The scientist said quietly, "Of the sixteen specimens you sent me, all but one died within ten days after inoculation." "Ah? And the one?" "That is the strange thing. It would seem that--the virus has some preference in victims." The Dictator blinked, his most marked expression of surprise. "Explain!" Euge's face was unreadable. "Before I go into details," he suggested, "let us consider the nature of the perfect biological weapon." "Perhaps you have discovered the perfect weapon?" The Dictator frowned; "you are being obscure." "Then," said Euge stolidly, "suppose I put it negatively. What is wrong with most biological weapons?" "They are treacherous." "Exactly. Virus RM3 was our best development up to now; it has a contagion index and mortality rate of 100, with the psychological advantage of bringing about death in a rather repulsive fashion; it is easily produced and distributed, and there is no known counteragent. So it cannot be used as a weapon; it is too dangerous to the user." "We were over that before," said the Dictator. They had been, and he had found it hard to stomach. Especially when he reflected that the enemy, while it was improbable they had duplicated the creation of RM3, might have equally deadly weapons, which similar considerations would deter them from using--unless driven to suicidal retaliation. It was known, though, that the enemy had been fortunately slow in developing the technique of disease mutation--the methods of irradiation, centrifugal selection and automatic scanning which could produce and analyze thousands of cultures at a time, compress millions of years of micro-organic evolution into weeks or days. "The single case of immunity to RM4," said Euge drily, "had no bases that became evident either at once or on the closest comparison of the physiological data, both pre-inoculation and post mortem. I was on the point of giving up and deciding to repeat the experiment, when it occurred to me to contact the Political Police and ask for their dossiers on all the specimens. After a little delay, my request was granted--" "I know," said the Dictator impatiently; "I approved it myself." "Well--the fifteen men who died of RM4 were run-of-the mill criminals and political offenders--malcontents stupid enough to express themselves antisocially. But the survivor was a Witness of the Lord--a religious maniac, arrested for overstepping the limits of toleration in an impromptu sermon. A man of scanty intelligence, barely above the euthanasia level. "Those facts, however, were less interesting than the letter attached to the dossier. It stated that, after a review of the case inspired by my particular interest in it, the Political Police had concluded that the man's arrest had been a mistake. You know that those fanatics, though not our most desirable elements, are mostly harmless and even useful, with their 'whatever is, is right' theology. This one's loyalty seems to have been beyond question."