The mutation was a psychic twist, probably originating in some obscure gene related to the endocrine system. It was extraordinarily hard to describe-every categorical statement about it had the usual quota of exceptions and qualifications. But one might, to a first approximation, call it extreme xenophobia. It is normal for Homo sapiens to be somewhat wary of outsiders till he has established their bona fides; it was normal for Homo Kolreshi to hate all outsiders, from first glimpse to final destruction.

Naturally, such an instinct produced a tendency to inbreeding, which lowered fertility, but systematic execution of the unfit had so far kept the stock vigorous. The instinct also led to strongarm rule within the nation; to nomadism, where a planet was only a base like the oasis of the ancient Bedouin, essential to life but rarely seen; to a cult of secrecy and cruelty, a religion of abominations; to an ultimate goal of conquering the accessible universe and wiping out all other races.

Of course, it was not so simple, nor so blatant. Among themselves, the Kolreshites doubtless found a degree of tenderness and fidelity. Visiting on neutral planets-i.e., planets which it was not yet expedient to attack-they were very courteous and had an account of defending themselves against one unprovoked aggression after another, which some found plausible. Even their enemies stood in awe of their personal heroism.

Nevertheless, few in the galaxy would have wept if the Kolreshites all died one rainy night.

Hans von Thoma Rusch brought his speedster to the great whaleback of the battleship. It lay a light-year from his sun, hidden by cold emptiness; the co-ordinates had been given him secretly, together with an invitation which was more like a summons.

He glided into the landing cradle, under the turrets of guns that could pound a moon apart, and let the mechanism suck him down below decks. When he stepped out into the high, coldly lit debarkation chamber, an honor guard in red presented arms and pipes twittered for him.