Before going into the cave he paused to take another survey. From his spot in the clearing, which was almost on the top of the hill, he could look over the tree tops and see most of the island, except where other hills barred his view. The island had stopped moving and had settled down against the plain itself. Now, to the untutored eye, the entire mass looked like a clump of dirt, rocks and vegetation for some reason rising from the grassy seas. It would remain so until dusk, when it would again launch itself upon its five-mile-an-hour journey to the east. And once having reached a certain point there, it would reverse itself and begin its nocturnal pilgrimage toward the west. Back and forth, shuttling for how many thousands of years? What was its purpose, and whom had its builders been? Surely they could not have conceived in their wildest dreams of its present use, a mobile fortress for a tribe of cannibals? Nor could they have seen to what uses their dust-collectors would be put. They couldn't have guessed that, millennia thence, men ignorant of their originally intended purpose would be using the devices as part of their religious ritual and of human sacrifice. Green left the others in the room next to the one where the explosion had taken place. They lay down on the hard floor and at once went to sleep. He, however, felt that there were certain things that had to be done and that he was the only one physically capable of doing them. 20 Though he hated to go back into the altar room, he forced himself. The scene of carnage was bad enough, but not as repulsive as he'd expected. Dust had thrown a gray veil of mercy over the bodies. They looked like peaceful gray statues; most of them had not burned on the outside but had died because they'd breathed the first lung-scorching wave of air directly. Nevertheless, despite the look of peace and antiquity, the odor of burned flesh from Aga hung heavy. Lady Luck bristled and arched her back, and for a moment Green thought she was going to leap from his shoulder and run away. He said, "Take it easy," then decided that she must have smelled this often before. Her present reaction was based on past episodes; probably, there had been great excitement then. The cats, being taboo animals, must have been figures of some importance in the sacrificial ceremonies. Cautiously, the man approached the wall of dirt behind the altar, even though he did not think there would be any danger for some time to come. The altar itself was comparatively undamaged. Surprised at this, he ran his hand over it and found out that it was composed of baked clay, hard as rock. The chair and metal rod had not been torn loose. Both were tightly bolted down with huge studs which he supposed had been taken off wrecked 'rollers.