Many of us remember from childhood a particularly influential teacher whose strong personality has assured her (or his) presence in memory. If contact with that teacher continues into adult life, it inevitably assumes a different form. May Sarton's "The Magnificent Spinster" -- her 18th novel -- takes the form of a reminiscence of such a special bond.

The narrator, Cam Arnold, first knew Jane Reid at the Warren School, a progressive school in Boston. Fifty years later, after Jane's death, Cam feels compelled to preserve for others the life of an extraordinary friend and mentor who left no descendants. As a medieval historian at a small college, Cam feels both uniquely qualified and also unqualified for her task. Not only must she include details of her own life in the process of recording Jane's, but she must present some events about which she has little information. Thus she casts Jane Reid's life in the form of a novel, allowing herself the liberty of invented dialogues and descriptive details.

Simultaneously inside and outside her story, Cam struggles with her subject; her meditations on the difficulty of writing a "life" are interpolated at various points in the narrative and serve as prologues to four of its six sections. As a minor character observes, "no biography ever tells the whole truth. It is truth filtered through someone's mind . . ." Through the persona of Cam Arnold, May Sarton ingeniously creates a fiction within a fiction to commemorate a woman who influenced her own life. (Sarton's book is dedicated to Anne Longfellow Thorp, 1894-1977.)

The fictional Jane Reid is one of five daughters of a Boston Brahmin family -- the last of a leisure class that tempered wealth and position with noblesse oblige. Jane's childhood summers in Maine are complete with tennis, boating parties and a nanny named Snooker. Later, disdaining her family's traditional preference for Radcliffe, Jane is educated at Vassar. Though she never marries (despite several opportunities), at 38 she makes the daring decision to marry "solitude" by building a house of her own. After it is completed, she settles in to her vocation as a gifted teacher and "universal friend."

Cam Arnold's initial encounter with Jane Reid -- as her teacher for seventh-grade history and English -- is a transforming experience; as she recognizes in retrospect, she and her peers were "fertilized as sentient beings" by Jane's mind and spirit. "Role model" (the narrator's term) is too prosaic to describe the decisive impress Jane Reid makes on Cam, who becomes a teacher herself and emulates her mentor's intellectual passion.

As novelist-biographer, Cam traces the course of Jane Reid's life, during various points of which their paths cross as she seeks out her mentor for solace, advice and friendship. Endowed with the rare capacity to enter imaginatively into other people's deepest dreams and fears, Jane Reid enables her friends to realize themselves by providing not only spiritual but also occasional financial support. Thus, while disagreeing with Cam's radical politics, Jane subsidizes the latter's travel to Spain as a volunteer during the Civil War. When the battle-stunned Cam returns, stripped of her idealism and psychic engergy, Jane nurtures her to recovery.

Jane Reid and Cam Arnold represent different generations and different kinds of social conscience. Jane's enterprises take the form of volunteer work -- as a hospital aide during an acute influenza epidemic in Boston; as part of a team that organizes a "neighborhood house" in the war-ravaged city of Bremen, Germany, after World War II. Cam, retreating to a more cloistered life, envies the way Jane Reid's life "opened out just in the years when hers was closing in."

Other sisters, nieces and friends move in and out of the two women's lives, the most important of whom is Ruth, Cam's partner for 20 years. Ruth's sudden death is described with great poignance and sensitivity.

Yet despite its celebration of female friendship, "The Magnificent Spinster" is only a qualified success. The narrator's struggle to find the form and expression for her appreciation of Jane Reid no doubt mirrors Sarton's own artistic struggle. The life of a saint is difficult to write (and read). Jane is so idealized that she becomes unbelievable; she has few negative qualities, no dark side, no deep struggles with her choices. Her exemplary benevolence seems almost too good to be sure. Certain details and phrases -- the perennial "twinkle" in "Aunt Reedy's" eye and her characteristic comments ("bless his heart" and "dearie") become almost cloying.

The result is a work that, as either a novel or a fictionalized reminiscence, lacks tension and complexity. Although the reader has a clear portrait of Jane Reid by the novel's end, her "magnificence" somehow escapes the nets of biography and fiction.