Mrs. Emerson, I presume?

After Ralph Waldo Emerson wooed and won Lydia Jackson, he told her he wanted to call her "Lydian." Lydia, he said, was a common female name, but Lidian (as he spelled it) had both musical and classical echoes.

It was more than a lover's name game for Emerson. He was defining Lidian as the wife he wanted.

She acquiesced - but then responded by calling him "Mr. Emerson" for the rest of their more than 40-year marriage.

"Mr. Emerson's Wife" explores the complex relationship of the famous philosopher and his less well known partner in a novel that has a sturdy fabric of fact, embroidered with imagined events and emotions.

Amy Belding Brown tells Lidian's story in a first-person narrative, describing feelings and thoughts that go beyond anything recorded in the reams of letters and journals left behind by the principal actors in her drama.

The Emersons set up housekeeping in Concord, Mass., to "create a country haven for scholars and philosophers ... a center of refinement and transcendent thought."

Emerson was already a popular lecturer and noted writer. Lidian was a thoughtful intellectual, well-read in philosophy and religion. A matched pair, it would seem.

Yet Emerson made it clear to Lidian from the start that while he cherished and admired her, the real love of his life would always be his first wife, Ellen, who had died early in that marriage. Lidian, however, found ways to assert her own claims on her husband's heart. When her second child was born she named her Ellen, hoping that Emerson would come to think primarily of his daughter when he heard the name.

Household cares soon absorbed Lidian's time.

Members of both their families lived in their large house at various times, and then the children began to arrive.

Lidian was frequently ill and often bedridden. Her husband retreated to his study every morning to write, emerging for walks with young disciples like Henry David Thoreau and Margaret Fuller or talks with Bronson Alcott.

Brown's writing is graceful, at times giving Lidian a poetic voice.

"I did not believe my roses would bloom again after my son died [5-year-old Wallie]," she writes. "Yet that June, as always, the damasks raised their tight pink fists to the sky, and the sun peeled them open, petal by fragile petal."

Emerson had early recognized Thoreau's literary talent and encouraged him by providing him with a small upstairs room in their home in which he could live and write, uninterrupted by the commotion in his mother's boarding house.

Thoreau was the resident handyman for several years, greatly loved by the Emerson children and much appreciated by the harried housewife.

From Thoreau's own letters and journals, it's clear that he deeply admired and loved Lidian.

"The thought of you will constantly elevate my life; it will be something always above the horizon to behold, as when I look up at the evening star. I think I know your thoughts without seeing you, and as well here as in Concord. You are not at all strange to me," he wrote from New York.

But was the relationship more than an elder sister/younger brother bond? Was there - literally - a roll in the hayloft, creating some doubt about who was the father of Lidian's last child, Edward?

In an age when scholarly biographers meticulously document every detail in the actions and settings of their subjects, Brown has escaped to the freedom of fiction to suppose "what might have been."

Fascinated - or frustrated - readers must look beyond the confines of this novel to sort out fact and fancy.

• Ruth Johnstone Wales is a former Monitor editor.