Howard Jacobson: First the Mobot, then Kate Moss. It's like we snatched defeat from the jaws of victory

Remember Norman Hackforth, accompanist to Noël Coward and the "mystery voice" of Twenty Questions, the BBC radio quiz which kept the likes of me entertained from about the age of five until... well, I would say until the age of now if only the programme were still being broadcast.

It was Hackforth's job to whisper, as though from the cellarage, like the ghost of Hamlet's father, the word or object which the panellists had to guess. I thought of him the other day when I was listening to a more recent BBC radio programme, Amanda Vickery's History of Masculinity – a subject in which I retain some residual interest. Discussing Baldassare Castiglione's The Book of the Courtier, Professor Vickery introduced a word with which not every listener would have been familiar, and in my mind's ear I suddenly heard Norman Hackforth speaking it, as though it were a secret between him and the nation – "And the next word is sprezzatura".

The brilliant Anona Winn, with whom, aged five, I was in love, would of course have guessed it immediately. "Is it sprezzatura?" she'd have asked out of the blue, while Gilbert Harding was still sorting out the differences between animal, vegetable and mineral. Ah, the golden age of radio!

Forgive the nostalgia, but it is a proper accompaniment to my subject which is manly grace, the means of keeping or acquiring that quality which Castiglione calls sprezzatura, meaning nonchalance, not to be confused with spazzatura, meaning trash. Translate sprezzatura into "cool" and the astute reader won't need me to point out how much is lost. Musicality is part of it, the abundance of vowels suggesting all the time in the world, a certain measured stateliness of movement enjoyed for its own sake, free of ostentation or effort.

While "cool" thinks it's on a similar errand, in fact it evokes true effortlessness neither in the saying nor the performance. Cool is now, and probably always was, so mortgaged to style and showing-off that it defeats its own purpose, as witness, in ordinary life, the wearing of sunglasses when the sun don't shine and, in extraordinary life, the behaviour of those Olympian alpha males who went into the sporting equivalent of St Vitus' Dance whenever they saw a camera looking their way.

Make no mistake, Castiglione does not seek to promote soft manners at the expense of athleticism or bravery. "I am of opinion that the principal and true profession of the Courtier ought to be that of arms," he has his friend Ludovico da Canossa advise, "and to be known among others as bold and stern." But, while to be bold and stern in the face of the enemy is essential, let him "in every other place, [be] gentle, modest, reserved, above all things avoiding ostentation and that impudent self-praise by which men ever excite hatred and disgust in all who hear them".

It should surprise no one that Usain Bolt, a magnificent and still young athlete with an audience to please, a career to bolster and merchandise to sell, should play the braggart, fill his mouth with "impudent" hosannas to himself, steal the limelight from fellow gold medallists, and seek every opportunity to be photographed pulling faces and striking poses likely to delight, and then to be emulated by, pre-adolescent boys; but that grown men and women paid by the BBC to commentate on what they see should describe such mental commotion as "cool" only reminds one of how far the corporation has sunk, when it comes to vocabulary and discernment, since the days of Norman Hackforth and Anona Winn.

It was furthermore sad, I thought, to see Mo Farah, who more nearly approximates to Castiglione's ideal – bold but gentle, strong but modest – feeling he had to find some matching body-logo of his own to ensure notice. How much the more susceptible, then, will boys be who have no prowess yet to recommend them other than the powerful longing to proclaim their cool on Twitter?

Unburdened by any obligation to the neuroticism of macho, the women athletes, winners and losers, beat the men hands down (literally) in the matter of modesty and reserve. The most touchingly dignified moment of the 2012 Olympics for me came when Christine Ohuruogu shrugged off the banal consolations of her pestiferously upbeat interviewer, lowered her eyes, and admitted she was "heart-broken" to lose her title. Just that. Heart-broken. There was nothing more to say.

Victoria Pendleton, too, in trying circumstances – I'd have been screaming "Cheat!" in that sprint final myself – inclined her head to second best. She is reported as wanting to swap heroism for the glamour of Strictly Come Dancing. I'm sure she'd be lovely to watch, but may she change her mind.

Legacy, Victoria. Remember inspiring a generation. I know, I know, legacy went out of the window ere the funeral baked meats for the Games were cold, with a closing ceremony honouring the very culture of celebrity for celebrity's sake which everyone had hoped aloud the grandeur of the Games would for a while at least, if not once and for all, eclipse.

Here was true effort, we were saying; here was skill, absorption, endeavour, a dedication and seriousness that would surely show our sad, star-struck young the vacuity of the unearned fame they craved, winkle them out of their beds of daydreams, get them into kayaks or on to taekwondo mats, demonstrate not just the virtue of exercise but the pleasure, the joy, of commanding something other than the wandering attention of those entrepreneurs of spazzatura who grow fat on their fantasies.

And so what do we do? We wheel out Kate Moss, Naomi Campbell and Posh Spice. The languid, the petulant, the sulky. The antithesis of all we've marvelled at for a fortnight. And in a flash our memories of the pommel horse and the keirin (not that I can yet claim to understand the keirin) are trashed.