dle of a once useless dial rose and fell.

"What's the matter with the poor dear?" asked Anti. "She's shaking."

"Let her alone," said Docchi.

No one moved. No one said anything at all. Minutes passed while the
ancient ship creaked and groaned and ran away from the fastest rockets
in the Solar System.

"I think I know," said Docchi at last, still frowning. "Consider the
gravity-generating plant. Part of it is an electronic computer,
capable of making the necessary calculations and juggling the
proportion of power required to produce, continuously, directed or
undirected gravity. In other words, a brain, a complex mechanical
intelligence. From the viewpoint of that intelligence, why should it
perform _ad infinitum_ a complicated but meaningless routine? It
didn't know why, and because it didn't, very simply, it refused to do
so.

"Now consider Nona. She's deaf, can't speak, can't communicate. In a
way she's comparable to the gravital computer. Like it, she has a very
high potential intelligence. Like it, she's had difficulty grasping
the facts of her environment. Unlike it, though, she has learned
something. How much, I don't know, but it's far more than the
Medicouncil psychologists credit her with."

"Yeah," said Jordan dubiously. "But what's happening now?"

"If there were two humans involved, you would call it telepathy,"
answered Docchi hesitantly, fumbling for concepts he could only sense
without grasping. "One intelligence is electronic, the other organic.
You'll have to coin a new term, because the only one I know is
extrasensory perception, and that's obviously ridiculous. It is, isn't
it?"

Jordan smiled and flexed his arms. Under the shapeless garment his
muscles rippled. "It isn't," he said. "The power was there, but we're
the only ones who know how to use it. Or rather Nona is."

"Power?" repeated Anti, rising majestically. "You can keep it. I want
just enough to get to Centauri."

"I think you'll get it," Docchi promised. "A lot of things seem
clearer now. For example, in the past, why didn't gravital units work
well at considerable distances from the Sun? As a matter of fact, the
efficiency of each unit was inversely proportional to the square of
the distance between it and the Sun.

"The gravital computer is a deaf, blind, mass-sensitive brain. The
major fact in its existence is the Sun, the greatest mass in the Solar
System. To such a brain, leaving the Solar System would be like
stepping