Monadnock, which comes originally from the Abnacki Native American word for mountain that stands alone, is now a standard geological term for any singular mountain that rises above the surrounding plain. This area has a rich cultural history and a tradition of providing inspiration for the works of Henry David Thoreau, Ralph Waldo Emerson, Mark Twain, and Abbott Thayer. The Society for the Protection of New Hampshire Forests, the state's oldest non-profit conservation organization, founded in 1901, is the major landowner on Mt. Monadnock. It holds more than 3,500 acres in the public interest. The Monadnock acquisition program, begun in 1910, is still continuing. Lands on Monadnock are leased to the state for management purposes.