Nothing, Kayin thought, but the danger of depopulating most of a planet. His mind went back to what had happened on the second planet of his own sun, what had almost happened on the fourth planet. Within the space of a few hundred centads of time, the second planet, with its population of four billion, had lost every inhabitant, and become a sterile monument of a dead civilization. Only the warning of what had already taken place had enabled the second planet to survive. And in this place too, disaster would strike quickly. Kayin had begun to read more and more, and he knew what was taking place here. Science had developed quickly, but sporadically. Vast regions had remained untouched by it, masses of people knew nothing of it but the name and the fact that it could perform miracles. True, they had learned that certain discoveries might lead to disaster as well as to the improvement of their lives, but they still failed to test their discoveries fully before using them, they still failed to exercise the necessary controls. The young man, Blayson, had made his discovery ahead of its proper time. At the rate at which human science was progressing, thought Kayin, at least a hundred years would have to pass before such a discovery could be considered safe. At the present stage, it simply could not be controlled. The concentrated cosmic rays would, as Blayson evidently anticipated, cause tremendous mutations in living organisms, in the molds and mycetes of different kinds, it would lead to the manufacture of useful antibiotics. But they would also lead to the production of entirely new forms of sub-microscopic life, forms not susceptible to ordinary methods of sterilization, forms that would multiply with inexorable speed. These forms produced from bits of human tissue would inevitably be deadly to human beings and related species. He himself, thought Kayin, possessed of a different body chemistry, might escape. But he would be the only intelligent creature to do so. And after the viruses had done their work, the planet, in its desolation and sterility, would resemble the second planet of his own star. If he had learned of the imminence of disaster at the time he first arrived, he would hardly have been affected. He would have hated to see a race disappear. He had the scientist’s desire to keep any race, even the least useful, alive so that he might study it, and at the very worst, write an article about it. But now--and this he realized almost to his amazement--he felt practically human himself. It must be the way he was living and working, the way the others treated him on the job. He did not want to see them annihilated. * * * * *