“The units worked, and the plan was to move Ma Gong behind your world, where it would be shielded from the bombardment of meteoric clusters. This was accomplished, but when the proper place had been reached, the scientists came in contact with terrific magnetic forces on which they had not counted—their power units were incapacitated, and they found themselves not only bound to the Great Lord Sun, but to your world as well. Ma Gong’s axial rotation was affected, so it eventually became as you now observe it. Its orbit, after it settled down, was much as it is today, so that it was now behind your world, now racing ahead on an outer curve, now lagging behind on an inner one, only to be caught up at a certain point and jerked forward once more to repeat the whole process. “The bombardment from Lu Gong continued until both worlds were nearly without people to carry on the battle. P’an-ku, himself, was slain when the imperial city was destroyed by a meteoric cluster. The atmosphere of Ma Gong became so thin that the few people who remained alive did so because they retreated into the great inner caverns where what remained of the atmosphere had flown like water flows—toward the source of gravitational pull. “The operators of the great ray projectors finally died at their posts for want of air. The bombardment from Lu Gong gradually waned as its inhabitants succumbed to the power of our ray projectors, until it ceased altogether. “Only a few hundreds of our people were left alive in the great caverns, and there was not among them one scientist—for the scientists had all died in defense of our world. So far as scientific knowledge went, the race was thus set back for thousands of years. The simple people who had fled to the caves—for the most part agriculturalists and tradesmen—knew not how to construct an interplanetary vehicle, a green ray projector, an atmosphere disintegrator, or any of the thousands of useful but intricate devices formerly made by† the scientists. They were forced to begin with simpler things and gradually build a new civilization and a new school of scientists. “Even the libraries, which would have been of inestimable value to them, were on the airless surface of Ma Gong where they could not be reached, and most of these had been destroyed by the meteoric clusters projected from Lu Gong. The others succumbed to age and the incessant battering of planetesimal particles which followed the destruction of our atmosphere, before they could be reached.