There's some similarity between trees and human figures in the way that exhortation, coercion and disruption operate. The weightlessness of human form (when it's attractive?) may have something to do with this. Which raises the question about weight and lightness. Of course the issue is not what things are, but the effect they have on the perceiver. In looking, I am regulating myself. As I stand at the root and look at the branches, I am regulating myself. It is my need for coercion, disruption and exhortation... not the thing in the tree. But I find the things that address these issues. The same may be true of looking at people.