It was a slow, tedious business, but the crystal monolith was patient. Neither it, nor its replicas scattered across half the globe, expected to succeed with all the scores of groups involved in the experiment. A hundred failures would not matter, when a single success could change the destiny of the world.

By the time of the next new moon, the tribe had seen one birth and two deaths. One of these had been due to starvation; the other had occurred during the nightly ritual, when a man-ape had suddenly collapsed while attempting to tap two pieces of stone delicately together. At once, the crystal had darkened, and the tribe had been released from the spell. But the fallen man-ape had not moved; and by the morning, of course, the body was gone.

There had been no performance the next night; the crystal was still analyzing its mistake. The tribe streamed past it through the gathering dusk, ignoring its presence completely. The night after, it was ready for them again. The four plump man-apes were still there, and now they were doing extraordinary things. Moon-Watcher began to tremble uncontrollably; he felt as if his brain would burst, and wanted to turn away his eyes. But that remorseless mental control would not relax its grip; he was compelled to follow the lesson to the end, though all his instincts revolted against it.

Those instincts had served his ancestors well, in the days of warm rains and lush fertility, when food was to be had everywhere for the plucking. Now times had changed, and the inherited wisdom of the past had become folly. The man-apes must adapt, or they must die – like the greater beasts who had gone before them, and whose bones now lay sealed within the limestone hills.