But people still grew old. The process wasn't as hideous as it had been. You needn't shuffle in arthritic feebleness. Your mind was clear, your skin wrinkled slowly. Centenarians were not uncommon these days. But very few reached 150. Nobody reached 200. Imperceptibly, the fires burned low ... vitality was diminished, strength faded, hair whitened, eyes dimmed. The body responded less and less well to regenerative treatment. Finally it did not respond at all. You got so weak that some small thing you and your doctor could have laughed at in your youth, took you away. You still grew old. And because you grew old, you still died. The unicellular organism did not age. But "age" was a meaningless word in that particular case. A man could be immortal via his germ cells. The micro-organism could too, but it gave the only cell it had. Personal immortality was denied to both man and microbe. Could sheer mechanical wear and tear be the reason for the decline known as old age? Probably not. The natural regenerative powers of life were better than that. And observations made in free fall, where strain was minimized, indicated that while null-gravity had an alleviating effect, it was no key to living forever. Something in the chemistry and physics of the cells themselves, then. They did tend to accumulate heavy water--that had been known for a long time. Hard to see how that could kill you ... the percentage increase in a lifetime was so small. It might be a partial answer. You might grow old more slowly if you drank only water made of pure isotopes. But you wouldn't be immortal. Radek shrugged. He was getting near the end of his trip. Let the Institute people answer his questions. * * * * * The Four Corners country is so named because four of the old American states met there, back when they were still significant political units. For a while, in the 20th century, it was overrun with uranium hunters, who made small impression on its tilted emptiness. It was still a favorite vacation area, and the resorts were lost in that great huddle of mountains and desert. You could have a lot of privacy here. Gliding down over the moon-ghostly Pueblo ruins of Mesa Verde, Radek peered through the windscreen. There, ahead. Lights glowed around the walls, spread across half a mesa. Inside them was a parkscape of trees, lawns, gardens, arbors, cottage units ... the Institute housed its people well. There were four large buildings at the center, and Radek noted gratefully that several windows were still shining in them. Not that he had any compunctions about getting the great Dr. Lang out of bed, but-- He ignored the public landing field outside the walls and set his boat down in the paved courtyard.