pe I don't."

Camberton said: "I'll try to explain in words, Senator. They're
inadequate, but a fuller explanation will come later."

And he launched into the story of the two-decade search of Paul Wendell.

CODA--ANDANTINO

"Telepathy? Time travel?" After three hours of listening, the
ex-President was still not sure he understood.

"Think of it this way," Camberton said. "Think of the mind at any given
instant as being surrounded by a shield--a shield of privacy--a shield
which you, yourself have erected, though unconsciously. It's a perfect
insulator against telepathic prying by others. You feel you _have_ to
have it in order to retain your privacy--your sense of identity, even.
But here's the kicker: even though no one else can get in, _you_ can't
get out!

"You can call this shield 'self-consciousness'--perhaps _shame_ is a
better word. Everyone has it, to some degree; no telepathic thought can
break through it. Occasionally, some people will relax it for a fraction
of a second, but the instant they receive something, the barrier goes up
again."

"Then how is telepathy possible? How can you go through it?" The Senator
looked puzzled as he thoughtfully tamped tobacco into his briar.

"You don't go _through_ it; you go _around_ it."

* * * * *

"Now wait a minute; that sounds like some of those fourth dimension
stories I've read. I recall that when I was younger, I read a murder
mystery--something about a morgue, I think. At any rate, the murder was
committed inside a locked room; no one could possibly have gotten in or
out. One of the characters suggested that the murderer traveled through
the fourth dimension in order to get at the victim. He didn't go through
the walls; he went around them." The Senator puffed a match flame into
the bowl of his pipe, his eyes on the younger man. "Is that what you're
driving at?"

"Exactly," agreed Camberton. "The fourth dimension. Time. You must go
back in time to an instant when that wall did not exist. An infant has
no shame, no modesty, no shield against the world. You must travel back
down your own four-dimensional tube of memory in order to get outside
it, and to do that, you have to know your own mind completely, and you
must be _sure_ you know it.

"For only if you know your own mind can you communicate with another
mind. Because, at the 'instant' of contact, you _become_ that person;
you must enter his own memory at the beginn