Among the many vices that have flourished in the internet age, vengeance must rank second only to lust. Not so long ago, it was only Sicilians and tribal warlords who settled their own scores. The rest of us were supposed to rise above it, or phone a lawyer. Taking matters into your own hands was considered undignified, uncivilised and, above all, self-defeating. "Therein lies the defect of revenge," grumbled Mark Twain. "It's all in the anticipation; the thing itself is a pain, not a pleasure."
Would Twain have felt differently with the world wide web at his disposal? These days, there are a million easy, spectacular and - crucially - anonymous ways to punish those who do us wrong. Caught your lover cheating? Just post a naked photograph of him on urdumped.comand wait for the invective to pour in. Too busy to exact retribution yourself? Just sign up with payback.com, and they'll send anonymous emails and letters of abuse for you. ("Whether it is an annoying co-worker, a backstabbing friend, or that person with the horrible bad breath that never stops babbling away, we have you covered," promises the company blurb.)
And then there's the entirely bespoke approach - as experienced by Amir Tofangsazan. Several months ago, this A-level student from Barnet, north London, sold his old laptop on eBay for £375. Unfortunately, the buyer, a computer buff, was not happy with his purchase: he claims it arrived two months late and didn't work. Instead of grumbling impotently to himself, he decided to get even. He fixed the machine, opened up the hard drive and pulled out all sorts of incriminating items that Amir had left behind.
Then he posted them all on a web page, in Amir's name, entitled The Broken Laptop I Sold on eBay. The page opens with the words: "Hello. My name is Amir Massoud Tofangsazan. I'm 19 but pretend to be a lot older and like to pretend that I'm a big businessman when I'm actually not that clever." After that, the gloves come off.
There are photographs of Amir seductively baring his chest for the camera, kissing a girl and snoring open-mouthed on a sofa. There are dozens of pictures of women's legs - apparently taken on the London Underground with a camera phone - as well as downloaded images of foot fetishism and middle-aged women bending over in complicated underwear.
Equally painful to behold are the extracts from Amir's CV - "Football which I used to play in my secondary school which I was the nominated captain due to my leadership and communication skills (sic). My interests include cooking the stock market (sic)" - and a description of himself apparently written for a dating website: "I am an exciting fun guy who loves to have fun and outgoing times. I find myself to be very honest on all occasions. Basically I am a very chilled guy and I always put the lady the first (sic)."
As a final flourish, the anonymous buyer emailed everyone in Amir's address book to alert them to the web page, thus sparking off a viral phenomenon. The site has received almost half a million hits. It seems the whole world is laughing at Amir's downfall - with one or two notable exceptions.
"I am shaking all over and I fear my reputation is going to be ruined," the teenager himself said this week. "My father is very angry." Iranian-born Mohammad Tofangsazan certainly does seem displeased. "It is very distressing for the family," he said. "I don't think Amir will be coming back here for some time."
But sympathy for Amir is scarce, at least in cyberspace. Nobody loves an eBay cheat - even one whose guilt has yet to be proven - and there is widespread jubilation at the manner of his comeuppance. In some chatrooms, the righteous indignation tips over intoincandescent fury, much of it racist. "Typical ARAB always trying to rip someone off," thunders one visitor. "I bet his buddies in al-Qa'ida will never let him live this one down," opines another.
In a curious way, though, the ugliest sentiments are not the most shocking. It is no great surprise to discover racist thugs enjoying another person's discomfort; much more alarming, surely, to find respectable IT nerds and eBay addicts looking on in satisfaction. In the lawless world of the internet, natural justice prevails: even gentle, well-meaning people can find themselves swept up in the mob, immune to doubt or empathy.
Yet Amir's fate could be yours or mine tomorrow. Very few of us get through life without enraging someone. Anyone with a modicum of determination and know-how could find your personal details on the internet, and make mischief with them. It has never been easier to throw mud at people, or harder to slough it off.
The trouble with vengeance is the same as it has always been: it titillates the nastiest parts of human nature, fractures the bonds of kindness that hold society together, and supplants the rule of law with mob rule. The pleasure is temporary: the pain, as Mark Twain realised, is subtle but lasting.