For me, it is the dogs and the lesbians. These were the sections in Nancy Friday’s 1973 cult sexuality tome, My Secret Garden: Women’s Sexual Fantasies, that I can still recall. As a 10-year-old, I sneaked endless peeks of it (alongside Jacqueline Susann and The Joy of Sex) from my mother’s bookshelf. The clumsiness in expression of many of Friday’s interviewees is a poignant testament to the raw honesty behind the confessions. The housewife “Jo” who fantasised about her neighbour’s dog during her afternoon baking session is compulsive reading.

My Secret Garden exploded on to bestseller lists around the globe in 1973. The work was shocking, deeply sexy in parts and proved that women had erotic imaginations just as men did, and that they, too, masturbated just as men did. It heralded the innocent dawning of what later became known as the sex-positive feminist movement. My Secret Garden came at the beginning of a wave of overtly sexual content written by women. Also in 1973, Betty Dodson penned what was to become the world’s bestseller on masturbation, Sex for One. My Secret Garden didn’t have the gravitas and respectability of say, Shulamith Firestone, but as author Susie Bright, the original “Sexpert” in the 1980s and 90s, says, “it sold millions and millions of copies and was a big wake-up for America’s puritanical, sheltered girls and young women”.

Of course, Friday was attacked by many. Like Dodson, her work was dismissed for being not scientific enough or for being too personal, or too much like soft porn. But an even bigger issue was that she wasn’t, Bright recalls with glee, “the tiniest bit politically correct”.

There is something quite secret about My Secret Garden. All Friday’s interviewees, who talk about fantasies ranging from being sex workers to being urinated on, talk anonymously.One interviewee explains how, when she has sex with her husband, her fantasy is imagining “the bed practically torn apart and us ending up on the floor wet and sticky and happy”. The reality though is that, “All he’s really doing is lying on top of me and thrusting away.

In 1996, Friday told Salon: “I would no more go to a consciousness-raising group and talk about my intimate life with my husband than fly to the moon.” In that same year, while discussing sexual harassment in the office on Bill Maher’s Comedy Central talk show Politically Incorrect, she claimed that men suffered from harassment as much as women.

Nancy Friday’s legacy is that My Secret Garden still inspires a younger generation of women. Photograph: rec

And so she found herself in the firing line of the feminist sex wars before that concept had even properly taken shape. Ms magazine wrote of her: “This woman is not a feminist.” But her background was not in feminism and she had no community of “sisters”. Bright adds that Friday was “hurt” when she was denounced by feminists. “She wasn’t a political mind,” says Bright. “But she was a superb interviewer, and a good journalist.” Born in Pittsburgh and later attending the prestigious Wellesley College in Massachusetts, Friday started life as a magazine reporter before having the idea, which she reiterates in the introduction to My Secret Garden, that, “In trying to understand what it is to be a woman, neither nationality nor class helps to define us so much as the honesty of our feelings about ourselves and our desires.”

Today, we take a lot of sex-positive talk about women for granted. And, with a 21st-century eye, we might have hoped for Friday to have gone a little further in her delvings into female sexuality.

But if some women didn’t know what a fantasy was, then many more had no idea what an orgasm was or how to get one. Dodson made it her life’s work to show women how to do that – to go beyond the fantasy and get to the nuts and bolts of how your sexual body actually works. But Friday had another path. Her third book, My Mother/My Self: The Daughter’s Search for Identity (1977) is a fascinating, reflective and critically acclaimed look at why so many of her previous interviewees had such deep feelings of guilt about sex.

Friday died on Sunday 5 November, aged 84. Her legacy is that My Secret Garden still inspires a younger generation with its bold, embarrassing honesty, and Bright gives her own advice for a rereading: “Don’t read the analysis, read the stories, then think of your own.”

Stephanie Theobald is the author of Sex Drive