The foot is the symbol of your creative power, and to tread a place is to occupy a state in imagination until it feels solid underfoot. Whatever state a person walks into that way becomes his own, from the barren stretches to the far shore, because nothing he vividly enters and stands within stays outside his reach.
The wilderness and the uttermost sea mark the whole range, the empty and the distant alike, all of it claimed the moment the feeling of being there becomes real. The world of mere reported fact is the flood you rise up out of by this act. So the possessing is done within before it shows without. In plain words, a scene held until it feels like where you actually are is a scene you will end up living in, and there is no ground closed to that kind of walking.