Tangled Roots : DIRT: The Ecstatic Skin of the Earth, <i> By William Bryant Logan (Riverhead Books: $22.95; 202 pp.)</i>

When I think about the land surrounding my house in the mountains of Upstate New York, I think of its extrusions: maple, birch and tamarack, Indian paintbrush and lupine, granite and schist. It is these, and not the poor, demineralized soil that makes them possible, that I see when I look out the window to the near and middle distance. Indeed, the soil is hardly ever what I see, not when I stand at the window or walk through the woods, and not when I close my eyes and compose a mental image of where I live. The soil is like its cousin, the air: necessary but invisible. It is so necessary in fact--not simply part of the landscape, but the landscape--that it disappears, at least from consciousness.

Where I live we have a garden. This year’s plot is smaller than last year’s, just a few fancy lettuces and an unruly patch of uncultivated tomatoes that have spawned spontaneously from seeds that spent the cold winter in the ground. We tilled the garden in the spring, the large red tiller bucking in the dirt like an untamed gelding, then laid on a layer of rich compost. The compost is medicine for gardens up here, for the soil is thin and tends to be acidic. Why it might be thin is nothing I ever much thought about--maybe it has to do with the mountains whose shadows shade my house, or maybe it has to do with the climate, which is rimy and intemperate, or maybe with the elevation, which is a few thousand feet above sea level. I can surmise and I can guess, but before I read William Bryant Logan’s marvelous new book, “Dirt: The Ecstatic Skin of the Earth,” can’t honestly say that I ever did.

Logan, who writes a monthly gardening column for the New York Times, spends most of his time in Manhattan, at the Cathedral of St. John the Divine, where he is writer in residence. A church may be a strange place for a writer to work (although what were the early monks but writers?), and New York City might seem an odd place for a man with an interest in the loam of the earth to live and, in any case, dirt may seem an unlikely subject of a book, especially a gleeful, poetic book. But none of these is more mysterious than the ground itself, and how it came to be, what it is made of what it nourishes. “Hospitality is the fundamental virtue of the soil. It makes room,” Logan writes. “It shares. It neutralizes poisons. And so it heals. This is what the soil teaches: If you want to be remembered, give yourself away.”

The subject of the essay from which this lesson is drawn is Phocas, the saint who dug his own grave before his executioners killed him, so he might feed the soil after his death. Logan is especially good at telling stories like this, stories that have a moral, yet are about something so essential--the foundation on which we live--that they defy notions of good and evil. If the spiritual dimension of the soil seems dubious, or forced, it should be remembered that it would not have seemed so to our ancestors. It is only in our own time, as agricultural memory fails, when most of our rituals honor ourselves and not those ingredients, like sun and water, which let us be ourselves, that the sacredness of the earth is not self-evident. We, after all, call it dirt, and understand it to be something to be gotten rid of.

Logan, however, is a man out of time, and it seems safe to say that he loves dirt. It excites him in a nearly erotic way. And it is the cause of great wonder, which is the essence of delight. “It is all impossible, after all: the earth, the dirt, and all these things that we do not know and that we did not make,” Logan writes in a chapter called “Stardust.” “’Let us worship the Lord in the beauty of holiness,”’ says the psalm. “What is beauty? Beauty is a sum not reducible to its parts. It is a perception of harmony in variety. What is worship? To worship means not to figure out, not to analyze, not to pin down like a dried butterfly on a grid, but to value. Deeply to value.”

Out in the field behind my house I can see the bed the doe made when she pawed the grass with her hoof, and the place in the sand where the turtle laid her eggs. The earth as a cradle is a cliche until you have witnessed it up close, enfolding. On a hot day it feels right to lie in the soft mud at the edge of the pond, leaving, upon rising, a faint impression of oneself. But too often, the impression we have been leaving on the earth has been more dramatic as we clear away topsoil for suburbs, pave it over for roads, subject it to erosion and to toxicity. Near where I live the county wanted to dig an enormous hole in the ground and bury all kinds of refuse, a plan that was eventually abandoned. But the refuse had to go somewhere, and that somewhere is connected to this somewhere, and so it is only a technicality to say that the dump did not end up in my back yard.

“Soil appears where life does,” Logan writes, “and its characteristic is to build where erosion destroys. On the face of a stone a lichen takes hold. The lichen digest minerals and is itself digested by the microbes in the air. The combined detritus falls, fills a cleft in the rock. A club moss roots in this compost, lives, and dies. The cleft overflows. Grass seeds blow in, grass grows.” Genesis, the psalms, and the Gospels--all are redolent here. Like the best natural histories, “Dirt” is a kind of prayer.