What is the name of the person who wanted people to understand that the scene is as perceived and idealised by a human?
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 notion 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.  He often used the landscape to express religious themes. During his time, most of the best-known paintings were viewed as expressions of a religious mysticism.
Friedrich said, "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 (1808–10), 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".
Friedrich