It's the first day of February, the month that in the north temperate zone is usually devoted to teeth-gritting and finding a way to hang on until March and signs of spring. So you can imagine my thrill when, in the early gray of this morning's commute through central Maryland, I heard what sounded like the honking of Canada geese. Certain it had to be something else, such as a truck in trouble, but hoping for the best, I peered up through my car windshield to see a dark black vee, heading northeast. Sure enough, geese were flying overhead, announcing their intent to head north for nesting.

The annual performance of goose music had begun, and I knew Aldo Leopold would be happy to find the show still running. Leopold's essay entitled "Goose Music" can now be found together with many of his Round River essays in an expanded version of A Sand County Almanac (Ballantine Books; paperback, $6.99), which was first published posthumously in 1949. Leopold, then a game management professor at the University of Wisconsin, Madison, died in 1948 at the age of 61 while fighting a brush fire on a neighbor's farm. One of the founders of the Wilderness Society, Leopold had helped establish, in 1924, the first forest wilderness area in the United States, now the Gila National Forest in New Mexico.

In his writing, Leopold left behind lucid observations of the natural world, gleaned mainly from the time that he and his family spent at a weekend refuge, a "sand farm" in Wisconsin, and driven by his burning desire to preserve that world. Leopold made no attempt to mask his prime motivation in working for conservation: Wilderness, unadulterated by humans, is worth preserving for its own sake. He found no need to muster economic benefits from wildlife preserves; in fact, he wrote from many angles about why such arguments did not apply.

In "Goose Music," for example, he wrote:

"If wild birds and animals are a social asset, how much of an asset are they? ... In short, what is a wild goose worth? ... Worth in dollars is only an exchange value, like the sale value of a painting or the copyright of a poem. What about the replacement value? Supposing there were no longer any painting, or poetry, or goose music? It is a black thought to dwell upon, but it must be answered. In dire necessity somebody might write another Iliad, or paint an 'Angelus,' but fashion a goose?"

Ever honest, Leopold went on to identify the source of his passion for wild beasts as "congenital hunting fever" and wondered how his three sons would fare if there were:

"No more snipe whistling in the meadow, no more piping of widgeons and chattering of teal as darkness covers the marshes; no more whistling of swift wings when the morning star pales in the east? And when the dawn-wind stirs through the ancient cottonwoods, and the gray light steals down from the hills over the old river sliding softly past its wide brown sandbars--what if there be no more goose music?"