anyone or anything suspended on the axis between heaven and earth becomes a repository of potential knowledge. a special status accrues to the thing suspended: a serpent, a victim of crucifixion or hanging, a rod, a fruit, mistletoe. derivations of this idea find form in the rod of asclepius, an emblem of the medical profession, and in the caduceus, an emblem of correspondence and commercial professions. the staff in these emblems represents the axis mundi while the serpents act as guardians of, or guides to, knowledge.