"_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."