terms were contradictory.

"Not as much as you think," Ixtl continued imperturbably. "As you will
find out, I was speaking quite precisely." He paused and eyed Matson
thoughtfully. "It seems as though the only way to remove your
disturbing presence is to show you that our technology is of no help
to you. I will make a bargain with you. We shall show you our
machines, and in return you will stop harassing us. We will do all in
our power to make you understand; but whether you do or do not, you
will promise to leave and allow us to continue our studies in peace.
Is that agreeable?"

Matson swallowed the lump in his throat. Here it was--handed to him on
a silver platter--and suddenly he wasn't sure that he wanted it!

"It is," he said. After all, it was all he could expect.

They met that night at the spaceship. The aliens, tall, calm and cool;
Matson stocky, heavy-set and sweating. The contrast was infernally
sharp, Matson thought. It was as if a primitive savage were meeting a
group of nuclear physicists at Los Alamos. For some unknown reason he
felt ashamed that he had forced these people to his wishes. But the
aliens were pleasant about it. They took the imposition in their usual
friendly way.

"Now," Ixtl said. "Exactly what do you want to see--to know?"

"First of all, what is the principle of your space drive?"

"There are two," the alien said. "The drive that moves this ship in
normal space time is derived from Lurgil's Fourth Order equations
concerning the release of subatomic energy in a restricted space time
continuum. Now don't protest! I know you know nothing of Lurgil, nor
of Fourth Order equations. And while I can show you the mathematics,
I'm afraid they will be of little help. You see, our Fourth Order is
based upon a process which you would call Psychomathematics and that
is something I am sure you have not yet achieved."

Matson shook his head. "I never heard of it," he admitted.

"The second drive operates in warped space time," Ixtl continued,
"hyperspace in your language, and its theory is much more difficult
than that of our normal drive, although its application is quite
simple, merely involving apposition of congruent surfaces of hyper and
normal space at stress points in the ether where high gravitational
fields balance. Navigation in hyperspace is done by electronic
computer--somewhat more advanced models than yours. However, I can't
give you the basis behind the hyperspace drive." Ixtl