[The] plunge into the twilight of the psyche obliterates the normal categories of perception, replacing them with a vision that is unique and personal. The shamanic candidate, led by elders, encounters spirits that are part animal and part human, men dressed as women and vice versa, and monstrous shapes and forms that represent the ambiguous forces of the universe that are frightening to the human ego. From that moment on, the universe will be wider and grander, more mysterious, and yet (and this is the point of being a shaman) more manageable. The old social boundaries and mental constructs that the new shaman formerly accepted as immovable and inviolable are revealed to be socially conditioned, arbitrary structures. Like a mask, the everyday world of family and clan conceals amorphous realms of spirit, nature, beauty, and terror that defy categorization. And during the perils of initiation, the new shaman learns how to remove this mask.
The shaman develops a fluid, malleable worldview that is not as brittle as most people’s. Shamans know that the real and the unreal are merely opposite ends of a continuum on which reality can be stretched to include what is normally considered unreal. Even better, the continuum, like a flexible rod, can be bent, curved, and shaped into a circle where the end points of reality and unreality meet and become the same point. To the shaman, the universe is truly the Uroborous, the serpent holding its own tail in its mouth, uniting what appears to be the beginning and end. Depending on your point of view, the serpent is either devouring or disgorging the universe of its own body. To the shaman, it may appear to be doing both at once; and the shaman is not confused by this.
The shamanic initiation is a journey into chaos, a plunge into the primal realm where things are not what they seem, where rules and guidelines governing conduct and belief fail and are no longer appropriate. The shaman-to-be is initially terrified of what appear to be hostile spirits, even while being conducted safely through the ordeal by friendly spirits who may appear as ancestors or animal powers. In the process, shamans acquire a new self. Their mental universe is unraveled and rewoven, their physical bodies are dismembered and reintegrated or replaced with spiritual bodies. Finally the shaman re-enters ordinary reality as a “wise woman” or a “man of knowledge,” an interpreter of the spirit world, one who has seen reality demolished and reconstructed. The shaman begins to understand the ambiguous nature of the universe and the unending law of change by which it operates.
— Tom Cowan, Fire in the Head, pp. 51-52