The campaign perhaps most associated with the new feminism, Dove's "Campaign for Real Beauty," slowly evolved into its current incarnation. The effort today shoots down stereotypical preconceptions about what makes a woman beautiful, but it began with a concept almost equally radical for beauty advertising during the time: it gave women a rational rather than emotional reason for buying the product. In their upcoming book, "Darling You Can't Do Both: And Other Noise to Ignore on Your Way Up," due out October, the creatives behind real beauty at Ogilvy & Mather, Janet Kestin and Nancy Vonk, trace the campaign's roots while making a compelling argument for why it's time to rethink the way women work.

In the early 1990s, as a newly minted creative team, we managed to incur the disdain of the advertising establishment right out of the gate when we shattered some time-honored rules in creating a campaign called "Dove Litmus Test." It proved to be pioneering. Not only did we help sell a stupid amount of soap, but "Litmus" paved the way for Dove's Campaign for Real Beauty, which reached millions of people and sparked a global debate about our culture's warped definition of beauty. For us, it ignited a personal interest in looking much more closely at what women are up against at home and at work.

The tipping point for Dove, and our careers, came when the brand's 35-year-old patent expired. Our new client at Lever, Peter Elwood, was worried that a competitor had a clone in the works. This was the first time in years that Dove's comfy spot at the top of the soap aisle looked shaky. We agreed with him: the bar with "¼ moisturizing cream" needed a face-lift.

Because we were new to Dove's marketing team, Peter thought we should understand the product fundamentals. He organized a technical briefing where people in lab coats gave us a crash course on all the unique aspects of the bar we'd grown up with. We learned that Dove isn't a soap, technically. It has a non-soap ingredient developed during World War II to clean the skin of burn victims. Because of that, Dove is pH neutral, one of the fundamental reasons it's easier on skin: "It doesn't strip away skin oils like soap do. 'Squeaky clean' skin is actually dried out, easily irritated."

"Which soaps?"

"All soaps."

Do you remember those yellow litmus papers from high school science class? Our new friends in the Lever lab told us that if you pressed one up against a wet bar of Dove, it wouldn't change color because Dove is pH neutral, while the other soaps would instantly turn the strip dark blue, indicating high alkalinity. They showed us the jolting color change with five or six soaps, including a "baby soap," to demonstrate that they were all about the same when it came to pH. They gave us examples of things that are alkaline, things that are acidic and things that are pH neutral, for context.

Their little chemistry lesson was a gripper. This was an unexpected way to see the big difference between Dove and all its competitors, but we had to try it ourselves to really believe it. We swept dozens of soaps off the shelf at a nearby drugstore and took over a boardroom back at the office to do our own pH tests. Those little yellow papers turned ink blue again and again and again. Every single bar had about the same pH as Mr. Clean. No, that didn't mean they'd peel the skin off the user. But that level of alkalinity struck us as rather aggressive. We felt duped by those brands' ads that blathered on about how mild, gentle, natural and pure their product was.

Sitting on overstuffed couches at Janet's house with Persian tea in hand, we generated a carpet of quickly sketched storyboards as we tackled the advertising challenge. In a single morning we decided to pitch a campaign to Peter that would recreate in the minds of TV viewers the exact feeling we had when we did the test.

The campaign we produced was literally a litmus test. Unlike any Dove ad before it, "Litmus" didn't show any women, save for a hand. And in another unconventional move, there was no voice commenting on what was happening to lead the viewer, because we wanted this story to be told objectively. Finally, we didn't end with the "pour shot" -- the sacred sign-off through decades of Dove commercials where moisturizer is magically poured into the shape of a bar of Dove. In this context we thought it would seem gimmicky and distracting. The headline in magazine ads asked, "Do you really need the alkalinity of a household cleaner to wash your face?" The reader would write away for free litmus paper so she could test her own brand. She didn't need to take our word for it, she could see for herself and decided how she felt.

The campaign was perceived as an enormous risk by top brass at both Ogilvy & Mather, our agency, and Lever in New York. They were not impressed when they saw what we were doing in Canada. We were breaking rules that had been carved in stone not only for Dove but for the larger world of advertising. David Ogilvy, the legendary agency founder, had famously created Dove's first ad campaign. Who were we to mess with decades of success?

Ogilvy himself wrote a scolding letter saying "science won't sell." But the consumer didn't see it that way. Dove sales went through the roof and their main competitors' took a nose dive. The campaign reframed Dove and challenged the way other brands were talking to women. It gave them a compelling, intelligent reason to buy a product and didn't condescend to female stereotypes.

"Litmus" was the blueprint for our success. It was about risk taking and authenticity. There was reward for finding inspiration in unconventional places, listening to unconventional voices and speaking the truth.