'The crux of the matter," said Hilary Mantel in her brilliant speech at the British Museum this week, is that "a royal lady is a royal vagina". She was right. It's not usually put so bluntly of course, but the royal family, more than any other, centres on lineage - on fertility, thwarted dreams, carefully nurtured heirs and heavily scrutinised wombs. Princesses have existed under crushing pressure to produce boys who will sow the blue blood lines that thread today's polite monarchs to the titans and tyrants of the past.
This is why, when queens gave birth centuries ago, prime ministers, chancellors and archbishops used to sit in an adjoining room - a horrendous prospect for any mother - craning ears and boasting of glimpses: they were there to verify a monarch's child had been born.
"Royal persons are both gods and beasts," Mantel said. "They are persons but they are supra-personal, carriers of a blood line: at the most basic, they are breeding stock, collections of organs."
The Duchess of Cambridge knows this well: the prurient excitement about her swelling belly has become hysterical and her pregnancy has been heralded as a matter of global importance.
Mantel's shrewd, original insights, given at the behest of the London Review of Books, were the best I have read about the treatment of women in the royal family for a very long time. The vicious attacks that followed were ludicrous.
In her analysis, Mantel compared Marie Antoinette and Princess Diana, two other royal consorts who had been "gliding, smiling disaster[s]", to the duchess, who was instead almost eerily perfect for her role - so perfect it seemed as though she had been crafted, or spun. She "appeared to have been designed by a committee and built by craftsmen, with a perfect plastic smile and the spindles of her limbs hand-turned and gloss-varnished". She was "irreproachable: as painfully thin as anyone could wish, without quirks, without oddities … She appears precision-made, machine-made." All of which is true.
There was a danger in such a prominent, apparently flawless woman becoming, Mantel said, "a jointed doll on which certain rags are hung". At first, she was seen as a mannequin simply defined by her clothes, and soon she will be a mother whose "only point and purpose" is to give birth.
For these remarks, Mantel was howled down, spat at, and accused of being a jealous, barren, over-medicated and ugly old lady. Even the British Prime Minister, David Cameron, chastised her for remarks he wrongly believed to be disparaging of the Duchess of Cambridge.
The frenzy at the suggestion that an older, plainer woman could possibly interrogate the life of Prince William's immaculate wife was so manic that at first it drowned out the substance of her speech.
But this tornado of tabloid rage - and the response to it - demonstrated three things. First, we must ask more authors such as Mantel to make speeches that slice through banality and make us think. How glorious it was to read her elegant prose in the middle of a news cycle spotted with ugly phrases like "ruling it out" and "at the end of the day".
Second, a strangely sexist faux chivalry makes people turn on anyone who dares criticise a beautiful young royal, especially a pregnant one: the implication behind the slamming of Mantel as a crone with buck teeth was that only women who are beautiful can comment on other beautiful women. Must the imperfect - the vast bulk of us - remain silent? Surely I am not the only person to believe it is absurd to be discussing the physical attributes of Mantel, a stunningly talented two-time winner of the Booker Prize. It was not just preposterous but unfair: although news sites dug up and splashed the most unflattering photos of her alongside the duchess, Mantel has a striking poetic beauty; with her pale skin and large blue eyes under arched brows, she looks like a Vermeer painting.
Third: an instant leap in Mantel's book sales shows that sometimes, despite the shrill trilling and nastiness of tabloids such as the Daily Mail, the cerebral really can triumph. After her brief excoriation, people who are literate, curious and had actually read the speech rose to vigorously defend her. Before long, these voices were the loudest: a chorus of common sense. This was a victory of sorts.
The initial response to Mantel's musings on how brutish and shallow our view of royals can be only underlined her point.
The initial response to Mantel's musings on how brutish and shallow our view of royals can be only underlined her point. We gawp at them for being extraordinary, while empathising with them for being ordinary; mortals who fall in love, give birth, battle with wayward teenagers, grow old and grieve. But while we watch, relate to them or ignore them, we begin to see them as our own.
According to G.K. Chesterton: "the degree to which the middle and lower classes took Queen Victoria's troubles and problems to their hearts was almost grotesque in its familiarity."
This is what Mantel was addressing: when does this familiarity become grotesque? When does persistent curiosity become contempt? Who owns the Duchess of Cambridge's body?
Kate Middleton knows her fate, and appears to have stared it in the eye and made a pact, like the Little Mermaid who promised to swallow her voice so she could walk on land and marry her prince. Her body though, has already been stretched by the rack of public inquiry to what must be at times an unbearable extent, despite her public composure. We are all acquainted with her breasts, bikinis, and bumps, thanks to editors who pay richly for snaps of her bare skin.
This week, Mantel asked us to "back off and not be brutes". If her words have prompted us to ponder the hell we can put women in the public eye through - and encouraged more literary types to enter the fray of public opinion - it will have been worth riling Cameron. I hope Mantel stares down critics with the same intensity with which she confessed she stares at the Queen.
Julia Baird is writing a biography of Queen Victoria.