One year my wife and I had a live Christmas tree, which, its root structure intact, sat in a tub in the living room. After the holidays were over, we put the tree on the front porch where it acclimated itself to the cold weather, and in the spring we planted it in the front yard. Although the tree got off to an uncertain start - our mailman once said that he had wondered whether it would survive - it took hold, flourished, and is now about 20 feet high, perhaps four times its height when, as a Christmas tree, it winked in our front window.
I mention the provenance of this evergreen tree for in my imagination the tree, having been in the woods and then domesticated, is edging back toward the wilderness. In fact, late in the spring, looking up into the tree's dense branches, I noticed a bird's nest and, barely distinguishable against the green foliage, a turtledove sitting in the nest.
At about the same time, on my hands and knees in the garden, I came face to face with a wildflower - a pansy - and was startled to see it growing up amid the tall grass against the fence line.
The wild pansy in my backyard and the brooding turtledove in my front yard reminded me that nature is often close at hand and that even a narrowly circumscribed city lot may contain intimations of that far more magnificent wilderness lying just beyond the last suburban tract house.
For me, the intimations of that wilderness are sufficient for most of my moods. I do not need to go to the woods, as did Thoreau, ''to live deliberately, to front only the essential facts of life. . . .'' Though I would live simply, as did Thoreau, for me living simply means living in a city, where I can walk or bike to my job and the store and where I need be responsible for only a few square feet of lawn rather than for acres of fields. Thus in my own way I fulfill Thoreau's command to simplify.
Thoreau brings me back to my turtledove. In a famous and enigmatic passage in ''Walden,'' he said that he ''long ago lost a hound, a bay horse, and a turtle-dove. . . .'' Critics have long puzzled over the meaning of that phrase, nor have I any insight that might help elucidate it. I can imagine, however, my turtledove's being Thoreau's lost turtledove, coming to me across a century and a half in years, and from New England to Wisconsin, a thousand miles or more in distance.
But if for Thoreau the lost turtledove represented a failure in his life, for me the found turtledove represented an achievement - the idea that elements of nature may be no farther away than my own yard, and that they intimate a far richer and wilder nature waiting for me beyond the last artifacts of civilization.