Because science will never know everything, you are allowed reasonable guesses where calculation breaks down. Nonetheless — quite apart from flaws which sharp-eyed readers may discover in your facts or logic — you can be pretty sure that eventually science will make discoveries which cast doubt, to say the very least, on various of your assumptions. History will have moved on, too, in directions you had not foreseen for your imaginary future. You are invited to play what Clement calls “the game” with this unrevised text of mine.

I was saved from making one grievous error, by my wife. Looking over my proposed life cycle of the Diomedeans, she exclaimed, “Hey, wait, you have the females flying thousands of miles each year while they’re the equivalent of seven months pregnant. It can’t be done. I know.” I deferred to the voice of experience and redesigned. As I have remarked elsewhere, planet-building ought to be good therapy for the kind of mental patient who believes he’s God.

Despite the hazards, I’ve come back to it again and again, always hoping that readers will share some of the pleasure therein.

—Poul Anderson

I

Grand Admiral Syranaxhyr Urnan, hereditary Commander-in-Chief of the Fleet of Drak’ho, Fisher of the Western Seas, Leader in Sacrifice, and Oracle of the Lodestar, spread his wings and brought them together again in an astonished thunderclap. For a moment, it snowed papers from his desk.

“No!” he said. “Impossible! There’s some mistake.”

“As my Admiral wills it,” Chief Executive Officer Delp hyr Orikan bowed sarcastically. “The scouts saw nothing.”