The air taken in and sent out that one feels through the nostrils or lungs is what we ordinarily call breath. In reality, however, that is as the stem of a tree whose branches are many. According to the physician the lungs are the channel of the breath, but to the mystic the lungs are the branches of the tree, and other branches reach all parts of the body. This tree has a root in the body, and has centers where the branches meet the stem.