The artists of the Hudson River School, such as Thomas Cole, Asher B. Durand, Frederic Edwin Church, and Albert Bierstadt, were American artists interested in establishing an American tradition separate from the influences of European art. The work of this informal group was certainly initially inspired by Romanticism and European landscapes, but demonstrated a certain realism, and was philosophically tied to transcendentalism as expressed by the American philosophers Ralph Waldo Emerson and Henry David Thoreau. Through open air, or plein air, painting, which required significant hiking and traveling to locations that reached from the Catskills to Niagara Falls to Yosemite Valley, the artists of the Hudson River School depicted an apparent untouched Eden that juxtaposed sweetly pastoral scenes with the power of the American wilderness.