"That's right," Westover sat down dizzily. "I've been aboard your ark for some time now, though. Only as an ectoparasite." "It's high time you joined the endoparasites. Lucky you scratched around enough up there to create repercussions we could feel down here. You got the same idea, then?" "I stumbled onto it," Westover admitted. "I was wandering across country--my plane crashed on the way back from that South American bug hunt dreamed up by somebody who'd been reading Wells' _War of the Worlds_. I think my pilot went nuts; you could see too much of the destruction from up there.... But I got out in one piece and started walking--looking for some place with people and facilities that could try out my method of killing the monsters. I thought--I still think--I had a sure-fire way to do that--but I didn't realize then that it was too late to think of killing them off." Sutton nodded thoughtfully. "It was too late--or too early, perhaps. We'll have to talk that over." Westover finished the brief account of his coming to dwell on the monster's back. The other grinned happily. "You began with the practice, where I worked out the theory first." "I haven't got so far with the theory," said Westover, "but I think I've got the main outlines. Until the monsters came, man was a parasite on the face of the Earth. Fundamentally, parasitism--on the green plants and their by-products--was our way of life, as of all animals from the beginning. But the monsters absorbed into themselves all the plant food and even the organic material in the soil. So we have only one way out--to transfer our parasitism to the only remaining food source--the monsters themselves. "The monsters almost defeated us, because of their two special adaptations of extreme size and ability to cross space. But man has always won the battle of adaptations before, because he could improvise new ones as the need arose. The greatest crisis humanity ever faced called for the most radical innovation in our way of life." "Very well put," approved Sutton. "Except that you make it sound easy. By the time I'd worked it out like that, things were already in such a turmoil that putting it into effect was the devil's own job. About the only ones I could find to help me were the Preacher and his people. They have the faith that moves mountains, that has made this self-moving mountain inhabitable." "It is inhabitable?" Westover's question reflected no doubt. * * * * *