What would possess a young married couple to sell their home in California and buy an island off the coast of Maine? And what would keep them there, living in rustic isolation, for the next four decades?

In the case of Art and Nan Kellam, we may never know for sure. But a splendid new book by Peter P. Blanchard III, graced with photographs by David Graham, takes us into the heart of the mystery, at least. Drawing upon the Kellams’ journals as well as interviews with residents of nearby communities, We Were An Island (University Press of New England, Dartmouth, New Hampshire; Hardcover; 212 pages; $27.95) takes us into the lives of a pair of fascinating eccentrics who carried the idea of getting away from it all to a remarkable extreme.

The Kellams’ journey Down East began in the aftermath of World War II. Art had done some classified aeronautics work during the war, and it’s possible — though far from certain — that he was repulsed by the barbaric potential of technology. If so, he seems never to have written or spoken about it. Nan was nearly as mum, though she referred obliquely in a journal entry to “the diverting complications of modern civilized existence.”

Whatever their reasons, the Kellams began searching along both East and West coasts for a place where they could put the bustling world behind them. They settled eventually on Placentia Island, 550 acres of fields and tall spruces in Blue Hill Bay, a couple miles south of Bar Harbor. No one had lived there for decades, but an old barn provided temporary shelter until Art could build, with local assistance, a small house they named Homewood. Here they lived for four decades with no running water, no electricity, no means of communication except for a signal flag that could be run up in an emergency.

They took up residence in June 1949.

Their journals from this period reveal a state of high excitement. “What wealth,” Nan wrote, “might oneexchange for these beautiful days and nites [sic] and our glorious freedom!”

In some ways this story resembles that of other, better-known back-to-the-landers, before and since, who have come to Maine seeking a simpler, more natural life. In other respects the Kellams stand out. They would seem, for starters, to have been temperamentally unsuited to their new lifestyle. Neither liked to cook. They showed little interest in gardening; apart from half-hearted efforts to grow a few vegetables, their preferred means of sustenance consisted of regular shopping runs, by rowboat, to the grocery store in Bar Harbor. They never took up fishing, despite being surrounded by water. They don’t seem to have been especially health-conscious; Art was and remained a chain-smoker. And though they devoted time each day to writing — extensive journal-keeping for which they invented a private language (“geums” for cigarettes, “zooners” for mosquitoes) — neither troubled to explain exactly what they were doing out there, what they were looking for, or whether they found it.

Given these unusual circumstances, it is no mean feat for Peter Blanchard, in this volume, to have brought some sense and structure to the Kellams’ enigmatic lives. Blanchard, a longtime conservationist, first visited the island after Art’s death in 1985, while Nan was still in solitary tenancy. (She would eventually move to a retirement community in Bar Harbor, dying there in 2002.) Blanchard had come as the representative of the Nature Conservancy, to which the Kellams had bequeathed their land. It was in this capacity that he ultimately gained access to the couple’s private writings, along with a modest trove of home photos, newspaper clippings, and other tokens of their time on Placentia. He has done a masterful job of weaving this hodgepodge of source material into a lively and persuasive narrative that is evocatively illustrated by David Graham’s photographs. The finished volume gives us an intimate and rather bittersweet sense of place, taking us through the mental and physical landscapes of lives already vanishing into the past.