Vladimir Nabokov was once an invisible writer suffering from three of these unhappy conditions: the public, the private, the linguistic. As an émigré fleeing the Bolshevik upheavals, and later as a refugee from the Nazis, he escaped the 20th century’s two great tyrannies. And as an émigré writing in Russian in Berlin and Paris, he remained invisible to nearly all but his exiled compatriots. Only on his arrival in America did the marginalising term “émigré” begin to vanish, replaced first by citizen and ultimately by American writer – since it was in America that the invisible became invincible. But Brian Boyd, in his intimate yet panoramic biography, recounts the difficulties, even in welcoming America, of invisible ink’s turning visible – not only in the protracted struggle for the publication of Lolita, but in the most liberal of literary journals.

It was the otherwise audacious New Yorker of the 1950s that rejected a chapter of Pnin, the novel chronicling Nabokov’s helplessly charming and self-­parodying alter ego, “because”, according to Boyd, “Nabokov refused to remove references – all historically accurate – to the regime of Lenin and Stalin”. (The phrases in question included “medieval tortures in a Soviet jail”, “Bolshevik dictatorship” and “hopeless injustice,” characterisations which the editors apparently regarded either as excessive or as outright falsehoods.) Certainly the politically expelled chapter did not languish in invisibility for very long; and as for Lolita, decades after its electrifying and enduring triumph it burst out once again, dazzlingly, in the title of Azar Nafisi’s widely admired memoir linking Lolita’s fate to the ruthless mullahs of Teheran. (Still, even today, even in New York, one can find a distinguished liberal journal willing to make a political pariah of a writer: an instance of ordinarily visible ink rendered punitively invisible.)

And here at last is the crux: writers are hidden beings. You have never met one – or, if you should ever believe you are seeing a writer, or having an argument with a writer, or listening to a talk by a writer, then you can be sure it is all a mistake.

Inevitably, we are returned to Henry James, who long ago unriddled the conundrum of writers’ invisibility. In a story called “The Private Life”, Clare Vawdrey, a writer burdened by one of those peculiar Jamesian names (rhyming perhaps not accidentally with “tawdry”), is visible everywhere in every conceivable social situation. He is always available for a conversation or a stroll, always accessible, always pleasantly anecdotal, never remote or preoccupied. He has a light-minded bourgeois affability: “He talks, he circulates,” James’s narrator informs us, “he’s awfully popular, he flirts with you.” His work, as it happens, is the very opposite of his visible character: it is steeped in unalloyed greatness. One evening, while Vawdrey is loitering outdoors on a terrace, exchanging banalities with a companion, the narrator steals into Vawdrey’s room – only to discover him seated at his writing table in the dark, feverishly driving his pen. Since it is physically impossible for a material body to be in two places simultaneously, the narrator concludes that the social Vawdrey is a phantom, while the writer working in the dark is the real Vawdrey. “One is the genius,” he explains, “the other’s the bourgeois, and it’s only the bourgeois whom we personally know.”

And lest we dismiss this as merely another of James’s ghost stories, or simply as a comical parable, we had better recall that celebrated Jamesian credo, a declaration of private panic mixed with prayerful intuition, which so many writers secretly keep tacked over their desks: “We work in the dark – we do what we can – we give what we have. Our doubt is our passion, and our passion is our task.” The statement ends, memorably: “The rest is the madness of art.”

The madness of art? Maybe so. But more likely it is the logic of invisibility. James has it backwards. It’s not the social personality who is the ghost; it is the writer with shoulders bent over paper, the hazy simulacrum whom we will never personally know, the wraith who hides out in the dark while her palpable effigy walks abroad, talking and circulating and sometimes even flirting. Sightings of these ghost writers are rare and few and unreliable, but there is extant a small accumulation of paranormal glimpses which can guide us, at least a little, to a proper taxonomy. For instance: this blustering, arrogant, self-assured, muscularly disdainful writer who belittles and brushes you aside, what is he really? When illicitly spotted facing the lonely glow of his computer screen, he is no more than a frightened milquetoast paralysed by the prospect of having to begin a new sentence. And that apologetically obsequious, self-effacing, breathlessly diffident and deprecatory creature turns out, when in the trancelike grip of nocturnal ardour, to be a fiery furnace of unopposable authority and galloping certainty. Writers are what they genuinely are only when they are at work in the silent and instinctual cell of ghostly solitude, and never when they are out industriously chatting on the terrace.