“By studying the modern speech and ancient manuscripts of the descendants of that P’an-ku who, thousands of years ago, journeyed from your world to mine,” replied the professor. “Bring a cushion for the Khan from Du Gong, and cut his bonds,” ordered Kwan Tsu Khan. “Then retire outside the door, that we may hold private converse.” Lin Ching drew his sharp knife and severed the bonds which held the professor’s numbed wrists behind his back. Then he brought a great, thick cushion which he placed on the floor behind his captive, and assisted him to sit down. After a deep obeisance toward the dais, he retired to the passageway, closing the diamond-shaped door after him. “Now, Am-Er-I-Khan,” said Kwan Tsu Khan, “just how much do you know about the history of that great and worshipful P’an-ku who journeyed to your world so long ago? And what can you tell me of his descendants?” “I have only conjectured that such a person existed and traveled to our world,” replied the professor, chafing his numbed wrists. “Even his descendants, who are today numerous as the celestial stars, refer to him only as the first man, their first ancestor. It was by combining the statements in your message to us with the traditions of the descendants of P’an-ku and noting the easily recognized racial resemblance as well as the philological similarity, that I formed my theory.” “Your conjecture,” said Kwan Tsu Khan, “must be correct, for our most ancient records tell of the journey of one of the mightiest of our P’an-kus to Du Gong, after our terrific battle with Lu Gong had vitiated our surface atmosphere to such an extent that life on Ma Gong was impossible except in the deepest caves. But nothing was ever heard from P’an-ku thereafter, and it was thought that he lost his life in the attempt to reach Du Gong.” “That is interesting,” answered the professor. “I understand that you refer to your world as Ma Gong, and to mine as Du Gong, but may I ask what Lu Gong is?” “Why, Lu Gong is the world which circles the great Lord Sun in an orbit just outside that of Du Gong—the world which appears red to your watchers of the sky.” “Then Lu Gong is the world we call Mars,” said the professor. “And you have a tradition of a war with Mars?” “We have more than a tradition. Our world carries the scars of that war, and will carry them to eternity.” “I should be interested in hearing about it.” “Very well, but I can only review it briefly, as time presses. Many thousands of years ago our world was a planet with its own orbit, which was midway between that of your world and Lu Gong, or Mars, as you call it. It rotated on its axis, even as do your planet and Lu Gong, and its days and nights were shorter and its years longer than your own are today.