In 1949 A Sand County Almanac by American ecologist, forester, and environmentalist Aldo Leopold was published in New York one year after Leopold's death. A combination of natural history, philosophy, and poetic writing, it informed the environmental movement. "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.' The concept of a trophic cascade is put forth in the chapter Thinking Like a Mountain, wherein Leopold realizes that killing a predator wolf carries serious implications for the rest of the ecosystem" (Wikipedia article on Aldo Leopold, accessed 01-18-2209).