ight 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."

"Not quite," contradicted Dr. Cloyd, still smiling. "To Mersey, my
patient, troubled by his delusion and using all his craft to persuade
both of us of its reality, the unsatisfactory answer would be the
satisfactory one."

* * * * *

Mersey's voice laughed. "Dr. Cloyd, I salute you. I will leave your
world with a tremendous respect for you--and completely unsure of
whether you believe in my existence."

"Thank you."

"I am leaving, you know," Mersey's voice replied.

The traveler by now was resigned to letting the patient be his medium
and speak his thoughts. Thus far, he had spoken them all truly, if
somewhat excessively. The traveler thought he knew why, now, and
expected Mersey to voice the reason for him very shortly. He did.

"I'm leaving because I must report failure and advise my people to
look elsewhere for a new home. Part of the reason for that failure I
haven't yet mentioned:

"Although it might appear that I, the visitor, am manipulating Mersey
to speak the thoughts I wished to communicate, the facts are almost
the opposite. My control over either Mersey's body or mind is
practically nil.

"What you have been hearing and what you hear even now are the
thoughts I am thinking--not necessaril