believe what he was hearing.

"How'd you get all this stuff? In dreams?"

Chalmers shook his head. "It just came to me. I'd be sitting reading,
or eating dinner, or talking to one of my classes, and the first thing
I'd know, something out of the future would come bubbling up in me. It
just kept pushing up into my conscious mind. I wouldn't have an idea
of something one minute, and the next it would just be part of my
general historical knowledge; I'd know it as positively as I know that
Columbus discovered America in. 1492. The only difference is that I
can usually remember where I've read something in past history, but my
future history I know without knowing how I know it."

"Ah, that's the question!" Weill pounced. "You don't know how you know
it. Look, Ed, we've both studied psychology, elementary psychology at
least. Anybody who has to work with people, these days, has to know
some psychology. What makes you sure that these prophetic impressions
of yours aren't manufactured in your own subconscious mind?"

"That's what I thought, at first. I thought my subconscious was just
building up this stuff to fill the gaps in what I'd produced from
logical extrapolation. I've always been a stickler for detail," he
added, parenthetically. "It would be natural for me to supply details
for the future. But, as I said, a lot of this stuff is based on
unpredictable and arbitrary factors that can't be inferred from
anything in the present. That left me with the alternatives of
delusion or precognition, and if I ever came near going crazy, it was
before the _Kilroy_ landed and the news was released. After that, I
knew which it was."