.