IT'S DIFFICULT, even a century after her literary career began its decline, to talk about Marie Corelli without succumbing to a battery of adjectives. Often condemned as a hack and praised as a saint, Corelli was something altogether more interesting, a sort of Oscar Wilde in reverse. If Wilde’s lampoons show a certain tenderness toward human hypocrisy, the joke being that most everyone is terrible, Corelli’s satire, while no less affectionate, sides always with the angels. Hers is a sincere sarcasm. She was a flamboyant puritan, an antisuffragist cryptofeminist, and a defender of traditional morals who lived all her life with another woman. On a wall above the mantel in one of the main halls of Mason Croft, the house she shared with her lifelong companion Bertha Vyver, both women’s initials appear encircled by a wreath. The caption underneath reads “Amor Vincit.” (All-conquering love notwithstanding, it’s likely that Corelli’s relationship with Vyver remained platonic.)

Corelli ought to be well remembered as a late 19th-century publishing phenom alone: her book sales exceeded those of contemporaries H.G. Wells, Sir Arthur Conan Doyle, and Rudyard Kipling combined. Derided by critics and even her own biographers for being too sensational, and later by the public for writing herself into her own work like a kind of fin de siècle Mary Sue, Corelli’s real gift lay in combining exotic high fantasy themes with the prosaic cynicism of London society without quite capitulating to the formulae of either. She could even be called a cult leader of sorts: her first novel, a first-person narrative titled A Romance of Two Worlds, introduced something called the Electric Principle of Christianity, a well-theorized fictional religion that caught on like wildfire. Sales of the novel soared and the Electric Principle developed a dedicated following.

It’s difficult to reconcile Corelli’s current near-total obscurity with her once vast literary footprint. Loyal readers named their children after her. Pages of her novels were found in the Boer trenches. Her fan base began with the eccentrics at society’s lower end and went all the way up to Queen Victoria. Corelli was the monarch’s favorite author, and if you think about it this makes perfect sense: her books are high flown, aspirational, unsubtle, workmanlike, idealistic, rich in pseudo-Shakespearean ruminations, pleasurable in an instructive way, siding with the virtuous but fully understanding — and reveling in — the value of a good villain: perfect bedtime reading for English queens. (If the genre of “high fantasy” takes place not in this world but in a richly-rendered imaginary universe, what more perfectly represents it than Queen Victoria, who politely owned and governed half a world she never even saw?)

Conventional wisdom says there’s nothing surprising about Corelli’s fall from favor; it’s the bestseller’s fate to be forgotten, and the price of popularity is oblivion. But Corelli’s work has left significant literary traces: besides t...