Also called "Bardo Thodol." Actually entitled, "The Great Book of Natural Liberation through Understanding in the Between." One of many Tibetan texts intended to be read to the dead or dying person, and which provides guidance to pass consciously through varying states of being.
"The Bardo Thodol, the Tibetan book that talks about the spirits of the world of the afterlife, stands out magnificently before our eyes, letting us see the crude reality of the infernal worlds located within the interior of this planetary organism on which we live." - Samael Aun Weor, The Three Mountains