TWENTY YEARS AGO, Betty Friedan wrote what is now considered to be the original feminist bible: The Feminine Mystique. Setting the tone for the bra-burning feminists of the 1960's. Friedan began a revolutionary and radical questioning of a woman's place in society. Since then, the polemical rhetoric of the women's movement's early stages has gradually been replaced by a more moderate and rational argument for sexual equality. More and more feminists are asserting that women can be "different but equal."

In her curiously passive book, Susan Brownmiller examines the historical basis for the wide range of ways in which men and women differ. Brownmiller invokes the concept of a "feminine ethic" and proffers numerous literary and historical anecdotes to support the idea of a feminine sphere of behavior Ultimately, though, Brownmiller ends most of her chapters with questions, not answers, and if she intended to leave her readers with a message, it is indecipherable.

Femininity begins with a discussion of how, women through the ages have altered and disguised their bodies to fit the latest fashion "Appearance, not accomplishment is the feminine demonstration of desirability and worth." Brownmiller blithely asserts, Brownmiller opens with this safe discussion of corsets and diets, and continues her litany with a list of less obvious feminine shackles.

After discussing discrepancies between men and women in hair, clothes, voice and skin. Brownmiller moves to the more nebulous categories of emotion and ambition. Throughout the book, she attempts to define and come to grips with a "feminine ethic" which she views as both confining and positive.

In a world out of balance, where men are taught to value toughness and linear vision as masculine traits that enable them to think strategically from conquest to conquest, from campaign to campaign without looking back, without getting sidetracked by vulnerable feelings, there is, and will be, an emotional difference between the sexes, a gender gap that may even appear on a Gallup poll.

With a degree of resignation, Brownmiller seems to accept a wide range of restrictions--physical, emotional and otherwise--which society has placed on women. In many instances, Brownmiller herself buys into the many myths about women. "Love of babies, any baby and all babies, not only one's own, is a celebrated and anticipated feminine emotion," she writes.

But after showing a certain range of emotions which women are expected to feel. Brownmiller can only question this disparity between men and women in the most cautious terms. "It would be premature to answer" the question of whether there is a natural gender-specific set of emotions. One would like to ask Brownmiller who she expects will provide the answer--and when.

Brownmiller correctly points out that "the singlemindedness with which a man may pursue his non-reproductive goals is foreign not only to the female procreational ability, it is alien to the feminine values and emotional traits that women are expected to show." But implicit in this statement is the value judgment that such singlemindedness is a good trait. The author ends her book with a chapter titled "Ambition." Why not end it with a chapter titled "Compassion"? Perhaps comparisons of men and women should begin with a questioning of male-dictated criteria of evaluation.

MANY OF THE FIRST radical feminists not only detested men, but also criticized women harshly. They caricatured and decried prototypical female role models. Betty Friedan called suburban households "comfortable concentration camps" for married women, implying that it was up to these women to improve their own lives. But Friedan's criticism was aimed principally at middle class housewives. Later feminists recognized that women's problems are not merely self-imposed by a certain socioeconomic class of woman, but are endemic and imposed by a historically sexist society.

Brownmiller offers exhaustive proof of the historical basis for sexism, but she offers no solutions. She concludes the book by saying that "there are no easy answers" to the many central questions which she has posed. For this reason, Femininity offers no real step forward in feminist though. Highly personal and packed with lively anecdotes--both autobiographical and historical --the book nevertheless fails to offer any fresh insights. Instead, a current of resentment runs throughout, as though Brownmiller wrote Femininity to purge the curtseys of her youth and high heels of her adulthood.

"Perhaps the cruelest part of femininity is that it does not age well." Perhaps not, but neither does a feminism that chronicles the past with no eye toward the future.