understand the principle when—or if—we learn how the wasp holds its spider helpless. Until then, we can only guess. As for identifying the motive that prompted the Hymenops to set up such a balance, I doubt that we ever will. Could a termite understand why men build theaters?"

"There's a possible parallel in that," Stryker suggested. "Maybe this was the Hymenop idea of entertainment. They might have built the bridge as balconies, where they could see the show."

"It could have been a business venture," Farrell suggested. "Maybe they raised the moth larvae or pupae for the same reason we raise poultry. A sort of insectile chicken ranch."

"Or a kennel," Gibson said dryly. "Maybe they bred moths for pets, as we breed dogs."

Farrell grimaced sickly, revolted by the thought. "A pet farm? God, what a diet to feed them!"

Xavier came up from the galley, carrying a tray with three steaming coffee-bulbs. Farrell, still pondering the problem of balance between dominant and dominated species, found himself wondering for the thousandth time what went on in the alert positronic brain behind the mechanical's featureless face.

"What do you think, Xav?" he demanded. "What sort of motive would you say prompted the Hymenops to set up such a balance?"

"Evaluation of alien motivations, conversely," the mechanical said, finishing the Reclamations Handbook quotation which Stryker had begun much earlier, "is essentially impossible because there can be no common ground of comprehension."

It centered the tray neatly on the charting table and stood back in polite but unmenial deference while they sucked at their coffee-bulbs.

"A greater mystery to me," Xavier went on, "is the congenital restlessness that drives men from their own comfortable worlds to such dangers as you have met with here. How can I understand the motivations of an alien people? I do not even understand those of the race that built me."

The three men looked at each other blankly, disconcerted by the ancient problem so unexpectedly posed.

It was Stryker who sheepishly answered it.

"That's nothing for you to worry about, Xav," he said wryly. "Neither do we."

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