Wherever or whatever the shaman enters, first in dream and then in reality, whether his own or ours or both, what matters is the otherworldliness of the journey. The shaman travels to heal illness, sometimes of a single person, sometimes of a tribe, yet the healing can be accomplished only after the shaman himself has known the illness, whether derangement or dismemberment. Central to shamanism are its supposed mysteries: flight, levitation, gender transformation, bilocation, and animal and bird incarnations.
— Harold Bloom, Omens of Millennium