lism--no?--the one who
argues that we do not see, feel, hear, taste the object, but that we
have only the sensation of seeing, feeling, hearing, tasting."

"I--sort of recall it."

"Hah! But sensations are _mental_ phenomena. They exist in our minds.
How, then, do we know that the objects themselves do not exist only in
our minds?" He waved again at the light-flecked buildings. "You do not
see that wall of masonry; you perceive only a _sensation_, a feeling of
sight. The rest you interpret."

"You see the same thing," retorted Dan.

"How do you know I do? Even if you knew that what I call red would not
be green could you see through my eyes--even if you knew that, how do
you know that I too am not a dream of yours?"

Dan laughed. "Of course nobody _knows_ anything. You just get what
information you can through the windows of your five senses, and then
make your guesses. When they're wrong, you pay the penalty." His mind
was clear now save for a mild headache. "Listen," he said suddenly. "You
can argue a reality away to an illusion; that's easy. But if your friend
Berkeley is right, why can't you take a dream and make it real? If it
works one way, it must work the other."

The beard waggled; elf-bright eyes glittered queerly at him. "All
artists do that," said the old man softly. Dan felt that something more
quivered on the verge of utterance.

"That's an evasion," he grunted. "Anybody can tell the difference
between a picture and the real thing, or between a movie and life."

"But," whispered the other, "the realer the better, no? And if one could
make a--a movie--_very_ real indeed, what would you say then?"

"Nobody can, though."

The eyes glittered strangely again. "I can!" he whispered. "I _did_!"

"Did what?"

"Made real a dream." The voice turned angry. "Fools! I bring it here to
sell to Westman, the camera people, and what do they say? 'It isn't
clear. Only one person can use it at a time. It's too expensive.' Fools!
Fools!"

"Huh?"

"Listen! I'm Albert Ludwig--_Professor_ Ludwig." As Dan was silent, he
continued, "It means nothing to you, eh? But listen--a movie that gives
one sight and sound. Suppose now I add taste, smell, even touch, if your
interest is taken by the story. Suppose I make it so that you are in the
story, you speak to the shadows, and the shadows reply, and instead of
being on a screen, the story is all about you, and you are in it. Would
that be to make real a dream?"

"How