l say, represents a two dimensional
creature. We lay him flatly against the desk, which represents
his world--Flatland, we mathematicians call it. Mr. Flatlander
can't see into our world. He can see only along the flat plane of
his own world. To see us, for instance, he would have to look
_up_, which is the third dimension, a direction inconceivable to
him. Now, Doctor, are you beginning to understand why we can
never see four dimensional beings?"

Pillbot frowned thoughtfully, then looked up. "And what about the
viewpoint of the four dimensioners themselves--_what would
prevent them from seeing us_?"

Harper hardly heard the Professor's snort of disgust. This two
dimensional cutout in "Flatland" fascinated him. An idea occurred
to him. Now, just supposing the....

* * * * *

As Gault and Pillbot argued, Harper grasped the paper cutout, and
bent it, "jacknifed" it, creasing it firmly in the middle. Then
he raised the upper half so that it rose vertically from the
desk, while the lower half was still pressed flatly against the
desk surface.

"Now," he murmured to himself, "the Flatlander would appear to
his fellows to have vanished from the waist up, because from the
waist up he is bent into the third dimension ... so far as they
are concerned...."

"E-e-e-e-e!"

At the wavering scream, Harper looked up quickly. Pillbot was
staring frozenly in front of him, toward the floor. Harper
followed his glance--and saw it.

Professor Gault had vanished from the waist up.

His lower body still stood before Pillbot, swaying slightly, but
the upper body was unconditionally missing. From the large feet
planted solidly on the floor, long legs rose majestically,
terminating in slim, angular hips--and from thence vanished
abruptly into nothingness. It was as though the upper body had
been sheared away, neatly and precisely, at the waist.

Pillbot stared from the visible portion of Gault to slack-jawed
Harper and back again, sweat splashing from his puffy face.

"Why, why really my dear fellow," he quavered, addressing the
half-figure. "This--this is a bit rude of you, vanishing in the
midst of my sentence. I--I trust you will--ah, return at once!"
Then, as the full import of the phenomenon penetrated to his
understanding, his eyes became glazed and he backed away.

The portion of Professor Gault addressed failed to give any
indication it had heard the remonstrance. Slowly, the legs began