"The best writers were also the best lovers ."

That is the conclusion of Mary Kathleen Benet after studying the literary and personal lives of Katherine Manfield, George Eliot and Colette - three of the Western world's greatest women writers. But it's not as juicy as it sounds. What Benet, the grandniece of Stephen Vincent Benet, is really saying, in a serious, scholarly way, is that the achievement of these three women was made possible by their uncommon ability to combine love and work, and that behind each of them stood an unusual man. John Middleton Murry, George Henry Lewes and Maurice Goudeket, respectively gave Mansfield, Eliot and Colette the tender loving care vital to their artistic success. Rare creatures, these men. They were willing, even eager, to devote their own talents and energies to furthering the careers of the women they loved.

Mansfield, Eliot and Colette provide rich material for comparison. All were country girls, "outsiders" when they first approached the literary scene. Each rejected traditional deomesticity, but found love a vital prerequisite to a creative life. They refused to choose between love and work as so many gifted women felt compelled to choose - Emily Bronte, for example, who chose work (and emotional isolation) or Jane Carlyle, who chose marriage to Thomas Carlyle (and a sublimated artistic life for herself). Mansfield, Eliot and Colette demanded both love and work. And this, says Benet, is the very reason their creative genius bloomed. An interesting theory, which Benet expounds in a painstaking, sometimes laborious fashion, and like all theories, it fits some cases better than others. George Eliot's career flowered only when she ran off to live with Lewes, whereas Colette had many productive years - and two unhappy marriages - behind her before Goudeket came into her life.

Benet sounds a battle cry of sorts for the liberation of exceptionally creative women. Thanks to the women's movement, the notion that women of genius are entitled to the same nurturing and care as man, now seems scarcely revolutionary. But the imaginative way these three extraordinarily talented women writers were able to put aside the conventions of the day and arrange unconventional lives which suited them emotionally and rewarded them artistically may, as Benet says, contain a lesson for us all. (Macmillan, $9.95)