Dr. Cloyd paused. Mersey had no immediate reply. The traveler made use of the silence to consider this plausible, but frightening theory. To accept the theory would be to accept a destiny of madness here on this world, although the doctor had been kind enough to draw a distinction between madness in one dimension and a mere lack of natural balance in another. Mersey again seized upon the traveler's mind and spoke its thoughts. But as he spoke, he voiced a conclusion which the traveler had not yet admitted even to himself. "Then the answer is inescapable," Mersey said, his tone flat and unemotional. "It is theoretically possible for all of our people to migrate to this world and find refuge of a sort. But if we established ourselves in the minds of your normal people, we'd be without will. As mere observers, we'd become assimilated in time, and thus extinguished as a separate race. That, of course, we could not permit. And if we settled in the minds most suitable to receive us, we would be in the minds of those who by your standards are insane--whose destiny is controlled by the others. Here again we could permit no such fate. "That alone would be enough to send me back to my people to report failure. But there is something more--something I don't think you will believe, for all your ability to synthesize acceptance of another viewpoint." "And what is that?" "First I must ask a question. In speaking to me now, do you still believe yourself to be addressing Mersey, your fellow human being, and humoring him in a delusion? Or do you think you are speaking through him to me, the inhabitant of another world who has borrowed his mind?" * * * * * The doctor smiled and took time to relight his pipe. "Let me answer you in this way," he said. "If I were convinced that Mersey was merely harboring a delusion that he was inhabited by an alien being, I would accept that situation clinically. I would humor him, as you put it, in the hope that he'd be encouraged to talk freely and perhaps give me a clue to his delusion so I could help him lose it. I would speak to him--or to you, if that were his concept of himself--just as I am speaking now. "On the other hand, if I were convinced by the many unusual nuances of our conversation that the mind I was addressing actually was that of an alien being--I would still talk to you as I am talking now." The doctor smiled again. "I trust I have made my answer sufficiently unsatisfactory." The visitor's reaction was spoken by Mersey. "On the contrary, you have unwittingly told me what I want to know. You'd want your answer to be satisfactory if you were speaking to Mersey, the lunatic. But because you'd take delight in disconcerting me by scoring a point--something you wouldn't do with a patient--you reveal acceptance of the fact that I am not Mersey. Your rules would not permit you to give him an unsatisfactory answer."