He forced himself to forget about it; he had a date with Dee again that night, and he was not going to let something silly like this bother him. But bother him it did. Unlike the night before, the date was an utter fiasco, a complete flop. Dee sensed his mood, misinterpreted it, complained of a headache, and went home early. Turnbull slept badly that night. Next morning, he had an appointment with one of the executives of U.C.L.I.--University of Columbia in Long Island--and, on the way back he stopped at the spaceport to see what he could find out. But all he got was purely negative information. On his way back to Manhattan, he sat in the autocab and fumed. When he reached home, he stalked around the apartment for an hour, smoking half a dozen cigarettes, chain fashion, and polishing off three glasses of Bristol Cream without even tasting it. Dave Turnbull, like any really top-flight investigator, had developed intuitive thinking to a fine art. Ever since the Lancaster Method had shown the natural laws applying to intuitive reasoning, no scientist worthy of the name failed to apply it consistently in making his investigations. Only when exact measurement became both possible and necessary was there any need to apply logic to a given problem. A logician adds two and two and gets four; an intuitionist multiplies them and gets the same answer. But a logician, faced with three twos, gets six--an intuitionist gets eight. Intuition will get higher orders of answers from a given set of facts than logic will. Turnbull applied intuition to the facts he knew and came up with an answer. Then he phoned the New York Public Library, had his phone connected with the stacks, and spent an hour checking for data that would either prove or disprove his theory. He found plenty of the former and none of the latter. Then he called his superiors at Columbia. He had to write up his report on the Lobon explorations. Would it be possible for him to take a six-month leave of absence for the purpose? It would. The following Saturday, Dr. Dave F. Turnbull was on the interstellar liner _Oriona_, bound for Sirius. * * * * * If ever there was a Gold Mine In The Sky, it was Centaurus City. To the cultural xenologists who worked on its mysterious riches, it seemed to present an almost inexhaustible supply of new data. The former inhabitants had left everything behind, as though it were no longer of any value whatever. No other trace of them had as yet been found anywhere in the known galaxy, but they had left enough material in Centaurus City to satisfy the curiosity of Mankind for years to come, and enough mystery and complexity to whet that curiosity to an even sharper degree.