The Magnificent Spinster by May Sarton (Norton: $16.95; 374 pp.)

“The Magnificent Spinster” is a novel about writing a novel, which is really a biography. May Sarton writes about Cam, who is writing a biographical fiction about her great friend and former teacher, Jane.

Sarton plays merry with these boundaries between biography, autobiography and fiction. Cam’s insights about literature as well as the actual practice of literature in this book are provocative. “The Magnificent Spinster” is also fascinating for its vibrant portrayal of old women.

Sarton, herself a rather magnificent spinster, is often overlooked by critics. She has published 17 previous novels, 14 collections of poetry and 8 books of nonfiction. Some people miss her brilliant simplicity and understated social commitment. Some miss the private vulnerability and courage, unaware that Sarton lost her teaching jobs in 1965 for the lesbianism in her fiction. Cam’s voice will be familiar to many loyal Sarton readers; like the protagonists of her other novels, Cam is a charming, intellectual woman of elegant passion, and very much her own person.

Cam, a retired history professor, worries that Jane Reid’s story may disappear because she has no children to pass on her laurel. Cam comes home from Jane’s funeral and starts to write about their friendship of almost 60 years. Her project demands serious research into Jane’s life as well as long hours of contemplation during which Cam has a chance to examine her own life. She chooses the novel form rather than a memoir or a conventional biography because “The essence was what mattered, after all.”

Born a Boston Brahmin in 1896, Jane is one of five girls in a comfortable, tranquil family tracing heritage back to the illustrious writer Benjamin Trueblood. Jane passes an idyllic childhood between her family home and the summer cottage in Maine. After graduating from Vassar, she travels to France to work with children orphaned during World War I. She returns to teach at Warren School in Cambridge and to work as a community activist. Throughout her life, Jane exudes a radiant talent for friendship.

Meanwhile, Cam grows up under Jane’s inspiration, attends Vassar, sets off for the Spanish Civil War, returns to teach history in a small New England college and continues to enjoy Jane’s friendship. Sarton is at her best sculpting the distinctive personalities of these friends--balancing Cam’s rash enthusiasm with Jane’s delicate restraint and showing how their relationship thrives despite and because of these differences.

It is the private greatness of Jane and Cam that makes “The Magnificent Spinster” extraordinary. The book’s power lies not in the protagonists’ high drama, but rather in the quality of their deeply engaged days.

Sarton reclaims the word spinster for both women as they spin in their different directions. Cam describes Jane, “ ‘She was never virginal,’ and I supposed what I meant was that she did not resemble anyone’s idea of a spinster, dried up, afraid of life, locked away. On the contrary, it may have been her riches as a personality, her openness, the depth of her feelings that made her what she was, not quite the marrying kind . . . a free spirit.”

Cam, who spins the tale for both of them, settles down with her lesbian partner Ruth. Being spinsters allows both Jane and Cam to contribute to the world with time and spirit unavailable to their friends who are reproducing and rearing families.

The descriptions of aging are fascinating as May Sarton, a 73-year-old novelist, is writing about Cam, a 70-year-old historian, who is writing about Jane, who recently died at 86. Vitality is the hallmark of each woman. Neither sages nor victims of senility, Cam and Jane and their friends come across with refreshing individuality, “. . . one trouble with all the statistics and all the generalities is that old age is as singular an experience for each person as childhood is.” Of course Sarton has given us other old women in her novels, “As We Are Now,” “Mrs. Stevens Hears the Mermaids Singing” and “A Reckoning” as well as in her best-selling journal, “At Seventy.”

The relationship between author and subject provides creative tension throughout “The Magnificent Spinster.” Jane is struggling to find a biographer who will honor grandfather Benjamin Trueblood’s work without distorting his life. And the character of Jane is based on Sarton’s own former teacher, Anne Longfellow Thorp, to whom “The Magnificent Spinster” is dedicated. The stories of Trueblood and Jane may have special resonance for Sarton, at the point in her own life when she is considering the question of her biographer. Cam ponders the loopholes of life stories, “I am gliding over a great deal because this novel is not about me, yet I am present in it as narrator. So I have to exist as myself as I write, and this is proving awfully hard to do.”

Whether we’re reading Cam’s book about Jane or Sarton’s book about Cam’s book, the writers are like portrait photographers who work facing a mirror. When the picture is developed, two central figures are exposed.