They sat in Professor Staunton's laboratory, a square chamber where Earthly equipment taken from the wreck of his space-ship was mingled with typically Lunarian furniture and equipment. The walls were light blue, of that polished composition resembling bakelite that was used for building in the Caverns. The walls were about ten feet high, and they ended in an ornamental cornice without any ceiling or roof at all. Overhead there was a glow of misty light, and far above the rocky top of the cavern. "Why should we need roofs?" Diana said in reply to Larry's surprised comment. "Here in these Caverns there is neither rain nor snow nor wind, nor any change in temperature at all. The walls give privacy, and there is no need for anything else." Ripon was bending over a table on which Staunton had spread a large map of the Moon. The cavern of Chotan was indicated by a red dot, and Larry saw that there were a dozen others scattered around within a radius of a few hundred miles. "Our space-cruiser was wrecked near one of the entrances to this cavern when we landed here thirty years ago," Staunton said. "As you have guessed, it was the inability to land safely with rockets, in a practically airless atmosphere where helicopters were useless, that smashed us. As you did, we had fortunately put on space suits before trying to land. Our ship was too badly wrecked for any chance of return." "But how have you succeeded in getting all these people to learn English?" Ripon asked. "They knew that language before I came! But it is best that I give you a hasty outline of Lunarian history. The simple-minded but husky Insect-men were the aboriginal inhabitants of the Moon. Long æons ago, while most of the people of Earth were living crudely in caves and using chipped stones for tools and weapons, an isolated people developed a high civilization in what I have roughly identified as the region of the Himalayas. A series of great earthquakes destroyed their civilization, but a large number of them escaped and came to the Moon in some kind of a space-ship. Here they found, in those days, a small planetary body that had a thin but breathable air. They founded a civilization on the other side of the Moon where it is always sunny, and called it Gral-Thala. Those were pleasant days, if the old legends are to be believed, the Golden Age of Lunarian civilization." For a moment Staunton paused. All those in the room, including the Lunarians who had been familiar with this tale since childhood, hung intently on his words. The broad face of Pyatt of Kagan was somber and moody as he sat bent forward with the scabbard of his sword resting across his armored knees.