"Spare me the history lesson," said Thurmon, dryly. "We rebuilt, yes. We survived. In a sense, perhaps, we even made certain advances. There is no longer any economic rivalry, no social distinctions, no external pressure. I think I can safely assume that the danger of future warfare is forever banished. The balance of power is no longer a factor. The balance of Nature has been partially restored. And only one problem remains to plague mankind." "What is that?" "We face extinction," Thurmon said. "But that's not true," Littlejohn interrupted. "Look at history and--" "Look at us." Thurmon sighed. "You needn't bother with history. The answer is written in our faces, in our own bodies. I've searched the past very little, compared to your scholarship, but enough to know that things were different in the old days. The Naturalists, whatever else they might have been, were strong men. They walked freely in the land, they lived lustily and long. "Do you know what our average life-expectancy is today, Littlejohn? A shade under forty years. And that only if one is fortunate enough to lead a sheltered existence, as we do. In the mines, in the fields, in the radioactive areas, they die before the age of thirty." Littlejohn leaned forward. "Schuyler touches on just that point in his _Psychology of Time_," he said, eagerly. "He posits the relationship between size and duration. Time is relative, you know. Our lives, short as they may be in terms of comparative chronology, nevertheless have a subjective span equal to that of the Naturalists in their heyday." "Nonsense," Thurman said, again. "Did you think that is what concerns me--whether or not we feel that our lives are long or short?" "What then?" "I'm talking about the basic elements essential to survival. I'm talking about strength, stamina, endurance, the ability to function. That's what we're losing, along with the normal span of years. The world is soft and flabby. Yardstick children, they tell us, were healthy at first. But _their_ children are weaker. And their grandchildren, weaker still. The effect of the wars, the ravages of radiation and malnutrition, have taken a terrible toll. The world is soft and flabby today. People can't walk any more, let alone run. We find it difficult to lift and bend and work--" "But we won't have to worry about such matters for long," Littlejohn hazarded. "Think of what's being done in robotics. Those recent experiments seem to prove--" "I know." Thurmon nodded. "We can create robots, no doubt. We have a limited amount of raw materials to allocate to the project, and if we can perfect automatons they'll function quite adequately. Virtually indestructible, too, I understand. I imagine they'll still be able to operate efficiently a hundred or more years from now--if only they learn to oil and repair one another. Because by that time, the human race will be gone." "Come now, it isn't that serious--"