The book was said to have been composed by the Indian yogi Padmasambhava, who is credited with introducing Buddhism into Tibet in the eighth century and regarded as the founding father of the esoteric tradition. Like hundreds of his teachings, the text was supposedly transcribed in a cryptic language and secreted as a "treasure text", to be discovered at a time when it was appropriate to be transmitted to the general populace. It was found, in the 12th century, hidden in a mountain in Tibet by a "treasure seeker" known as Karma Lingpa, who deciphered the cryptic text and passed on the teaching orally to his son. It was several generations before it was finally written down, becoming one of the central teachings in the Tibetan Buddhist canon.

The first English translation appeared in 1927, edited by an American Theosophist named Walter Evans-Wentz, who came across the text while travelling in India. It had been given to him by a British army officer who had recently returned from Tibet. Evans-Wentz commissioned a translation from a Tibetan who taught English at a boys' school, and published it as The Tibetan Book of the Dead.

In fact, Evans-Wentz had stumbled upon only a small portion of the original text - the so-called "Great Liberation by Hearing", a teaching designed to be committed to memory by the dying person, or read to them after death to guide them on the hazardous journey through the after-death state. But it was this small fragment that would form the basis for the innumerable translations and adaptations that have appeared since.

Coleman is the president of the Orient Foundation, the editor of several books and the director of a film trilogy about Tibetan Buddhism and culture. In 1989 he approached the Dalai Lama seeking his help in executing the first complete English translation of the Book of the Dead. The Dalai Lama arranged for Dilgo Khyentse Rinpoche, head of the school from which the original text derives, to give Coleman a full oral teaching, as it would have been transmitted originally. Over the next 16 years, another scholar, Gyurme Dorje, worked on a new translation of the text, which Coleman refined and edited with the help of the Dalai Lama's senior translator, Thupten Jinpa.

This extraordinary journey has lent itself to myriad interpretations. Evans-Wentz saw it as proof of the theories of reincarnation espoused by the founder of Theosophy, Madame Blavatsky (which had themselves been borrowed from Tibetan Buddhism).

Carl Jung, who claimed that the Evans-Wentz translation rarely left his side, saw the book as evidence for his theories on the collective unconscious. He likened the mutilations inflicted by the demon Yama to the dissociative states of schizophrenia, and suggested that the book should be read back to front - from rebirth to death - as a parallel to the model process of psychoanalysis. Timothy Leary, in his book The Psychedelic Experience: A Manual Based on the Tibetan Book of the Dead (1964) saw the Tibetan text as a metaphor and guide for the LSD trip.

More recently, the Tibetan lama Sogyal Rinpoche used the Book of the Dead as the basis for his sweetened Buddhist primer, The Tibetan Book of Living and Dying, which has sold more than two million copies. Fearful, perhaps of his readers bridling at a literal belief in "the six realms" of existence, Sogyal prefers to render them as different aspects of the human condition - locating the "god realms" in California and seeing the "anguished spirits" as capitalist barons, never satisfied no matter much wealth they accumulate.