[The Independent, UK, 11 August 2001]: I once asked the head of the Lebanese Hizbollah if he could explain to me how the mind of a suicide bomber works. Sayed Hassan Nasrallah was dressed in his black turban and robes. He had formerly been the Hizbollah's military commander in southern Lebanon and from his legions had emerged the first Arab suicide bombers who would - after more than a decade and a half - sap the morale of Israel's retreating army. Explain to me as a Westerner, I told Nasrallah, how a man can immolate himself.

"Imagine you are in a sauna," Nasrallah replied. "It is very hot but you know that in the next room there is air conditioning, an armchair, classical music and a cocktail." There was a pause as the Hizbollah leader moved his hand swiftly upwards, as if opening a door. "So you pass easily into the next room." I will not forget the smile he then visited upon me. "That," he said, "is how I would explain the mind of the martyr to a Westerner."

Nasrallah enjoyed metaphors, similes; like the Hizbollah's "martyr" posters which so often show the dead in paradise, surrounded by rivers and tulips and weeping willows. Is that where the suicide bombers really believe they are going, I used to ask myself? To the rivers of honey and the trees and - yes, of course - the virgins?

The idea that sacrifice is a noble ideal - and let us, for a moment, put aside the iniquity of murdering children in a Jerusalem pizzeria - is common to western as well as eastern society. Our First World War calvaries in France are covered with commemorations to men who supposedly "laid down their lives" or "gave their lives" for their country - even though most died in appalling agony, praying only that they would live.

When, years after our conversation, Nasrallah's own son was killed in a suicidal assault on an Israeli army position in southern Lebanon, the Hizbollah leader insisted that he receive not condolences but congratulations.

Nasrallah appeared on Lebanese television, laughing and smiling, beaming with delight as he spoke to wellwishers on the phone. His son's young fiancee also expressed her pride in her dead husband-to-be. But she did not smile.

If the idea of self-sacrifice is thus comprehensible, it is clearly not a natural phenomenon. In a normal society, in a community whose people feel they are treated equally and with justice, we regard suicide as a tragic aberration, a death produced - in the coroner's eloquent lexicon - when "the balance of the mind is disturbed". But what happens when the balance of a whole society's mind has been disturbed? Walking through the wreckage of the Sabra and Chatila Palestinian refugee camps in Beirut a few weeks ago - the same camps in which up to 2,000 civilians were massacred in 1982 and for which, on page 103 of its report, the Israeli Kahan Commission held Ariel Sharon "personally responsible" - I could only wonder at the stability of the survivors who still lived there amid the concrete huts and the garbage and the football-sized rats. If I lived here, I remember thinking, I would commit suicide.

And that, of course, is the point. When a society is dispossessed, when the injustices thrust upon it appear insoluble, when the "enemy" is all-powerful, when one's own people are bestialised as insects, cockroaches, "two-legged beasts", then the mind moves beyond reason. It becomes fascinated in two senses: with the idea of an afterlife and with the possibility that this belief will somehow provide a weapon of more than nuclear potential. When the United States was turning Beirut into a Nato base in 1983, Iranian Revolutionary Guards in Baalbek were promising that God would rid Lebanon of the American presence. I wrote at the time - perhaps being tongue-in-cheek - that this was likely to be a titanic battle: US technology versus God. Who would win? Then on 23 October, 1983, a lone suicide bomber drove a truckload of explosives into the US Marine compound at Beirut airport and killed 241 American servicemen in six seconds. I later interviewed one of the few surviving marines to have seen the bomber. "All I can remember," he told me, "is that the guy was smiling."

I spent months studying the suiciders of Lebanon. They were mostly single men, occasionally women, often the victims of Israeli torture or the relatives of family members who had been killed in battle with Israel. They would often receive their orders while at prayer in the "masjid" or mosque in their south Lebanese villages. The imam would be told to use a certain phrase in his sermon - a reference to roses or gardens or water or a kind of tree. The cleric would not understand the purpose of these words but in his congregation a young man would know that his day of "martyrdom" had now arrived.

In Gaza, even before the 1993 Oslo agreement, I discovered an almost identical phenomenon. As in Lebanon, the would-be "martyr" would spend his last night reading the Koran. He would never say goodbye to his parents. But he would embrace his mother and father and tell them not to cry if he were one day to die. Then he would set off to collect his explosives. Five minutes before he set off from the West Bank town of Tulkarem last week, a young Hamas member went through this very ritual. Five minutes later, an Israeli missile struck the car he was driving. But scarcely a week later - at two o'clock on Thursday afternoon - another suicider reached the doors of the pizzeria on the corner of Jaffa Street and King George's Street in West Jerusalem.

Yet there's a terrible difference with the suicide bombers of Palestine. However frightening, the Japanese 'kamikaze' pilots attacked battleships and aircraft carriers, not hospitals. The Lebanese largely followed this pattern: they usually went for military targets. I was puzzled why the Lebanese should have been queuing to watch Pearl Harbor when it opened in Beirut last month - until I saw the young men studying the cinema stills of equally young Japanese pilots tying their "martyrdom" bandannas around their foreheads. In similar fashion, the Hizbollah targeted the Israeli army and its militia allies. The Palestinians learned from all this.

But more and more, their suicide bombers have targeted Israeli civilians. A battleship or an Israeli tank is one thing; a three year-old waiting for his mother to cut his pizza for him is quite another.

I called a Palestinian friend yesterday morning to ask about this, to ask how young Palestinian men - in Lebanon as well as Ramallah - could rejoice in the streets at the pizzeria massacre. She expressed her abhorrence at what happened - she was genuine in this - but tried to explain that the Palestinians had suffered so many civilian casualties since the "intifada" began that Palestinians found joy in any suffering inflicted on their enemy. There was a feeling that "they should suffer too"; which, of course - and the principle applies, though not the historical parallel - is exactly how Air Marshal Sir Arthur Harris explained his area-bombing policy against German civilians.

But I go back to my own first reaction when I reached the Sbarro pizza house. Unforgivable. What did that eyeless, dead Israeli child ever do to the Palestinians? Could not the Palestinian bomber, in his last moments on earth, recognise this child as his daughter, his baby sister, his youngest cousin? Alas, no. He was too far down the road to his own death, too buried in his own people's tragedy. His was not an act of "mindless terror", the words Israeli spokesmen use. He was the logical product of a people who have been crushed, dispossessed, tortured and killed in terrible numbers. The pressure cooker of the West Bank was his sauna. And he passed through the door.