Who is Ambres from Out on a Limb and what is their importance?

Ambres is the spirit that Sture Johanssen channels. Ambres speaks in an ancient form of Swedish. When Shirley meets Ambres, she is struck by how different his voice is from Sture's voice. Ambres speaks about spirituality and the creation of life when Shirley is in his presence, causing her to be overwhelmed by his knowledge and convinced that Sture cannot be faking Ambres' presence.