"I have tried to teach you much, Arnoldi," he said, "but a complete knowledge of the science of infinite dimensions is too broad for one man. Our span of life is too short--the powers of apprehension too limited. Yet I mean just what I say about the planes of vision and hearing. I will go even further. I believe there are living material things on these other planes. It will surprise you, no doubt, to learn that I have created a medium through which we may see and hear them!" I stared at him astounded--fascinated. He smiled down at me with supreme assurance, but without the arrogance that usually accompanies such statements of scientific power. Yet the conception of such a thing was too stupendous for me to grasp all at once. At the moment I could relieve my tension in no way but to laugh. My mirth seemed to sober him and his features clouded. I felt suddenly ill at ease under his steady eyes and became more serious. "I'm sorry, sir," I said, grasping his sleeve. "I couldn't help but laugh at the conception. But I simply can't grasp the feasibility of such a thing. It sounds too much like Valenev." "Arnoldi," he replied impressively, "as we see it the world has been fairly well explored. Yet, if we were to delve into the hidden worlds around us, think of the strange objects and beings that might be seen. Why, the value of the knowledge that could be gleaned from such an adventure would be beyond calculation!" My head spun at the thought and I stood erect, eager with anticipation. "You almost convince me, sir," I said, "that such a thing can be done--that such worlds do actually exist." "It _can_ be done, Arnoldi," he replied, smiling again: "And other worlds _do_ exist within our own world! It is possible that we can visit at least several of them. Would you like to see them, my son?" Trembling I nodded assent. Dr. Korsakoff grasped my shaking hand and wrung it in a firm grip. He placed an arm around me and together we strode slowly toward the laboratory. As we entered the work-shop which contained practically every known instrument of optical science, and many others, including high-speed lathes, grinding apparatus, measuring devices for facet shaping, and priceless stores of transparent gem-stones, I had a vague feeling that the experiment would see the advent of something unknown to man. I cast a glance at the scientist. His face was stern and serious, although his eyes glowed with excitement. But, could I have realized then what the experiment was to lead to!