“That’s because of the computer, isn’t it?” came another, deeper female voice, that of the stocky girl from the heavy-gravity world whose family name was Marino.

“Yes,” Skander agreed. “But, come, let’s move into the city. We can talk as we go.”

They started forward, soon coming into a broad boulevard, perhaps fifty meters across. Along each side ran what appeared to be broad walkways, each six to eight meters across, like the moving walkways of spaceports that took you to and from loading gates. But no conveyor belt or such was evident; the walkways were made of the same greenish-brown stone, or metal, or whatever it was that composed the rest of the city.

“The crust of this planet,” Skander continued, “is about average—forty to forty-five kilometers thick. Measurements on this and other worlds of the Markovians showed a consistent discontinuity, about one kilometer thick, between the crust and the natural mantlerock beneath. This, we have discovered, was an artificial layer of material that is essentially plastic but seems to have had a sort of life in it—this much, at least, we infer. Consider how much information your own cells contain. You are the products of the best genetic manipulation techniques, perfect physical and mental specimens of the best of your races adapted to your native planets. And yet, for all that, you are far more than the sum of your parts. Your cells, particularly your brain cells, store input at an astonishing and continuing rate. We believe that this computer beneath your feet was composed of infinitely complex artificial brain cells. Imagine that! It runs the entirety of the planet, a kilometer thick—all brain. And all, we believe, attuned to the individual brain waves of the inhabitants of this city!