The birch forests of Ásbyrgi are not passable, except slowly and in no direction not directed by the trees.
The words for human bodies come from trees like this: body, belly, bone, arm, branch, and so on. Only after these properties were named were the names applied to humans. Before that, our ancestors saw only the trees. In that sense, we are the hidden people, just as much as we are the boughs, beams, trunks and bodies reaching here.