"Great was our consternation to find ourselves on an alien world, inhabiting alien bodies; and bitter were we when we realized the egos that had formerly possessed these organic vehicles were now dwelling in _our_ bodies, on our own fair world. A planet of deadness was this upon which our intellects had been cast, but we were determined to live on and someday know vengeance. "In a word: in one horrible second, and much against our will, we had traded worlds with a desperate, dying race--our sphere of abundance for theirs of desolation. "The machine with which the usurpers had accomplished this was beyond our comprehension, though our scientists worked long and feverishly to solve its secret. Long after, we came to the conclusion the machine had been captured from the Beast People and one of their number forced to operate it. "Truly, we found a dying half-man in this cavern. He had been poisoned, so we could not force him to operate the machine for us and take back the planet and organisms that were rightfully ours. Not until many years after did we succeed in capturing a number of the Beast People, only to find they had lost the knowledge of the ego-transposer's working. They were devolving at a rapid pace, and soon we, too, began to know the ravages of degeneration, though it did not act with such speed on us--perhaps only for the reason that we were determined to stave it off and one day return to our much-mourned world. "Here were we, a rising race, now doomed to extinction by a treacherous people too weak to face the destiny ordained for them. It is true these people were intelligent, after a fashion, but there is little knowledge to be had on this rock-world and when the limit is reached, the mind must retrogress. "There will be mutations on our lost world, for our planet was possessed of a much larger population than this of the transgressors. Thus when the hellish ego-transposer effected the change, many on our world were left mindless, with only the instincts of the beast remaining. Inter-breeding will greatly reduce the intelligence of the entire population for a time--though they will without doubt arise once more to a new greatness, for the means are there for them. "There can only be sorrow, despair, and untold misery for us. Before the gods, there can be no greater trespass than this." Kac's voice trailed away. Sick dread was on Gene's face. "Kac," he whispered, "What was the name of this world that was stolen from you?" "Ours was the third world nearest the sun," the tall warrior answered with true regret. "The planet you call Earth...." Gene's torment of mind knew no bounds in the following hours. Kac had left him in the cavern, warning him not to destroy the Talkers or the tribe would surely slay him. The biologist had given his word and even if he had wished, he could not have violated it; for nothing short of an atomic-cannon could rend the metal of which the titanic machines were built.