Cal leaned forward. Here was the spot where some student or apprentice might distinguish himself by asking an embarrassing question or so. Say the range of easily possible conditions on any given planet was a scale ten miles in length. Then that area on the scale where man could exist without artificial aids would still be less than a hair's breadth. And now to find a planet more nearly perfect for man than the one on which he evolved.... Or were the students considering this too obvious to mention? He decided to nudge them a little. Sometimes a discussion of the too obvious brought out things not obvious at all. "How frequently," he asked, when Hayes had cut him in, "do we find a mass revolving in such a manner that its poles revolve at right angles to its forward revolution, so there is no real pole?" "It requires near-perfect roundness, and an even distribution of land and water masses, such as we have on Ceti II," the first astrophysicist answered. "How frequently do we find that?" Cal repeated. "I know of no other," the astrophysicist replied shortly. "Any evidence of tampering with those ocean currents to get them flowing so beneficially?" Cal asked. "None yet discovered," an oceanographer cut in. Well, at least he hadn't stated with positiveness that there hadn't been and couldn't be. But an anthropaleontologist inserted himself and spoiled the effect of open-mindedness. "There is definitely no life form on Eden with sufficient intelligence for that," the man said, "nor has there ever been. Such a feat would require enormous engineering works. Such works under the ocean would be matched by comparable works on land, and would therefore show up in our aerial surveys, however ancient and overgrown." Cal sighed softly to himself. The human kind of civilization, yes, that would have left traces. But what of some other kind? Perhaps a deep-sea kind that had never come out upon the land? Never mind the arguments that such a civilization could not have developed--that was looking at it from the human point of view again. Had man grown so accustomed to not finding comparable intelligence anywhere in the universe he had begun to discount, or forget, there could be? The review went on and on. The zoologist sketched in the prevalent animals and fish forms, showed there was nothing in land animals higher than a large rodent, no sea mammals at all, no fish larger than the tarpon. Nothing at all to hint at a line of primates. A bacteriologist exclaimed at length over the similarity of minute life forms to those on Earth, and used the occasion to again expound the old theory of space-floating life spores to seed all favorable matter, and thus develop similar forms through evolution, wherever found. Quickly and tactfully Bill Hayes nudged him back on the track before the expected storm of controversy could break out.