The green movement has been influenced by left-libertarian traditions, including anarchism, mutualism, Georgism and individualist anarchism. Peter Kropotkin provided a scientific explanation of how mutual aid is the real basis for social organization in his "Mutual Aid: A Factor in Evolution". New England transcendentalism (especially Henry David Thoreau and Amos Bronson Alcott) and German Romanticism, the pre-Raphaelites and other back to nature movements combined with anti-war, anti-industrialism, civil liberties and decentralization movements are all part of this tradition. In the modern period, Murray Bookchin and the Institute for Social Ecology elaborated these ideas more systematically. Bookchin was one of the main influences behind the formation of the Alliance 90/The Greens, the first green party to win seats in state and national parliaments. Modern green parties attempt to apply these ideas to a more pragmatic system of democratic governance as opposed to contemporary individualist or socialist libertarianism. The green movement, especially its more left-wing factions, is often described by political scientists as left-libertarian.