ds of human thought and
endeavor had been opened.

No trace of the alien spaceships had been uncovered, but the
anti-gravitational devices in their aircraft, plus the basic principles
of Man's own near-light-velocity drive had given Man the ultralight
drive.

Their knowledge of social organization and function far exceeded that of
Man, and the hints taken from the deciphered writings of the aliens had
radically changed Man's notions of government. Now humanity could build
a Galactic Civilization--a unity that was neither a pure democracy nor
an absolute dictatorship, but resulted in optimum governmental control
combined with optimum individual freedom. It was _e pluribus unum_ plus.
Their technological writings were few, insofar as physics and chemistry
were concerned. What there were turned out to be elementary texts rather
than advanced studies--which was fortunate, because it had been through
these that the cultural xenologists had been able to decipher the
language of the aliens, a language that was no more alien to the modern
mind than, say, ancient Egyptian or Cretan.

But without any advanced texts, deciphering the workings of the
thousands of devices that the aliens had left behind was a tedious job.
The elementary textbooks seemed to deal with the same sort of science
that human beings were used to, but, at some point beyond, the aliens
had taken a slightly different course, and, at first, only the very
simplest of their mechanisms could be analyzed. But the investigators
learned from the simpler mechanisms, and found themselves able to take
the next step forward to more complex ones. However, it still remained a
fact that the majority of the devices were as incomprehensible to the
investigators as would the function of a transistor have been to James
Clerk Maxwell.

In the areas of the social sciences, data was deciphered at a fairly
rapid rate; the aliens seemed to have concentrated all their efforts on
that. Psionics, on the other hand, seemed never to have occurred to
them, much less to have been investigated. And yet, there were devices
in Centaurus City that bore queer generic resemblances to common
Terrestrial psionic machines. But there was no hint of such things in
the alien literature.

And the physical sciences were deciphered only slowly, by a process of
cut-and-try and cut-and-try again.

The investigations would take time. There were only a relatively small
handful of men working on the pr