At the start of the nineteenth century Romanticism arose as a reaction to the cold reason of the Enlightenment: feeling, infinity, the terrifying grandeur of nature, and the inner world of the individual came to the fore. The German painter Caspar David Friedrich (1774–1840) gave this mood its deepest visual expression.

"Wanderer above the Sea of Fog" was painted around 1818. A man stands atop a rocky outcrop, his back to us; before him stretches a vast mountain landscape veiled in fog. Friedrich's most famous device is this "figure from behind" (Rückenfigur): we cannot see the man's face, because we are meant to see what he sees, to look at the landscape together with him. The viewer identifies with the person within the painting; the landscape becomes not an external view but an inner experience.

This is the feeling that eighteenth-century aesthetics called the "sublime" (das Erhabene): unlike the calm of the beautiful, that sense of grandeur which both overwhelms and elevates, uniting fear with wonder. Friedrich's mountains, mists, and vast skies present nature not as a backdrop but as a presence before which the human feels both his own finitude and a longing for the infinite. His landscapes often carry a religious silence — nature itself, rather than a church, is a temple.

Friedrich's influence is not obvious but is deep: he is the forerunner of the "inner landscape" tradition running from Symbolism to Expressionism and even to modern landscape and photography. What nature dissolved in light is to Turner, nature wrapped in fog is to Friedrich: one of the two great wings by which the nineteenth century carried painting from the record of the outer world to the expression of the inner.