Henry David Thoreau, the philosopher of Walden Pond who gave early voice to environmental awareness, said: "Nature will bear the closest inspection. She invites us to lay our eye level with her smallest leaf, and take an insect view of its plain."

But how do we accept that invitation in a spreading world of concrete and glass that every day claims the remaining quiet and wild places? With one piece of property saved at a time. With one organization at a time dedicated to conserving such land.

In our corner of the world, that noble work is being done by the Western Pennsylvania Conservancy, which this year celebrates its 75th anniversary.

Since 1932, the conservancy has protected nearly 225,000 acres for future generations. Most of the land has become publicly owned, adding to the size of state parks and game lands and becoming a source of enjoyment to millions of people. Indeed, the conservancy estimates that it has protected nearly half of all the land protected by land trusts in Pennsylvania.

It also works at the local level. Last year, it helped 5,000 volunteers and dozens of community groups in 19 Western Pennsylvania counties to plant 140 gardens. Additionally, it preserves architect Frank Lloyd Wright's masterwork, Fallingwater, which gracefully straddles Bear Run in Fayette County.

To commemorate its milestone, the conservancy has announced its "75th Anniversary Acquisitions," the first stage being 6,050 acres in Western Pennsylvania bought for permanent preservation in one of the most scenic areas of the state. The purchases came about through a grant of nearly $8 million from the Richard King Mellon Foundation and $4.5 million from the Pennsylvania Department of Conservation and Natural Resources.

The Laurel Creek Forest tract is 2,300 acres in Somerset County that will become part of Forbes State Forest. The Southern Clarion River Forest is 3,300 acres (1,600 acres of land and 1,700 acres of timber rights) along the Clarion River south of Cooksburg; it will become part of Clear Creek State Forest. In addition, 450 acres in Jefferson and Forest counties have been preserved.

Then Wednesday, the conservancy announced the second phase of its anniversary acquisitions, the purchase of 5,340 acres of scenic hardwood forest in Clearfield and Elk counties that it named the Bennett Branch Forest. The Richard King Mellon Foundation provided $6 million and the DCNR $2 million. The land will be added to Moshannon State Forest.

In its 75th year, the Western Pennsylvania Conservancy deserves the region's thanks for work that has an importance Thoreau would have understood.