People usually declare that landscape is an easy matter. I think it a
very difficult one. For whenever you wish to produce a landscape, it is
necessary to carry about the details, and work them out in the mind for
some days before the brush may be applied. Just as in composition: there
is a period of bitter thought over the theme; and until this is
resolved, you are in the thrall of bonds and gyves. But when inspiration
comes, you break loose and are free.
_A Chinese Painter_ (about 1310 A.D.).