"Let us recast this in information theory terms," says the don. "Information flows from Germany to us, through the Ultra system at Bletchley Park. That information comes to us as seemingly random Morse code transmissions on the wireless. But because we have very bright people who can discover order in what is seemingly random, we can extract information that is crucial to our endeavors. Now, the Germans have not broken our important cyphers. But they can observe our actions—the routing of our convoys in the North Atlantic, the deployment of our air forces. If the convoys always avoid the U-boats, if the air forces always go straight to the German convoys, then it is clear to the Germans—I’m speaking of a very bright sort of German here, a German of the professor type—that there is not randomness here. This German can find correlations. He can see that we know more than we should. In other words, there is a certain point at which information begins to flow from us back to the Germans."