They traveled along walkways where the light was soft and yellow. Hummin’s eyes moved this way and that, watchful, and he kept their pace at crowd speed, neither passing nor being passed.

He kept up a mild but steady conversation on indifferent topics.

Seldon, edgy and unable to do the same, said, “There seems to be a great deal of walking here. There are endless lines in both directions and along the crossovers.”

“Why not?” said Hummin. “Walking is still the best form of short-distance transportation. It’s the most convenient, the cheapest, and the most healthful. Countless years of technological advance have not changed that. —Are you acrophobic, Seldon?”

Seldon looked over the railing on his right into a deep declivity that separated the two walking lanes—each in an opposite direction between the regularly spaced crossovers. He shuddered slightly. “If you mean fear of heights, not ordinarily. Still, looking down isn’t pleasant. How far does it go down?”

“Forty or fifty levels at this point, I think. This sort of thing is common in the Imperial Sector and a few other highly developed regions. In most places, one walks at what might be considered ground level.”

“I should imagine this would encourage suicide attempts.”

“Not often. There are far easier methods. Besides, suicide is not a matter of social obloquy on Trantor. One can end one’s life by various recognized methods in centers that exist for the purpose—if one is willing to go through some psychotherapy at first. There are occasional accidents, for that matter, but that’s not why I was asking about acrophobia. We’re heading for a taxi rental where they know me as a journalist. I’ve done favors for them occasionally and sometimes they do favors for me in return. They’ll forget to record me and won’t notice that I have a companion. Of course, I’ll have to pay a premium and, again of course, if Demerzel’s people lean on them hard enough, they’ll have to tell the truth and put it down to slovenly accounting, but that may take considerable time.”

“Where does the acrophobia come in?”

“Well, we can get there a lot faster if we use a gravitic lift. Not many people use it and I must tell you that I’m not overjoyed at the idea myself, but if you think you can handle it, we had better.”

“What’s a gravitic lift?”

“It’s experimental. The time may come when it will be widespread over Trantor, provided it becomes psychologically acceptable—or can be made so to enough people. Then, maybe, it will spread to other worlds too. It’s an elevator shaft without an elevator cab, so to speak. We just step into empty space and drop slowly—or rise slowly—under the influence of antigravity. It’s about the only application of antigravity that’s been established so far, largely because it’s the simplest possible application.”

“What happens if the power blinks out while we’re in transit?”

“Exactly what you would think. We fall and—unless we’re quite near the bottom