Hudson River School paintings reflect three themes of America in the 19th century: discovery, exploration, and settlement. The paintings also depict the American landscape as a pastoral setting, where human beings and nature coexist peacefully. Hudson River School landscapes are characterized by their realistic, detailed, and sometimes idealized portrayal of nature, often juxtaposing peaceful agriculture and the remaining wilderness, which was fast disappearing from the Hudson Valley just as it was coming to be appreciated for its qualities of ruggedness and sublimity. In general, Hudson River School artists believed that nature in the form of the American landscape was an ineffable manifestation of God, though the artists varied in the depth of their religious conviction. They took as their inspiration such European masters as Claude Lorrain, John Constable and J. M. W. Turner. Their reverence for America's natural beauty was shared with contemporary American writers such as Henry David Thoreau and Ralph Waldo Emerson. Several painters were members of the Düsseldorf school of painting, others were educated by the German Paul Weber.