"Your proof," Dr. Pillbot broke into his thoughts insistently, "is purely negative, Professor! How can you know there are no beings in the fourth dimension, unless you actually enter this realm, to see for yourself?"
Professor Gault stared at the fat, puffy face of his visitor, and snorted loudly.
"I am afraid, Pillbot, you do not comprehend the impossibility of such a passage. We can not possibly break from the confines of our three dimensional world. Here, let me explain by a simple illustration."
Gault took up a book, held it so that a shadow fell onto the surface of the desk.
"That shadow," he said, "is two dimensional, has length and breadth, but no thickness. Now in order to enter the third dimension, our plane, the shadow would have to bulge out in some way, into the dimension of thickness an obvious impossibility. Similarly, we can not enter the fourth dimension. Do you see?"
"No!" retorted Pillbot with some heat. "In the first place, we are not two dimensional shadows, and—why, what is the matter?"
Professor Gault's lanky form had stiffened, his near sighted eyes glaring out over the laboratory to the rear of Pillbot. The psychiatrist wheeled around, followed his host's gaze.
It was Harper. That young man's antics drew an amazed grunt from Pillbot. He was describing peculiar motions in the air with his pencil. Circles, whorls, angles, abrupt jabs forward. He bent over the paper on the desk, made a few sweeps of the pencil, then the pencil rose again into the air to describe more erratic motions. Harper himself seemed in a trance.
Suddenly Pillbot gave a stifled gasp. It seemed to him that Harper's arm vanished at the elbow as it stabbed forward, then reappeared. Once again the phenomenon happened.
Pillbot blinked rapidly, rubbed his eyes. It must have been illusion, he decided. It was too ... unlikely....