Some five hundred years before, the people of Pura had discovered the basic art of stimulating the senses by using direct brain-computer links. Blade wondered if in the process of discovering this art and learning to control it, they had sent any unsuspecting subjects off into other dimensions. But they had learned to control the linkages bit by bit, and that had been the foundation for Pura's greatest-and last-achievement.

About two hundred years before, they had discovered the methods of recording and simulating specific sets of sensations. Soon it became possible to put these sensations together into complete stories, which were incredibly complex and totally realistic as long as one was hooked up. They could satisfy any possible or impossible fantasy that one could harbor in one's waking mind.

But even then Pura was not doomed. No matter how much of one's sleeping hours one spent Dreaming, one still had to spend a certain amount of time awake for eating, washing, exercising, and generally carrying out the necessary business of staying alive. Even those wealthy enough not to need jobs could not spend all their time Dreaming.

Then somebody invented the life-sustaining gas and all the life-support equipment that went with it. It became possible to spend years on end in the Dreams; the periods of Waking were reduced to only a few days to «test» one's body for signs of physical deterioration.

Within a few years everybody was working just enough to be able to spend the rest of the time Dreaming. A man would work six months, then go to a public Dream House, climb into a vault, and for the next six months be a wandering minstrel or knight from the city's ancient history or travel among the stars as one might in the far future. The only people who had to work all the time were the Dream-builders, who developed and recorded new Dreams, the vault masters, who, prepared the vaults, and the life-support technicians, who maintained and improved the machinery that kept the Dreamers alive and healthy.