 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.
