Brief History of Everything - Ken Wilber

Wilber tries to describe the evolution of consciousness. In Wilber's definition, the spirit is above the mental. It is divided into several levels, the lowest is called the psychic level. This is the level that shamans normally travel in. Wilber uses Ralph Waldo Emerson's Over-Soul as the motivator for a discussion of the psychic interconnections between all of Nature. It seems that Redfield is trying to help his readers gain knowledge of this realm.