Kethra, and all his men, had pressed us to return with them to Kom, but we refused. An intolerable nostalgia, a longing for our own time, filled us, and our four friends were as eager to return to their own centuries as we were. And so, standing with them beside our time-car, we bade our friends of Kom farewell. "You do wisely, men of the past," said Kethra. "It is not good that a man should leave his own time and venture into others. The secret of time-traveling is an evil secret. And when our fleet has returned to Kom, every car in it will be stripped of the time-wave apparatus, and all those time-wave mechanisms will be destroyed by us. For now that our end has been accomplished, and the Raider destroyed, none of us will ever again venture into past or future." "You speak truth," said Lantin, sadly; "for though we came on through the ages ourselves, we could not save our friend. And when we have returned our four friends here to their own ages, and reached ours again, we too will destroy this car. And the secret of time-traveling will remain with us, a secret." We each grasped Kethra's hand, waved farewell to the hundreds in the air-boats on the ground around us, and then entered our own car. With our four friends, its interior was crowded, but there was enough room for Lantin to manipulate the controls, and so the car rose swiftly, circled for a moment above the air-boats on the ground, then fled swiftly toward the southwest. Behind us the green, warm land of the Kanlars faded to a speck against the ice, and as we sped on, we moved through time also, passing swiftly into the past. * * * * * Three hours later we hung above a vast highland country, having penetrated into the past to the year 1520, four hundred years before our own time. And below us hung the white city of Tenochtitlan, metropolis of the Aztec people. We slanted down toward it, through the darkness, for we had come to it at night. Toward the city's edge was the glimmer of a broad lake, and from great pyramids flashed burning fires of crimson. In its dark streets was a stir of movement, and up to us came the roar of a fierce battle, with cries of wounded, and twang of bows, and here and there the roar of an arquebus or cannon. Ixtil leaned toward the window, gazed down with tense interest. "It is my people," he said, turning to us, "my city, my time." And so, swooping down upon the city through the concealing darkness, we halted the car on a flat, white roof, and Ixtil stepped out. He turned, and with more emotion than I had ever yet seen upon his fierce face, bade us farewell. D'Alord, Denham, Fabrius, each wrung his hand silently, and then the Aztec turned to me. He drew the saw-edged sword from his belt, and handed it to me, hilt-foremost. "Take it," he told me. "I can give you nothing else, and it may remind you of our fight on the stair, comrade, when you have reached your own time."