“I know all that,” Perceveral said. “But I still don’t see why you stopped using the optimum explorer type.”

“Isn’t it obvious? We were looking for places where ordinary people could settle and survive. Our optimum explorer type was not ordinary. Quite the contrary, he almost approximated a new species. And he was no judge of ordinary survival conditions. For example, there are bleak, dreary, rain-swept little planets that the average colonist finds depressing to the point of insanity; but our optimum explorer is too sound to be disturbed by climatic monotony. Germs which devastate thousands give him, at most, a bad time for a while. Dangers which can push a colony to the brink of disaster, our optimum explorer simply evades. He can’t assess these things in everyday terms. They simply don’t touch him.”

“I’m beginning to see,” Perceveral said.

“Now the best way,” Haskell said, “would have been to attack these planets in stages. First an explorer, then a basic research team, then a trial colony composed largely of psychologists and sociologists, then a research group to interpret the findings of the other groups, and so forth. But there’s never enough time or money for all that. We need those colonies right now, not in fifty years.”

Mr. Haskell paused and looked hard at Perceveral. “So, you see, we must have immediate knowledge as to whether a group of ordinary people could live and thrive on any new planet. That’s why we changed our qualifications for explorers.”

Perceveral nodded. “Ordinary explorers for ordinary people. There’s just one thing, however.”