ly transparent mica, each
sheet a foot in diameter, and a dozen large water-clear quartz crystals.

"Float, from higher up on the mountain," he said. "The mica and crystals
are in place up there if we could only reach them. Other minerals,
too--I panned traces in the canyon bottoms. But no iron."

Lake examined the sheets of mica. "We could make windows for the outer
caves of these," he said. "Have them double thickness with a wide air
space between, for insulation. As for the quartz crystals...."

"Optical instruments," Craig said. "Binoculars, microscopes--it would
take us a long time to learn how to make glass as clear and flawless as
those crystals. But we have no way of cutting and grinding them."

Craig went to the east that fall and to the west the next spring. He
returned from the trip to the west with a twisted knee that would never
let him go prospecting again.

"It will take years to find the metals we need," he said. "The
indications are that we never will but I wanted to keep on trying. Now,
my damned knee has me chained to these caves...."

He reconciled himself to his lameness and confinement as best he could
and finished his textbook: GEOLOGY AND MINERAL IDENTIFICATION.

He also taught a geology class during the winters. It was in the winter
of the year four on Ragnarok that a nine-year-old boy entered his class;
the silent, scar-faced Billy Humbolt.

He was by far the youngest of Craig's students, and the most attentive.
Lake was present one day when Craig asked, curiously:

"It's not often a boy your age is so interested in mineralogy and
geology, Billy. Is there something more than just interest?"

"I have to learn all about minerals," Billy said with matter-of-fact
seriousness, "so that when I'm grown I can find the metals for us to
make a ship."

"And then?" Craig asked.

"And then we'd go to Athena, to kill the Gerns who caused my mother to
die, and my grandfather, and Julia, and all the others. And to free my
father and the other slaves if they're still alive."

"I see," Craig said.

He did not smile. His face was shadowed and old as he looked at the boy
and beyond him; seeing again, perhaps, the frail blonde girl and the two
children that the first quick, violent months had taken from him.

"I hope you succeed," he said. "I wish I was young so I could dream of
the same thing. But I'm not ... so let's get back to the identification
of the ores that will be needed to make a ship to