Howard Jacobson: I'm tired of this tragedy and want to return to the comic coinage of life again

You can tell that things are getting back to normal when you are once again able to sit around with your friends discussing blow jobs and everyone understands you mean fellatio not terrorism. I make that sound more gratuitous than it was. In fact, we were sitting round discussing a particular blow job, or, to be precise, the artistic viability of a particular blow job – the one that doesn't quite eventuate (I'm going to say no more than that, for fear of giving away the story) in the Coen brothers' latest film, The Man Who Wasn't There.

You can tell that things are getting back to normal when you are once again able to sit around with your friends discussing blow jobs and everyone understands you mean fellatio not terrorism. I make that sound more gratuitous than it was. In fact, we were sitting round discussing a particular blow job, or, to be precise, the artistic viability of a particular blow job – the one that doesn't quite eventuate (I'm going to say no more than that, for fear of giving away the story) in the Coen brothers' latest film, The Man Who Wasn't There.

What we were discussing was whether, at the time of the film's action – 1949 – a woman of that age, class and education would have known what a blow job was, let alone had the temerity to offer one. Mine is not an historically illiterate circle. We are aware that the Phoenicians were exporting blow jobs around the eastern Mediterranean three thousand years ago. We know that what launched the Greek fleet Troywards was almost certainly Helen giving more head to Paris than she ever had to Menelaus, and that Judith's beheading of Holofernes was her very pointed way of saying no to the Assyrian general's proposals.

Nor do we fall into the common error of associating Lesbos with female homoeroticism, the truth being that the verb lesbiazo actually refers to fellatio, of which the citizens of Lesbos were devotees. But the antiquity of the blow job was not the point at issue. What we could not agree about was whether, by 1949, an American college girl had yet come out of that new dark age imposed by American puritanism.

The book you go to to settle arguments of this sort is Cate Haste's Rules of Desire, a social history of sex from the First World War to the present day. A history of specifically British sex, I grant you, but, given how sex travels, still not without its transatlantic bearings. According to Cate Haste, Theodore van de Velde's Ideal Marriage, which was translated from the Dutch and published in England and America in 1930, authorised the "genital kiss" as part of acceptable love play and sold nearly a million copies.

That clinched it for me. There might have been some moral backsliding in America between 1930 and 1949, but not enough to have wiped the blow job from popular awareness altogether. The Coen brothers were right. And one of the bleakest scenes in cinema survives the charge of anachronism.

It was five or six days ago we sorted that out, and I have been feeling guilty since. You know the process: the simple pleasures of exchanging the comic coinage of life again, followed by remorse for forgetting to be tragic. What do I need to keep me mindful – another atrocity? A cold quicksilver sweat comes over me when I think I might crave the exhilarating jolt of more terror. Can that happen? Can we get a taste for it, not out of callousness but some perverse refinement of its opposites – horror, reprobation, conscience and, who knows, maybe even ghoulishness. Is it possible to become an addict of horror, a disaster junky, forever upping the dose in order to go on satisfying that sense of outrage one's conscience demands?

"Never forget", we engrave on Holocaust memorials. But without fresh instances of horror we do forget, and what is more we know we should forget, for it is morbid not to, an obstinate condolement, unmanly grief. It can also be argued that mourning never becomes the dead more than when it's over, that we best remember those we would like to see again when we forget to remember that we can't.

Think of it as loving forgetfulness, a happy oblivion of the sort Wordsworth expressed with such a rush of poignancy – "Surprised by joy – impatient as the Wind/ I turned to share the transport – Oh! with whom/ But Thee, deep buried in the silent tomb." – followed by the agonised minutiae of self-reproach: "But how could I forget thee? Through what power,/ Even for the least division of an hour,/Have I been so beguiled as to be blind,/ To my most grievous loss!"

Excruciating, that "least division of an hour", allowing the crime of inattention no hiding place, not even in the smallest fold of time. So, too, "beguilement", with all its diversions and delusions, including the cruelest and kindest delusion of them all: that the dead are not dead.

So you sit around ascribing dates to blow jobs when actually what you should be doing is... What? Moping? Mobilising? Don't ask me. I simply note the reservoir of trivia filling up again, day by day more flotsam on the scummy surface of our beleaguered values. Gwyneth Paltrow in a row with Harper's Bazaar because it has shown a photograph of her bottom, her whole bottom, when the deal, she says, was for half a bottom only. Harry Potter, the only character in literature known to any person under 35. Civilisation? Did someone mention civilisation?

I know the arguments. Not for Gwyneth Paltrow's bottom, but for Harry Potter. Suddenly, thanks to Harry Potter, kids who have never read a book before are devouring them by the truck load. Today it's Harry Potter, tomorrow Daniel Deronda. Rubbish. I've done the science. I've tailed kids who've just finished Harry Potter and not one of them goes into Books Etc to buy Daniel Deronda. They just buy another Harry Potter.

Surprised by joy, impatient as the wind, I turn to share the Harry Potter. Beats being serious, and, some would no doubt say, beats talking about blow jobs. But I dispute that.