During the three centuries of Tibet’s modern period, the national priority was on monastic education, literary and philosophical creativity, the practice of meditation, the development of ritual and festival arts, and so forth. Spiritual adepts were accepted as the highest level of Tibetan society, considered to have become perfected [awakened beings] through their practice of the Tantras (spiritual technologies) of Unexcelled Yoga (self-cultivation). They were inner-world adventurers of the highest daring, the Tibetan equivalent of our astronauts — I think it is worth coining the term “psychonaut” to describe them. They personally voyaged to the furthest frontiers of that universe which their society deemed vital to explore: the inner frontiers of consciousness itself, in all its transformations in life
and beyond death.
In Western culture, the last frontiers of our material conquest of the universe are outer space. Our astronauts are our ultimate heroes and heroines. Tibetans, however, are more concerned about the spiritual conquest of the inner universe . . .
Robert Thurman
from a forward to The Tibetan Book of the Dead