street. Gool
touched a button, and the car shot ahead at high speed along the
overhead mono-rail. The old man, who had settled comfortably back on one
of the upholstered seats, was faintly smiling as he watched Gerry's
face.

"You are puzzled, stranger?" he asked at last.

"Yes. There seemed to be nothing on the plain but a lot of holes bored
in the rock, and now...."

"And now you find yourself in the city of Moorn," Gool said. "A
knowledge of dimensional control is one of the reasons why we of this
city have lived in peace and safety for so many centuries while the rest
of the planet is torn by constant wars."

"Dimensional control?" Gerry said slowly. Gool nodded.

"Yes. It is hard to put it into language that will be clear to one who
has no knowledge of our science. Perhaps I can explain it by saying that
the human eye is a three-dimensional organism, and therefore capable of
perceiving only things that fall into that same category. There are a
great many things in the universe, some of the greatest importance, that
the ordinary man's senses are incapable of perceiving. We have learned
how to cast a protective screen of fourth-dimension rays about our city,
and the effect is that it becomes completely invisible to the human eye.
Do I make myself clear?"

"Not entirely," Gerry grinned. "But I do know that your screen works!
But, since your science is so far ahead of the other people of Venus,
why don't you rule the entire planet?"

"The other races are all barbarians," Gool said with a sort of
disdainful gravity. "We prefer to live here in our peaceful isolation
and not bother with them. That is an essential part of our philosophy."

The speeding mono-rail car mounted higher as it neared the center of the
city. The track seemed to end on the blank wall halfway up the tallest
of the buildings, but as the car came near a circular doorway suddenly
opened just in time to let it through. They halted in a circular chamber
where heavy springs caught and allayed the last of the car's momentum,
and a pair of gold-helmeted guards saluted Gool as they helped him to
alight.

"The Council is ready and waiting, my Lord," said one. Gool nodded over
his shoulder to Gerry.

"Follow me," he commanded.

The Council of Elders of Moorn sat at a U-shaped table in a
high-ceilinged room whose walls were hung with heavy and very ancient
tapestries. The dozen members of the council were all old men,
gray-beards who seemed dwar