“Redeeming Eve” is worth examining, however, if only because it is the most recent of many attempts to capitalize on Austen’s continuing appeal. The half-dozen films of recent years are only high-profile versions of a quieter literary Austen-mania. Not only do both of Helen Fielding’s bestselling “Bridget Jones” books steal plotlines (one from “Pride and Prejudice,” the other from “Persuasion”), but noted fantasy writer Joan Aiken has written “Jane Fairfax,” “Emma Watson” and “Mansfield Revisited” — all sequels to Austen’s originals. Stephanie Barron has made Austen a sleuth, penning five mysteries with the author as the heroine, and Julia Barrett has written two sequels, “Presumption: An Entertainment” (to “P&P”) and “The Third Sister” (to “S&S”).

This summer, Barrett steps even more boldly into the footsteps of genius by completing Austen’s last work of fiction, the never-finished “Sanditon.” Though her book is a massive failure as well, it too illustrates the modern passion for Austen — and how fundamentally even the most ardent fans can misunderstand her.

Bokat’s heroine says that Austen’s novels “are the perfect wish fulfillment fantasy.” That is, they offer the romantics among us the thrill of seeing stoic heroes like Mr. Darcy and Captain Wentworth converted into ardent masses of jelly. The secret of Austen’s staying power is her precise modulation of character identification: In all of her novels a single female personality suffers agonies of misunderstanding with the almost unreachable hero, and yet Austen’s omniscient narrator inevitably gives us a few brief peeks into the mind of the desired object.

For example, in Mr. Darcy’s breast “there was a tolerable powerful feeling towards [Elizabeth], which soon procured her pardon, and directed all his anger against another.” And in “Northanger Abbey,” Henry Tilney finds Catherine Morland’s lack of education charming: “She was heartily ashamed of her ignorance — a misplaced shame,” the narrator informs us. “Where people wish to attach, they should always be ignorant. To come with a well informed mind, is to come with an inability of administering to the vanity of others, which a sensible person would always wish to avoid.” Catherine agrees with everything Henry says so earnestly “that he [becomes] perfectly satisfied of her having a great deal of natural taste.”

Austen’s brief excursion into the man’s point of view hints that the happy ending we demand is forthcoming, teasing us with it so we turn the pages all the faster. It assures us of the softening of the hero’s heart. It’s a formula, it works beautifully and it is indeed part of the novels’ enduring charm. But right before her death, Austen started off in a new direction, apparently breaking with the romantic paradigm. She began composition of “Sanditon” in January 1817. In July of that year, she died of Addison’s disease, and the subject of health is her explicit topic in the unfinished novel, less a love story or a novel of manners than an investigation of the economic and medical issues at stake in the oceanside developments that offered the “sea cure” to 19th century invalids.

Reading Barrett’s completion of “Sanditon,” titled “Charlotte,” the Austen fan feels disoriented. There is no indication in the new book of where Austen’s text ends and Barrett’s begins; nor does the short explanatory note tell whether Barrett has trifled with Austen’s prose at all or left it intact. Therefore, every sentence is suspect. Is it the work of a literary genius or a hack imitator?

For example, Austen’s previous descriptions of her heroines are absolutely precise, full of affection and criticism simultaneously: “No one who had ever seen Catherine Morland in her infancy would have supposed her born to be an heroine,” she wrote in “Northanger Abbey.” “Her situation in life, the character of her father and mother, her own person and disposition, were all equally against her.” Here, readers see Catherine’s fantasy life juxtaposed with her own ordinariness and can sense her buried frustration, her youth and her naiveti. What, then, are we to make of the following description: “Their invitation was to Miss Charlotte Heywood, a very pleasing young woman of two and twenty, the eldest of the daughters at home, and the one who under her mother’s directions had been particularly useful and obliging to them”? Too simple, too bland, too neutral to ever be Austen!

But it is. Minimal research proves “Charlotte” faithful to Austen’s text until Page 74, when Barrett’s begins. One reason it is hard to tell the difference is that the first third of “Sanditon” is not the Jane Austen we know and love: It is something more ambitious in its social scope. Charlotte, the ostensible protagonist, doesn’t appear until the end of Chapter 2, and the narrative is concerned with none of the exquisite social embarrassment Austen’s heroines so often suffer. Instead it deals with the emerging hierarchies of a community that is just forming itself in a newly booming town, and with the folly of hypochondria. It is harder to articulate why Barrett fails, because Austen was trying something new.

I shall try, however. Following Austen’s lead, but certainly in a most misguided manner, Barrett diverges wildly from the romance novel formula. She gives us at least eight different personalities to identify with, characters in bathing suits (!!) and a plot involving spice smuggling and some lowlife types down by the shore. The minute feminine dramas of the drawing room are abandoned for manly concerns of commerce. There is no impediment, either, to Charlotte’s marrying the designated hero, Sydney Parker. Indeed, he must simply overcome his rather apathetic nature and her heart is his. He loves her. She loves him. There’s no problem whatsoever — so who cares?

In addition to their other failings, neither Bennett nor Bokat provides anything like Austen’s scathing social critique. They do deliver the happy ending that seems to symbolize Austen to some readers. But mass market romance novels abound — they’re a dollar a dozen at any used-book store. People continue to read Austen in particular not just because she delivers the wish fulfillment fantasy but because she delivers it in a package that subverts many of its qualities. She is knowing, scathing, even caustic.

Smart readers can suck up the jelly of Mr. Darcy’s love without failing to note that Elizabeth dates her affection for him back to the moment when she first visited the enormous grounds of his beautiful house, Pemberley. We can drink in Henry Tilney’s fondness for Catherine and still congratulate ourselves on our worldliness, for the narrator reminds us that “though to the larger and more trifling part of the [male] sex, imbecility in females is a great enhancement of their personal charms, there is a portion of them too reasonable and too well informed themselves, to desire anything more in woman than ignorance.”

Modern readers are, I think, starved for this precise combination of satisfying romance and socially astute wit. The bitterness of the latter allows us to guiltlessly enjoy the honey of the former, which would choke us if swallowed pure. Austen’s enduring appeal is not costume-drama elegance, and it is not romance alone. It is woman-centered comedy that criticizes the follies of humanity.

Our most observant female novelists hardly ever attempt humor. Possibly because they’re still fighting for respect in a world populated by the Big Male Novelists Who Get Taught in Graduate School, they concentrate on serious topics like slavery (Toni Morrison), philosophy (Iris Murdoch), apartheid (Nadine Gordimer) or the darkness of the human soul (Joyce Carol Oates). And readers like me continue to make bestsellers out of lackluster romantic comedies by authors like Melissa Bank, Carrie Fisher and Laura Zigman. We buy books with heroines who name their cats Mr. Knightly, and slap down cash for feeble sequels by Austen imitators. We are desperate for that female voice raised loud in irritation, ironic and teasing, but still full of hope for the lovelorn. No one but blunderers like Bokat and Barrett even tries.

Jane Austen gave us that voice, that critique and that happy ending, too. It is a truth universally acknowledged. And we will love her forever for it.