When E L James' erotic sensation Fifty Shades of Grey reached e-book best-seller status this spring, it ruffled more than just bedsheets. Moralists ranted. Literary critics sneered. And hundreds of thousands of ordinary American women indulged in plotlines involving S&M, bondage, and genital clamps without feeling guilty or ashamed. The trilogy showed how far we've come—not only since Lady Chatterley's Lover, but also in the last five years alone. Just as that little electronic device, the vibrator, radicalized sexual freedom, the e-book has turned women on to erotic literature in an unprecedented way.

Fifty Shades didn't open any startling new doors to a woman's secret chamber—it just modernized sado-masochistic fiction by merging it with chick lit. What was revolutionary, though, was that while Fifty Shades was popularized by word of mouth, it was in the intimate corners of the Nook, Kindle, and iPad that women had the chance to buy and read them easily and anonymously. In fact, the tomes were first released as e-books and print-on-demand paperbacks, and picked up by Vintage Books only after they went viral.

Women have always turned to romance novels to satisfy curiosities, explore secret fantasies, and get sexual pleasure. But until now, books with controversial feminist themes have been read under the covers. At first, novels such as Jane Eyre didn't even have to be sexy to imply that a woman reader had too much time on her hands and an overactive fantasy life (the horror!). As romance novels became more scandalous—with subjects such as children out-of-wedlock (Three Weeks), incest and abortion (Peyton Place), and "zipless fucks" (Fear of Flying)—the stigma of smut for sluts endured. Indeed, sex researchers, beginning with Alfred Kinsey in 1953's Sexual Behavior of the Human Female, declared that women, unlike men, were not aroused by pornographic prose. It was only around the time that Sex and the City broke all taboos about women openly comparing and rating sexual experiences that psychologists changed their views.

Today, erotic literature written by women for women has vigorously joined the marketplace. The key feature is that it's written by women; it's not a male fantasy imposed on women. Combine this thriving genre with the e-book, which is empowering women to seek out sexual satisfaction in private (no embarrassing Harlequin covers), even if the fantasies present women as submissive and powerless, it's likely the digital age will be remembered for giving women readers a new outlet for pleasure.

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