Waiting in line at a West Bank border checkpoint, intimidated by the prisonlike atmosphere and frustrated by the Israeli soldier denying me passage back into Israel, I got my first real taste of what it's like most days for thousands of Palestinians. There I was, having just enjoyed visits to several Palestinian towns, looking very much the harmless, middle-class American tourist, with what I was sure were the right stamps in my passport, being told I could not re-enter Israel nor continue my trip to Nazareth.

I gave the young soldier my best surely-you-don't-mean-me look. Then, a polite request to "please call a superior officer." All to no avail. I would have to return to "wherever I came from."

This was my second trip to Israel and the occupied Palestinian territories. I had wandered all over Jerusalem, spent a day at Yad Vashem, the Holocaust museum, talked with young people at the Aida refugee camp and walked the battle-scarred market in Hebron. I had been treated to full-gauge Middle Eastern hospitality at friends' homes in Jifna and Jerusalem.

I was on a distinctly personal mission. For four years I had been working on a project that others devote their lives to: trying to understand the endless conflict that grips Israelis and Palestinians and causes such suffering to both.

My mission was born reading of the 2003 death of David Applebaum, an innovative Israeli emergency room physician who along with his daughter was killed by a suicide bomber the night before the young woman's wedding. It has been reinforced many times since, in part by stories of Palestinians killed or imprisoned or those who simply endure daily humiliation at Israeli checkpoints.

On this trip I was trying to understand a life under occupation.

For a caretaker at a Jerusalem nursing home, it meant that a daily trip that should take half an hour instead takes two to three hours. For a Palestinian father of five, a Jewish holiday meant "closure" of the border and the threat of a lost job when he could not get to Jerusalem for work. For a man in his 60s from Zababdeh whose identity papers would not allow him to travel to Ramallah for the heart surgery he needed, occupation meant "borrowing" his cousin's identity papers to gain passage through a crucial checkpoint.

After I visited Palestinian Christian families in Zababdeh, an Anglican priest friend, Fadi Diab, drove me to the checkpoint at Jalameh, a massive facility of steel and barbed wire designed to deter the kinds of militant attacks that have killed scores of Israelis and Palestinians at various checkpoints. We got there at 5 p.m., when the checkpoint was to open for two hours, and joined the 15 to 20 Palestinians patiently waiting at the gate. While we were waiting, a man, obviously not Palestinian, approached Fadi and me, introduced himself as Harry and told Fadi he would see that I made it through all right. My anxiety was apparently showing.

When Jalameh opened 45 minutes later, I successfully passed a cursory inspection by Israeli guards, moved through a first turnstile and was herded with Harry and the others into a room no larger than 10 feet by 15 feet.

After 30 minutes of waiting, the women grew edgy and the children began fussing. The men seemed used to it. We moved then through an X-ray station to a room where we emptied out all our possessions for manual inspection.

I felt especially intimidated -- as I had during my last passage through Jalameh -- by soldiers patrolling the overhead metal walkway with M-16s. After nearly an hour we approached the final turnstile, and I was beginning to breathe more easily.

It was there that the soldier reviewing my passport told me I didn't have permission to leave the West Bank. And there that Harry swung into action, assuring me he would not leave until I was released.

Harry, I later learned, was an Israeli chiropractor from a kibbutz near Haifa. He traveled weekly to Jenin to treat Palestinian refugees, a fact that did not endear him to the Israeli guards. But for the better part of an hour, Harry argued with a small circle of soldiers and officers while I stood on one foot and then the other, trying to remember to breathe.

What amazed me was the calm with which Harry took to his task. At one point, after a tense exchange with the guard standing above us, he said, "I will not let you make me your enemy, and I will not allow you to become my enemy." A valuable lesson in peacemaking and effective negotiation.

Harry finally wore them down. I was released, and Harry drove me to Nazareth.

I don't yet understand how the Palestinian people endure the oppression of an occupation or what it feels like to be a Palestinian. I could always have returned to Zababdeh, called the American Consulate and gotten out.

An ordinary Palestinian would have no such advocate, or even, perhaps, an Israeli friend like Harry.