Aldo Leopold
A Sand County Almanac Leopold wrote A Sand County Almanac (hardcover ISBN 0-19-505305-2, paperback ISBN 0195007778), which has been read by millions and has informed and changed the environmental movement and a widespread interest in ecology as a science. By the same token, the Wilderness Society and LeopoldÕs work in it were important precursors to the environmental movement that coalesced around the time of the first Earth Day. Published in 1949, shortly after Leopold's death, A Sand County Almanac is a combination of natural history, scene painting with words, and philosophy. It is perhaps best known for the following quote, which defines his land ethic: "A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community. It is wrong when it tends otherwise.Ó

Conservation: In "The Land Ethic," a chapter of A Sand County Almanac, Leopold delves into conservation in "The Ecological Conscience" section. He wrote: "Conservation is a state of harmony between men and land."