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here that belong to the genus we call Leptothrix, one of them should be an iron-fixing species. In all the millions of years that this planet has had life on it, that mutation must have occurred, and probably very early."
    "But why have we never seen it before? We have done perhaps more research in bacteriology than we have in any other field."
    "Because," Ruiz-Sanchez said earnestly, "you don't know what to look for, and because such a species would be as rare on Lithia as iron itself. On Earth, because we have iron in abundance, our Leptothrix ochracea has found plenty of opportunity to grow. We find their fossil sheaths by uncountable billions in our great ore beds. It used to be thought, as a matter of fact, that the bacteria produced the ore beds, but I've always doubted that. They get their energy by oxidizing ferrous iron into ferric-but that's a change that can happen spontaneously if the oxidation-reduction potential and the pH of the solution are right, and both of those conditions can be affected by ordinary decay bacteria. On our planet the bacteria grew in the ore beds because the iron was there, not the other way around-but on Lithia the process will have to be worked in reverse."
    "We will start a soil-sampling program at once," Chtexa said, his wattles flaring a subdued orchid. "Our antibiotics research centers screen soil samples by the thousands each month, in search of new microflora of therapeutic importance. If these iron-fixing bacteria exist, we are certain to find them eventually."
    "They must exist. Do you have a bacterium that is a sulphur-concentrating obligate anaerobe?"
    "Yes-yes, certainly!"
    "There you are," the Jesuit said, leaning back contentedly and clasping his hands across one knee. "You have plenty of sulphur, and so you have the bacterium. Please let me know when you find the iron-fixing species. I'd like to make a subculture and take it home with me when I leave. There are two Earth scientists whose noses I'd like to rub in it."
    The Lithian stiffened and thrust his head forward a little, as if puzzled.
    "Pardon me," Ruiz-Sanchez said hastily. "I was translating literally an aggressive idiom of my own tongue. It was not meant to describe an actual plan of action."
    "I think I understand," Chtexa said. Ruiz-Sanchez wondered if he did. In the rich storehouse of the Lithian language he had yet to discover any metaphors, either living or dead. Neither did the Lithians have any poetry or other creative arts. "You are of course welcome to any of the results of this program, which you would honor us by accepting. One problem in the social sciences which has long puzzled us is just how one may adequately honor the innovator. When we consider how new ideas change our lives, we despair of giving in kind, and it is helpful when the innovator himself has wishes which society can gratify."
    Ruiz-Sanchez was at first not quite sure that he had understood the formulation. After he had gone over it once more in his mind, he was not sure that he could bring himself to like it, although it was admirable enough. From an Earthman it would have sounded intolerably pompous, but it was evident that Chtexa meant it.
    It was probably just as well that the commission's report on Lithia was about to fall due. Ruiz-Sanchez had begun to think that he could absorb only a little more of this kind of calm sanity. And all of it-a disquieting thought from somewhere near his heart reminded him-all of it derived from reason, none from precept, none from faith. The Lithians did not know God. They did things rightly, and thought righteously, because it was reasonable and efficient and natural to do and to think that way. They seemed to need nothing else.
    Did they never have night thoughts? Was it possible that there could exist in the universe a reasoning being of a high order, which was never for an instant paralyzed by the sudden question, the terror of seeing through to the meaninglessness of action, the blindness of