Here is an excerpt (scanned):
"Do you have a theory,"
"Several. But explanations of each of them would take more time than we have."
"Please share with us the theory that you believe most likely. "
"The saucer is man-made."
"You mean people like us?"
"I mean our ancestors."
A murmur ran through the airport crowd that was watching this with Rip. He looked around at the people there, white, black, Hispanic, Asian, some of indeterminate race. All of them were listening intently to Professor Soldi.
"Civilizations don't just happen," the professor explained. "Hunter-gathering Stone Age societies are at one end of the continuum, we are somewhere closer to the other end. Each technological level, if you will, above Stone Age hunter gatherers requires a different level of social organization to support it. Increased specialization is the rule. The industrial age required millions of workers and consumers. The postindustrial age required even more specialization, a larger base of workers and consumers. We are now moving into the era of the global economy, in which the brains, talents, and skills of workers all over the planet will be melded together in gigantic enterprises to create further technical progress. Our destination is the technological future that created the saucer."
"I think I understand," the interviewer prompted.
"The properties of the technological continuum that we have just talked about are rigid; in effect, they are laws. Since each level of technological achievement requires more and more people, more and more social organization, it follows that without the specialized people, the technological level cannot be sustained."
"Keep going," the interviewer said.
"A society that can build a device like the saucer, put it in an interplanetary spaceship, and cross the vastness of interstellar space will not be able to replicate that society any~where else unless they bring their whole population, or most Of it. Upon arrival at the planet they intended to colonize, the small number of people who could make that voyage would drop to a technological level that they could sustain."
"You are saying that if the saucer brought colonists, they became hunter-gatherers to survive."
"Precisely," said Professor Soldi. "Spaceships, computers, tools, weapons, lasers, advanced medical devices, books, learning-they lost everything. There weren't enough people to maintain or manufacture any of that. The abandoned saucer was finally covered with sand by the wind. The people lived in caves and learned to make tools with stone and ate their meat raw. The past was passed on as legends and myths. Eventually over the generations the legends and myths became unrecognizable, completely divorced from historical fact. The past was lost, just as the saucer had been."