Groating said: "It will have to be done." "But there's an easier way," the controller cried. "I've been suggesting it all along. Let's attempt the trial and error method. We instigate a series of changes at once and see whether or not the future line is shifted. Sooner or later we're bound to strike something." "Impossible," Groating said. "You're suggesting the end of Stability. No civilization is worth saving if it must buy salvation at the price of its principles." I said: "Sir, I'd like to make a suggestion." They looked at me. The C-S nodded. "It seems to me that you're both on the wrong track. You're searching for a factor from the present. You ought to start in the future." "How's that?" "It's like if I said old maids were responsible for more clover. You'd start investigating the old maids. You ought to start with the clover and work backwards." "Just what are you trying to say, Mr. Carmichael?" "I'm talking about _a posteriori_ reasoning. Look, sir, a fella by the name of Darwin was trying to explain the balance of nature. He wanted to show the chain of cause and effect. He said in so many words that the number of old maids in a town governed the growth of clover, but if you want to find out how, you've got to work it out _a posteriori_; from effect to cause. Like this: Only bumblebees can fertilize clover. The more bumblebees, the more clover. Field mice attack bumblebee nests, so the more field mice, the less clover. Cats attack mice. The more cats, the more clover. Old maids keep cats. The more old maids ... the more clover. Q. E. D." "And now," Groating laughed, "construe." "Seems to me you ought to start with the catastrophe and follow the chain of causation, link by link, back to the source. Why not use the Prognosticator backwards until you locate the moment when the snowball first started rolling?" There was a very long silence while they thought it over. The controller looked slightly bewildered and he kept muttering: Cats--clover--old maids--But I could see the C-S was really hit. He went to the window and stood looking out, as motionless as a statue. I remember staring past his square shoulder and watching the shadows of the helios flicking noiselessly across the façade of the Judiciary Building opposite us. It was all so unreal--this frantic desperation over an event a thousand years in the future; but that's Stability. It's strictly the long view. Old Cyrus Brennerhaven of the _Morning Globe_ had a sign over his desk that read: If you take care of the tomorrows, the todays will take care of themselves. Finally Groating said: "Mr. Carmichael, I think we'd better go back to the Prog Building--"