Druids Trees: The #Tree of #Life is derived from old Celtic customs. Forests of the Old World were vast, covering whole countries. When a tribe cleared land for a settlement, they always left one tree in the center. This was called in Irish "Crann Bethadh" ("Tree of Life"). Trees touch all three realms of existence---the Overworld with branches, the Underworld or spirit world with roots, and the mortal world with trunks.