HONG KONG (AFP) ― In her own words, Erica Jong wanted to “slice open a woman’s head and show everything happening inside” when she wrote her debut novel “Fear of Flying,” first published 40 years ago.

The book, which is set for an anniversary re-release this year, became a sensation in 1973 and went on to shift more than 20 million copies in 40 different languages. But reaction to it also illustrated that the inside of a woman’s head ― at least as Jong saw it ― could be a polarizing place.

“You can tell when a book matters when people argue about it,” the 71-year-old author and ardent feminist told AFP in an interview.

“Some people hate it, some people love it,” she said of her debut novel. “I think that’s what writers are made to do ― we’re the earthworms, we aerate the soil. I’m proud of that.”

The story of Isadora Wing, who is five years into her second marriage to a psychiatrist but laments that sex with him now brings “no thrill to the tastebuds, no bittersweet edge, no danger,” struck a chord with millions.

In 1973, such uninhibited sexual frankness and liberal swearing from a female perspective caused a stir in the publishing world. In the book, Wing rages that “men have always defined femininity as a means of keeping women in line.”

Jong says she had wanted to explore sex in the way Philip Roth and John Updike had done ― but from a female mindset. The difference in the way she was treated, she says, smacked of an inequality that continues to this day.

“I have come to understand what it’s like to be a woman writer in a world in which women are still looked at as breasts and pussies,” the typically blunt New York-born author said.

“I have learned from my journey that we are absolutely not equal yet.”

When “Fear of Flying” turned 20 in 1993, she wrote that her aim had been to give a “rallying cry for women who wanted the right to have fantasies as rich and raunchy as those of men.”

Some reviewers were scathing. American writer Paul Theroux referred to the character of Wing as a “mammoth pudenda.”

Given how the story blurred fiction with autobiography, Jong said the experience of such criticism “was very stressful at the beginning, and in order to survive I developed a sense of humour about it.”

Her website proudly explains how she “evidently lives by the liberal mores she advocates”: she has been married four times ― with the Jong part of her name coming from her third marriage ― and her current husband is a divorce lawyer. She also has a daughter, writer and satirist Molly Jong-Fast.

Before her debut stole the limelight, Jong started out as an award-winning poet, publishing a collection of erotic poetry “Fruits and Vegetables” in 1971.

She has written more than 20 books, including 10 works of fiction as well as non-fiction. She says her next novel is a comic take on death.

Of course much has changed since 1973, when “Fear of Flying” was published, and younger generations discovering the book for the first time are doing so in a world more accustomed to instant gratification.

“We have the hook-up culture now where people meet for 20 minutes and have perfunctory sex,” said Jong. “But young women and young men are so disillusioned with it, because it turns out that anonymous sex is not very satisfying without any feeling.