Seven generation sustainability
Seven generation sustainability is an ecological concept that urges the current generation of humans to live sustainably and work for the benefit of the seventh generation into the future. It originated with the Iroquois - Great Law of the Iroquois - which holds appropriate to think seven generations ahead (about 140 years into the future) and decide whether the decisions they make today would benefit their children seven generations into the future.
"In every deliberation, we must consider the impact on the seventh generation... even if it requires having skin as thick as the bark of a pine." This is an often repeated saying, and most who use it claim that it comes from “The Constitution of the Iroquois Nations: The Great Binding Law.”
In fact, the original language is as follows: In all of your deliberations in the Confederate Council, in your efforts at law making, in all your official acts, self-interest shall be cast into oblivion. Cast not over your shoulder behind you the warnings of the nephews and nieces should they chide you for any error or wrong you may do, but return to the way of the Great Law which is just and right. Look and listen for the welfare of the whole people and have always in view not only the present but also the coming generations, even those whose faces are yet beneath the surface of the ground – the unborn of the future Nation.
Oren Lyons, Chief of the Onondaga Nation, writes: "We are looking ahead , as is one of the first mandates given us as chiefs, to make sure and to make every decision that we make relate to the welfare and well-being of the seventh generation to come. . . ." "What about the seventh generation? Where are you taking them? What will they have?" 
- An Iroquois Perspective. Pp. 173, 174 in American Indian Environments: Ecological Issues in Native American History. Vecsey C, Venables RW (Editors). Syracuse University Press, New York.