Healer and psychopomp, the shaman is these because he commands the techniques of ecstasy—that is, because his soul can safely abandon his body and roam at vast distances, can penetrate the underworld and rise to the sky. Through his own ecstatic experience he knows the roads of the extraterrestrial regions. He can go below and above because he has already been there.

Shamanism: Archaic Techniques of Ecstasy (1951)