Description of this motif: Yggdrasil or Ygdrasil is the great ash tree at the center of the world in Norse mythology. Its three roots are rooted in respectively the world of death, the giants and mankind. At the tree are also three wells. Odin threw his one eye in one of them, Mimer's well, in order to achieve wisdom. Yggdrasil means Odin's (Ygg's) horse, referring to a myth, that says that Odin once "rode" it, i.e. hang in its branches, letting himself be swayed by the wind. See Gads religionsleksikon, 1999.
Under Ygdrasil tree the gods sat every day;
But the tree is dead and the gods have gone away.