"Caspar David Friedrich (1774–1840), the greatest painter of the Romantic movement in Germany, was perhaps Europe’s first truly modern artist. His melancholy landscapes, often peopled by lonely wanderers, represent experiments towards a radically subjective art, one in which, as Friedrich wrote, the painter depicts not ‘what he sees before him, but what he sees within him.’ Yet in their awesome power to capture the individuality of visible forms Friedrich’s pictures also accept and express the irredeemable otherness of Nature. "

Joseph Leo Koerner (2009) "Caspar David Friedrich and the Subject of Landscape" (Reaktion)