The screen changed before his eyes. The work of excavation and reconstruction vanished. Off to one side, olive groves appeared. Then a building with unmistakably Byzantine architecture flashed on. Again Burke twisted the dial. Again. Now whole towns came and went. One moment, the screen showed neat huts and cultivated fields; the next, ruins or no buildings at all. But never a trace of people. People moved too quickly for even the finest settings of the time-spindles to show them. Farther back ... farther ... farther.... And now there was only a great, dark ring on the hillside to mark the palace. Wall-blocks and pillars lay strewn like scorched blocks in all directions. It was as if lightning had blasted the very earth. The few huts to be seen stood far off, as if the site of Knossos were a place accursed, to be avoided under pain of death. A chill touched Burke; and though he'd seen this sight a dozen times before, his fingers trembled. Back farther ... farther.... As swiftly as it had darkened, the screen came bright. The palace rose again, white gypsum walls and columns aglisten in the sunlight. Skillfully, Burke adjusted the detail dial, working forward again to the moment when the palace had crumbled. * * * * * The disaster came at night; that was plain to see. And so fast that the screen could not record the instant when it happened. One second, the buildings were there, solid as only rock could make them. The next, there were only dark, blighted ruins. Of course, the destruction could conceivably have taken hours, yet still show as instantaneous on the scanner. But if a man were to go back to a time, say, twelve hours before the cataclysm.... He'd need to choose the right place, too ... somewhere out of the line of palace traffic--that apartment off the Queen's Megaron, for instance. Not too steadily, Burke set the dials; then straightened. The realization of his own folly flooded through him in the same instant. How could anyone be so mad as to sacrifice his life on the altar of sheer intellectual curiosity? What did it matter if he never knew why Knossos fell? To go through with this because he'd been intrigued by an octopus-decorated Minoan bowl as a child of seven--it was absurd. His place was here--in his own time, his own land. To think otherwise could only be evidence of gross imbalance. He started to reach for the main switch; to turn off the inverter. Simultaneously, a hand rattled the knob of the laboratory's outer door. Burke froze. Now a key clicked in the lock. A voice--the voice of the campus policeman--called, "All right, you! Come on out! We know you're there!" And then, not quite so plainly, the voice of The Professor: "Be careful, officer. He's been acting queerly--thinks I've some kind of strange machine in there. What he needs is a psychiatrist. But till we can get him to one, he may be dangerous."