people.

They learned of the origin of the races that inhabited Europa and
Ganymede. Ages before, it was necessary for the peoples of the then
thickly populated Jupiter to cast about for new homes due to the
cooling of the surface of that planet. Life was becoming unbearable.
In those days there were two dominant races on the mother body, a
gentle and peaceful people of great scientific accomplishment and a
race of savage brutes who, while very clever with their hands, were of
lesser mental strength and of a quarrelsome and fighting disposition.

Toward the last the population of both main countries was reduced to
but a few survivors, and the intelligent race had discovered a means
of traversing space and was prepared to leave the planet for the more
livable satellite--Europa. Learning of these plans, the others made a
treaty of perpetual peace as a price for their passage to another
satellite--Ganymede. The migration began and the two satellites were
settled by the separate bands of pioneers and their new lives begun.

* * * * *

The perpetual treaty had not been broken since, but the energies of
the warlike descendants of those first settlers of Ganymede were
expended in casting about for new fields to conquer. Through the ages
they cast increasingly covetous eyes on those inner planets, Mars,
Terra and Venus. Not having the advantage of the Rulden, they knew of
these bodies only what could be seen through their own crude optical
instruments and what they had learned by word of mouth from certain
renegade Europans they were able to bribe.

While their neighbors of the smaller satellite were engaged in
peaceful pursuits, tilling the soil and making excellent homes for
themselves, the dwellers on Ganymede were fashioning instruments of
warfare and building a fleet of space-ships to carry them to their
intended victims. It was a religion with them; they could think of
nothing else. An unscrupulous scientist of Europa sold himself to them
several generations previously and it was this scientist who had made
the plans for their space-fliers and had contrived the deadly weapons
with which they were armed. He likewise taught them the language of
Cos and it now was spoken universally throughout Ganymede in
anticipation of the glorious days of conquest.

"You honestly believe them able to do this?" asked Carr, still
skeptical after two days of discussion.

"I know it as a certainty," Det