It Begins With a Spark : A bolt of lightning disrupted Gretel Ehrlich’s life and her health, but it also set her on a quest to understand where the breath of life comes from. : A MATCH TO THE HEART, <i> By Gretel Ehrlich (Pantheon: $21; 201 pp.)</i>

At five o’clock one threatening afternoon barely two years ago, Gretel Ehrlich was struck by lighting. Of this event that profoundly and permanently altered her life she writes: “Before electricity carved its blue path toward me, before the negative charge shot down from cloud to ground, before ‘streamers’ jumped the positive charge back up from the ground to cloud, before air expanded and contracted producing loud pressure pulses I could not hear because I was already dead, I had been walking.”

“A Match to the Heart” is the affecting, gorgeously written chronicle of Ehrlich’s subsequent struggle toward, if not recovery, at least balance. Against the arbitrary bad luck of having been in the wrong place at the wrong time, she searches for a sense of understanding, of acceptance, even as her body resists recuperation. It is a long and difficult journey, a continuing process, but guided by Gretel Ehrlich’s passionate and unflinching inquiry into the scientific causes of lightning, the delicate intricacies of the body, and the battle between stoicism and determined will, we emerge, with her, wiser than we began. Along the way we are privy to an introspective autobiography splendidly rendered.

With her first book, “The Solace of Open Spaces” (1985), Gretel Ehrlich proved herself to be a prose poet of impressive talent and breadth. Her vivid, intelligent meditations on the land, especially the wide horizons of a Wyoming ranch, invited readers to experience an almost mystical connection to an environment few had ever known directly. In the work that followed--a memorable essay in “Legacy of Light” (1987); a novel, “Heart Mountain” (1988); stories, “Drinking Dry Clouds” (1991); and the nonfiction “Islands, The Universe, Home” (1991)--she continued to hone and perfect her vision, garnering along the way a devoted and enthusiastic following.

My reading copy of “A Match to the Heart” is marked with almost as many turned down corners as it has pages, with countless underlinings and notes. A passage or two I’ve committed to memory, for both the pleasure and the instruction in the creation of fine descriptive literature it provides. How to choose between them for this review?

When Gretel Ehrlich looks out on the Pacific, for instance, she doesn’t just see waves. On one occasion, she “watched a slivered moon move west, its back hunched to the winter sun.” On another, “Purple changed to blue dappled with pink: the water was a shield, reflecting what was above, below, inside each wave. The waves started blue, ribbed black, ended white. Where kelp beds floated, the sea was bright like ice. Two pelicans skimmed whitecaps with their wingtips, and farther out a hidden reef broke waves the way irony breaks open certain truths.” And later: “Most of us are so earthbound, so terracentric, we think of the continent as the centerpiece around whose edges oceans lap. But to a set of waves journeying across the Pacific, the sea is the central body into which the lithosphere rudely bumps. The life of a wave ends at the edge of the continent where water becomes shallow. As they approach the shore, their length suddenly decreases, and to compensate, the waves slow down and steepen. The shallow bottom refracts waves: they are bent, not by a twist of wind but by the shape of the ocean floor. For a moment the wave is a mirror image of underwater contours.”

“A Match to the Heart” similarly echoes the very essence of the elements it records: water, the fire of lighting, the sturdy utility of Wyoming earth, the blissful dynamic of air. It also poses answers to that most personal of questions: Who am I? “How odd,” Ehrlich considers, “that we walk around with these bodies, live in them, die in them, make love with them, yet know almost nothing of their intimate workings, the ludicrous balancing act of homeostasis, the delicate architecture of their organs and systems, or the varying weathers of their private, internal environments. Up to this point my living and breathing had been an act of faith. I existed but I didn’t know how”--a gap in her knowledge she aims at least partially to rectify.

Witnessing open-heart surgery to better grasp the mystery of the organ she sought to heal in herself, Ehrlich says: “I was a traveler, a Marco Polo who had arrived in a place so exotic, few had seen it before. . . . Steam rose from the open cavity. I felt as if I had broken into a hidden cave and come upon rubies and sapphires. Looking past skin, red tissue, white bone, into a chest held open by a steel frame, I saw a beating heart.”

She stands in awe of both the mechanisms of life and the vocabularies used to approximate them. “An intake of breath is not just oxygen, a pulse is not just the rush of blood but also the taking in of divinity through an orifice, and as it moves through, it becomes a spark. To be inspired is to have accepted spirit in the lungs and heart, to watch it circulate through miles of blood vessels and capillaries whose tiny fenestrations allow oxygen, nutrients, and grace to leak into the tissues of muscle and consciousness, then be taken up again, reoxygenated, and returned.”

Turning her attention to the brain, she declares: “The synapse is holy. Apse comes from apsis, whose roots mean, to loop, wheel, arch, orbit, fasten, or copulate, and the apse of a church is a place of honor. The synapse is the gap where nothing and everything happens. Bodies of thoughts swim in the synaptic lake, sliding over receptors, reaching for the ones that live on the other shore. An interval of between 0.5 and 1 millisecond transpires before an impulse makes its way across the gap . . . where we pause between life and death, treading water in the oblivion of a gray sea. What is a thought before it registers memory? . . . Is it like unrequited love, or a lover who is spirit only, who has no body?”

“There are about 1,800 thunderstorms in progress over the earth every moment,” we learn, “and lightning hits the planet one hundred times each second. In the continental United States alone, there are forty million cloud-to-ground strikes each year.” One of them, by pure chance, hit Gretel Ehrlich and changed her life forever. In response, she produced “A Match to the Heart”--a dazzling work of art--and so changes ours.