Boris Johnson says that the end of Yasser Arafat - the man who brought so much suffering to his own people - could be the opportunity for lasting peace But why did he do it? I asked the dark and bony young man in the yarmulka, still clearing up the scene of the murders. We were standing at the blackened steel counter of Shimmi's cheese and olive shop, where three people had yesterday been killed by a suicide bomber and 13 seriously injured. It is a testimony to the vibrancy of the Carmel market, Tel Aviv, that business had resumed at the neighbouring stalls within minutes of the detonation, as though an act of self-destruction and murder by a 16 year-old was as banal as a traffic accident. Shimmi's cheese shop still had ripped awnings and bust fluorescent lights, but fewer than 24 hours later the shop boy was getting ready to open again, and he didn't seem disposed to ponder on my question. 'I cannot imagine why anyone would do that,' he said. So I turned to Ran, my affable minder from the Israeli foreign office. Why did he do it? I repeated, looking at the sinister fatty globules still adhering to the counter. A Jewish religious organisation called Zaka had been fossicking away for hours, in obedience to the code that says all body parts must be interred; but it was impossible not to speculate about the stains. Amar al-Far was just a kid, one of the youngest suicide bombers ever. What made him leave the Askar refugee camp near Nablus, pass through the Hawara checkpoint, and kill himself and three blameless Israelis, including Leah Levine, 67, a holocaust survivor? How could anyone persuade a child to do something like that? 'He was expecting the 72 Virgins,' said Ran, 'like you have written in your novel.' Flattering though this answer was, it didn't quite work, for me. Maybe it was true that Amar al-Far dimly expected to be cosseted in paradise by the 72 black-eyed ones of scripture, which some authorities say should be correctly identified with raisins rather than virgins. But was that hope really enough to encourage a sentient adolescent to come to a shop and blow himself into a compote of cheese, persimmons and human remains? No one seemed to have the answers in the Carmel market, least of all an old man who — so said that morning's Jerusalem Post - had stared at the mayhem and announced, 'It was the pork. It was the pork that brought on our doom.' He meant that the market was being punished for tolerating an outlet as exuberantly non-kosher as the Baboy butchers, two stalls down, which had a picture of a round, pink, beaming, curly-tailed porker, and the advertisement, 'Here we sell fresh pork.' A million Russian Jews have arrived in recent years, and their fondness for 'white steak' causes great offence. So I left Carmel market with two barmy opinions from the rival theologies: the killings were either inspired by the heavenly promise of 72 peach-bottomed girls, or else by heavenly anger at the consumption of pork; and, since neither seemed adequate, I wanted to go to Nablus, where the kid's parents were saying the most extraordinary things. The mother was sad, she said, that her child was dead, but the real pity of it was that he had died so young. They should have waited until he was older, she said, before turning him into a suicide bomber. And that was his mother! What kind of sick society is it, in these refugee camps, that a mother could condone the suicide, at any age, of her son? The trouble with going to Nablus was that it meant giving my nice Israeli handlers the slip, and when I reached the checkpoint I found that I couldn't get in. No way, said an Israeli soldier, unimpressed by all the credentials I could muster, including a new Israeli press pass. The town was closed for an 'operation'; by which it turned out he meant the search for the associates of the suicide bomber, and the customary destruction of his family home - intended to be a deterrent to other families. But as I looked at the Palestinians queuing to get into their own town, waiting to be passed by Israeli troops through the urine-soaked turnstiles, I had an inkling of the frustrations that might produce a cult of suicidal martyrdom. It wasn't the promise of 72 Virgins that drove a young, talented female lawyer to escape from the Occupied Territories to Haifa, a mixed Arab-Israeli town. I don't believe it was the notion of carnal bliss in heaven that made her order lunch in a crowded restaurant, pay for the meal, then stand by a baby's trolley (the suicide bomber manuals always recommend standing up, in buses or restaurants, for the decapitating effect) and blow herself up. It is all about a sense of powerlessness, and rage, and hatred, and a sense of injustice. And if you want to see the physical embodiment of that injustice, then you must go to the wall, or fence, as the Israelis prefer to call it. The wall/fence now runs for only 200km of its projected 700km, and as a security measure it must be rated a triumphant success. In its wall incarnation it is huge, much higher than the Berlin wall, grey and forbidding and covered with wire and watchtowers. But it is a wall only for very short stretches, and just as effective when it appears as an electronic fence, equipped with no anti-personnel devices whatever.