"Limitation of materials," said Dreyer. "The moon obviously is lacking in mineral resources, being composed chiefly of nonmetallic silicates. The glass knife our friend used on the corpse indicates metal starvation; this highway clinches it because it shows they have a highly developed technology of glass-working. Therefore, we are very definitely not in the presence of a primitive civilization as we supposed. We'd better watch our step because our friend seemed disillusioned about our failure to save his injured companion."

They chose a direction along the highway and pursued it a few feet above the surface. They traveled for twenty minutes or so with no break in the forest about them or the shining highway below.

Then abruptly a figure came into view in the distance. It was moving rapidly. Terry squinted and suddenly exclaimed, "We come how many light years to find a super-civilization, and we find bike riders!"

Phyfe said, "I don't see anything strange in it. Certainly the bicycle is an obvious mode of locomotion in a moderately mechanical culture. It may or may not imply a lack of self-propelled mechanisms."

"Recognize that fellow?" asked Underwood.

They drifted forward as the rider approached rapidly. Finally they could see his features plainly and recognized him as the rebellious one of their morning encounter.

"I wonder if he is on his way back to see us again," said Terry.

"Our meeting is fortunate," said Dreyer. "I want to know what he did with that organ he removed from the corpse. I've never come across anything quite like that in all my ethnological studies. I suspect it may be some rite associated with the belief in that organ as the seat of life, just as the heart was once regarded among us."

They slowed as they came to the man—for so they had come to think of him in their own minds. He halted also and regarded them balefully. Then furious speech came to his lips. "Shazer na jourli!"

Dreyer frowned and muttered a few syllables slowly. The stranger repeated the furious assertion.