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Landscape and the sublime

What the newer landscape artists see in a circle of a hundred degrees in Nature they press together unmercifully into an angle of vision of only forty-five degrees. And furthermore, what is in Nature separated by large spaces, is compressed into a cramped space and overfills and oversatiates the eye, creating an unfavorable and disquieting effect on the viewer.

The visualisation and portrayal of landscape in an entirely new manner was Friedrich's key innovation. He sought not just to explore the blissful enjoyment of a beautiful view, as in the classic conception, but rather to examine an instant of sublimity, a reunion with the spiritual self through the contemplation of nature. Friedrich was instrumental in transforming landscape in art from a backdrop subordinated to human drama to a self-contained emotive subject. Friedrich's paintings commonly employed the Rückenfigur —a person seen from behind, contemplating the view. The viewer is encouraged to place himself in the position of the Rückenfigur, by which means he experiences the sublime potential of nature, understanding that the scene is as perceived and idealised by a human.

Friedrich created the idea of a landscape full of romantic feeling— die romantische Stimmungslandschaft. His art details a wide range of geographical features, such as rock coasts, forests and mountain scenes, and often used landscape to express religious themes. During his time, most of the best-known paintings were viewed as expressions of a religious mysticism. He wrote: "The artist should paint not only what he sees before him, but also what he sees within him. If, however, he sees nothing within him, then he should also refrain from painting that which he sees before him. Otherwise, his pictures will be like those folding screens behind which one expects to find only the sick or the dead." Expansive skies, storms, mist, forests, ruins and crosses bearing witness to the presence of God are frequent elements in Friedrich's landscapes. Though death finds symbolic expression in boats that move away from shore—a Charon -like motif—and in the poplar tree, it is referenced more directly in paintings like The Abbey in the Oakwood (1808–1810), in which monks carry a coffin past an open grave, toward a cross, and through the portal of a church in ruins.

He was one of the first artists to portray winter landscapes in which the land is rendered as stark and dead. Friedrich's winter scenes are solemn and still—according to the art historian Hermann Beenken, Friedrich painted winter scenes in which "no man has yet set his foot. The theme of nearly all the older winter pictures had been less winter itself than life in winter. In the 16th and 17th centuries, it was thought impossible to leave out such motifs as the crowd of skaters, the wanderer... It was Friedrich who first felt the wholly detached and distinctive features of a natural life. Instead of many tones, he sought the one; and so, in his landscape, he subordinated the composite chord into one single basic note".

Bare oak trees and tree stumps, such as those in Raven Tree (c. 1822), Man and Woman Contemplating the Moon (c. 1824), and Willow Bush under a Setting Sun (c. 1835), are recurring elements of his paintings, and usually symbolise death. Countering the sense of despair are Friedrich's symbols for redemption: the cross and the clearing sky promise eternal life, and the slender moon suggests hope and the growing closeness of Christ. In his paintings of the sea, anchors often appear on the shore, also indicating a spiritual hope. In The Abbey in the Oakwood, the movement of the monks away from the open grave and toward the cross and the horizon imparts Friedrich's message that the final destination of man's life lies beyond the grave.

With dawn and dusk constituting prominent themes of his landscapes, Friedrich's own later years were characterised by a growing pessimism. His work becomes darker, revealing a fearsome monumentality. The Wreck of the Hope —also known as The Polar Sea or The Sea of Ice (1823–1824)—perhaps best summarises Friedrich's ideas and aims at this point, though in such a radical way that the painting was not well received. Completed in 1824, it depicted a grim subject, a shipwreck in the Arctic Ocean; "the image he produced, with its grinding slabs of travertine -colored floe ice chewing up a wooden ship, goes beyond documentary into allegory: the frail bark of human aspiration crushed by the world's immense and glacial indifference."

Friedrich's written commentary on aesthetics was limited to a collection of aphorisms set down in 1830, in which he explained the need for the artist to match natural observation with an introspective scrutiny of his own personality. His best-known remark advises the artist to "close your bodily eye so that you may see your picture first with the spiritual eye. Then bring to the light of day that which you have seen in the darkness so that it may react upon others from the outside inwards."