Purnell crossed his long legs and spoke. "But you told me that your Zirthan guards made escape impossible. How did this fellow get away?" The warden grunted. "Excuse me, I said planned escape was impossible, and it is. Let a prisoner start making plans to get away and the guards are on to it at once. But this man made no plans. He was out on a work detail and saw a log floating down the river. In an instant he dived into the water and rode the log over the rapids. The guards fired at him but missed, and he made the rapids--they saw him still on the log below the white water. Impromptu action is still possible." "Pardon me," said Purnell, "I see how that would be. But where could he go? Isn't this planet just a prison colony for Earth?" "There are a few settlements," answered the warden. "Mostly space rats and prisoners whose terms have been served but who do not want to go back to Earth. And the space pirates have bases on some of the moons and contacts with the villagers. If he gets to a settlement they will hide him until the space pirates take him in. But he can't escape the mertha." * * * * * Purnell looked out the narrow window of the warden's office. The storm driving up the valley had reached them now and rain was beating fiercely against the plastic. He thought of the fugitive stumbling through the fury of the storm and of the two mertha coming closer and closer until the poor fellow's mind started cringing from the howling of these mental bloodhounds. He turned back to the warden. "I noticed that you ran the mentape through the machine but didn't show the men any pictures of the escaped man. Are they familiar with his looks?" "No. They have never seen the man, nor any picture of him." The warden paused to let this statement sink in, then went on before Purnell had a chance to speak. "There would be no use. The Zirthans cannot tell us apart by features. Not only do all of us humans look alike to them because we are alien, but they are not in the habit of using physical looks for such purposes. They have always used mental scanning for that. You notice the total lack of expression on their faces. Anger, hate, love, whatever emotion you think of, is expressed by a Zirthans thoughts, not by his facial expression. Telepathy has its advantages. Zirthans live in a world of mental calm and honesty that is unknown to us." The more Purnell thought about this the more he realized that it would be true. To a telepath the mind is an infinitely better source of information than the face would be. And just think, no physical disguise would be of the slightest use. "What if the man falls asleep? Can the mertha trace him then?" "Yes," replied the warden. "Thoughts go on in sleep, as when we dream. The mertha can't detect a man as far away when he is asleep, but an escaped prisoner does not go to sleep until he puts as great a distance between him and his prison as he can."