This odd posture of contemplation made me ask for permission to sit beside him, and he gestured a welcome. He had dark hair and a neatly trimmed beard. He wore a black suit and looked vaguely Italian. He may have been 40.

I pulled out my own book, and he politely asked what I was reading. It was The Autobiography of Malcolm X. He asked what I thought of it, and, before long, we were wrapped in fervent conversation about war, injustice, and civil rights.

He had just come from a visit to New York City, he said, and it pained him to see the conflicts here between Jews and blacks. "If there were ever people who should identify and sympathize with each other, it is the Jews and the blacks," he said. "Their suffering as a people, their longing for justice -- they should see each other as allies."

We talked of the continuing agony of the war in Vietnam. He had a warm and expressive face, and when he shook his head and closed his eyes, he revealed deep pain and regret.

This conversation carried us halfway to the City of Brotherly Love and cocooned us from the crowded and noisy car. Our intimacy was interrupted by a man who stumbled from the first seat down the aisle toward the middle of the car, where we were sitting.

The man had the look of a person affluent New Yorkers work hard to avoid. He was old, ragged but not dirty, and with only a tooth or so left in his head. I avoided eye contact and turned back to my neighbor, but sensed his approach.

He muttered something I chose not to understand.

"Sorry, I don't smoke," I said, and waved him off.

I figured he was bumming a cigarette.

He returned a look somewhere between pity and disgust. "No," he said quite clearly now. "I'd like to borrow a pen." I was embarrassed. He needed a pen and had identified me as a student, a likely candidate to have one. I told him I didn't have one, but I could see he didn't believe me.

"Here." My neighbor had pulled a pen from inside his suit jacket. "Take this. In fact, you can have it."

The old man looked at the pen and then at my neighbor with surprise. It was an elegant Cross pen, and so the man scribbled something on a tiny piece of paper and quickly offered to return it.

"Please, go ahead and keep it. In case you need it again."

The old man looked hard into my neighbor's eyes, trying to read his motives. What he found there, I don't know, but he nodded and waved in appreciation.

"I thought he wanted a cigarette," I explained, regret burning on my face. "I don't smoke."

This photo was taken in a little apartment in Knickerbocker Village on the Lower East Side of New York City. Though Grandma Sadie was Jewish, she spoke Italian fluently and became the matriarch of a Catholic family that included 37 first cousins within a single city block. She served them as cook, counselor, psychiatrist, midwife, bail bondsman, and teacher. Her lap was one of the world's most comfortable places and, I think, the spot where I gained my first experience of music and literature.

His look turned to deep sadness when I told him how my mother, who is Catholic, was once spat upon after Sunday Mass by a woman who called her "that Jew," because her mother was Jewish. I wondered aloud what would have become of my grandmother during the Holocaust had her family not come to America.

We approached Philadelphia and would have only a few more moments together. He showed me the book he had just bought and had looked forward to reading. It was Legends of Our Time by Elie Wiesel, who had lost his family in the Holocaust, but who had survived the horror of the Nazi concentration camps. He had written books about his experience so no one could ever forget the effects of hatred, cruelty, and inhumanity.

The man held the book up and examined it.

"Here," he said. "Please take it. As my gift."

"I can't," I said. "You've looked forward to reading it." But he insisted, and I accepted. "What's your name?" I asked him.

He told me, but I've forgotten it. Then, he placed a dark fedora on his head. "You've probably guessed by now. I'm a rabbi."

"I thought you were Italian," I said lamely.

He said he had a congregation outside Philadelphia in a suburb called -- I don't remember, but I think it began with the letter "H." Haverford, perhaps.

"Look me up if you're ever in town," he said, and then he turned and walked off the train and into the crowds of 30th St. Station.

I looked forward to reading the book as a way of thanking the rabbi for his generosity. But I laid it aside, became preoccupied with my schoolwork, and then did the worst thing: I lost the book. I couldn't even remember the title or author.

I thought of the rabbi on the train many times in the years that followed. I knew that rabbi meant "teacher," and that he had taught me much during that 90-minute lesson on the train. But the story doesn't end there.

In 1990, I was visiting my family on Long Island. My mother and father were cleaning things out of the house and said I should go exploring through the attic and basement.

"Anything you don't want," my mother said, "we'll throw away or give away."

The search through closets and down hallways found me spelunking through a passage that was off-limits to us as children, the "crawl space." I removed a built-in bookcase, got down on my hands and knees and inched my way toward three cardboard boxes.

Two were insignificant, but the third was a treasure trove. For in that box were about 40 precious old books, some going back to my elementary school days. There, in the middle, in mint condition, was the book that had been lost for more than 20 years: the gift from the stranger on the train.