As our own cruiser drove down toward the mass of traffic, though, it cleared away from before us instantly; for the symbol of the Federation on our bows was known from Canopus to Fomalhaut, and the cruisers of its fleet were respected by all the traffic of the Galaxy. Arrowing down through this suddenly opened lane we sped smoothly down toward the planet's surface, hovering for a moment above its perplexing maze of white buildings and green gardens, and then slanting down toward the mighty flat-roofed building which housed the Bureau of Astronomical Knowledge. As we sped down toward its roof I could not but contrast the warm, sunny green panorama beneath with the icy desert which the planet had been until two hundred thousand years before, when the scientists of the solar system had devised the great heat-transmitters which catch the sun's heat near its blazing surface and fling it out as high-frequency vibrations to the receiving-apparatus on Neptune, to be transformed back into the heat which warms this world. In a moment, though, we were landing gently upon the broad roof, upon which rested scores of other shining cruisers whose crews stood outside them watching our arrival. Five minutes later I was whirling downward through the building's interior in one of the automatic little cone-elevators, out of which I stepped into a long white corridor. An attendant was awaiting me there, and I followed him down the corridor's length to a high black door at its end, which he threw open for me, closing it behind me as I stepped inside. * * * * * It was an ivory-walled, high-ceilinged room in which I found myself, its whole farther side open to the sunlight and breezes of the green gardens beyond. At a desk across the room was sitting a short-set man with gray-streaked hair and keen, inquiring eyes, and as I entered he sprang up and came toward me. "Ran Rarak!" he exclaimed. "You've come! For two days, now, we've been expecting you." "We were delayed off Aldebaran, sir, by generator trouble," I replied, bowing, for I had recognized the speaker as Hurus Hol, chief of the Bureau of Astronomical Knowledge. Now, at a motion from him, I took a chair beside the desk while he resumed his own seat. A moment he regarded me in silence, and then slowly spoke. "Ran Rarak," he said, "you must have wondered why your ship was ordered back here to the solar system. Well, it was ordered back for a reason which we dared not state in an open message, a reason which, if made public, would plunge the solar system instantly into a chaos of unutterable panic!"