Only in event of a transit will they ever discover it, though, for Prxl does not reflect light. It hasn't, anyway, for several million years since its inhabitants coated it with a black, light-absorbing pigment derived from its interior. Monumental task, painting a world, for creatures half an inch tall. But worth it, at the time. When they'd shifted its orbit, they were safe from their enemies. There were giants in those days--eight-inch tall marauding pirates from Diemos. Got to Earth a couple of times too, before they faded out of the picture. Pleasant little giants who killed because they enjoyed it. Records in now-buried cities on Diemos might explain what happened to the dinosaurs. And why the promising Cro-Magnons disappeared at the height of their promise only a cosmic few minutes after the dinosaurs went west. But Prxl survived. Tiny world no longer reflecting the sun's rays, lost to the cosmic killers when its orbit was shifted. Prxl. Still civilized, with a civilization millions of years old. Its coat of blackness preserved and renewed regularly, more through tradition than fear of enemies in these later degenerate days. Mighty but stagnant civilization, standing still on a world that whizzes like a bullet. And Mitkey Mouse. * * * * * Klarloth, head scientist of a race of scientists, tapped his assistant Bemj on what would have been Bemj's shoulder if he had had one. "Look," he said, "what approaches Prxl. Obviously artificial propulsion." Bemj looked into the wall-plate and then directed a thought-wave at the mechanism that jumped the magnification of a thousand-fold through an alteration of the electronic field. The image leaped, blurred, then steadied. "Fabricated," said Bemj. "Extremely crude, I must say. Primitive explosive-powered rocket. Wait, I'll check where it came from." He took the readings from the dials about the viewplate, and hurled them as thoughts against the psychocoil of the computer, then waited while that most complicated of machines digested all the factors and prepared the answer. Then, eagerly, he slid his mind into rapport with its projector. Klarloth likewise listened in to the silent broadcast. Exact point on Earth and exact time of departure. Untranslatable expression of curve of trajectory, and point on that curve where deflected by gravitational pull of Prxl. The destination--or rather the original intended destination--of the rocket was obvious, Earth's moon. Time and place of arrival on Prxl if present course of rocket was unchanged. "Earth," said Klarloth meditatively. "They were a long way from rocket travel the last time we checked them. Some sort of a crusade, or battle of beliefs, going on, wasn't there?" Bemj nodded. "Catapults. Bows and arrows. They've taken a long stride since, even if this is only an early experimental thing of a rocket. Shall we destroy it before it gets here?"