Shamanic Wisdom and the Pyramid Texts offers a compelling and coherent explanation of how most (and perhaps all) of the pyramid-temple complexes in ancient Egypt were used. Naydler bases his argument primarily on the content of the texts at the pyramid of Unas, which has the most complete surviving set of ritual descriptions. The more famous pyramid complex at Giza was built 180 years later, but its inscriptions apparently were carved on the outer stone casings, which have been stripped away and lost. Naydler speculates that those inscriptions would have told much the same story.
Unlike many traditional Egyptologists, Naydler believes that the pyramid ritual describes, not primarily burial rites, but the festival of Sed. This festival was to occur every thirty years during a king's reign. During the ritual and guided by priests, the king underwent a spiritual process of death, dismemberment, reintegration, and rebirth. This is a shamanic, astral journey which empowers the king with benefits that ensure the welfare of the entire kingdom. It also makes it possible for him to reascend, as shamans do, to communicate with the higher realms at will. The process of death and transformation follows the path of the Osiris myth, in which Osiris dies (at the hands of the evil Seth) and is dismembered. His consort Isis searches for his parts, mates with his severed organ, and gives birth to a reintegrated Osiris as her son Horus. In the Sed ritual, the king enters the rite as Osiris and emerges as the living Horus, ready to resume his earthly reign. This is the same cycle the dead king will follow to achieve rebirth in the astral realm (which is the traditional academic view).
My only complaint with the book is that Naydler feels he has to spend so much time contending with the prejudices of traditional Egyptology. He is primarily a historian of religion, sympathetic with the world view of Mircea Eliade, and his approach deals more directly with the content of the texts than their social and cultural contexts. He warns the reader that the book was intended mainly as a doctoral thesis, and it certainly reads that way. A more popular text could have simply taken a position and not done so much self-justification. Anyone interested in this subject, no matter what the academic field, should pay attention to this significant book.