"The environment is what destroys, is what weakens, is what kills. Call it a blast furnace. Call it disease. Call it a clawing tiger. It is, nevertheless, our environment: temporary or permanent. To survive that, man must be immortal, in a physical sense. In the sense that he possesses _in himself_ all the necessary attributes to enable him to overcome that environment. That way lies immortality." Dr. Wooden regarded the glowing tip of his cigarette. He said, "That's clear enough. It is fantastic, but who knows what changes one million or two million years will bring in man. Lord knows, it brought a lot of changes on Earth itself! Now, about the flames--" Jonathan crushed out his cigarette. "They were the emanations from the calcatryte. I realized that eventually. It stood to reason. It had to be something alien to a universe where light curves. Something that either ate up matter or made it invisible or opened a door for it to leak out somewhere, into nothingness. "Calcatryte gives off straight light, so powerful that it eats through metal. It could as easily eat through dirt and rock, through the moon of a planet, through a planet itself. Through the universe, in short. In a universe based on curving light, that unbendable light was an anomaly. It ate up our universe, or started to." "Again, clear enough. It's reasonable, and possible. But when you went into the shadows and passed through them--you emerged here in my laboratory. But my laboratory is billions upon billions of miles from Neeoorna." Jonathan grunted, "In terms of ordinary space, yes. I passed through hyperspace." "That's a mathematical concept." "I know. But we--you have proved it exists. It has been proven mathematically." Dr. Wooden looked dubious. Jonathan picked up a pencil and pressed down with the point on a slip of graph paper. "That black mark, that dot, is one-dimensional. Extend a line from that point to another dot. The line is also one-dimensional. Let us put the pencil on the line, supersede the line with the pencil. Since the pencil has three dimensions, so does the line--for the pencil is the line. "Suppose an _n_-dimensional object. Supersede the pencil with the _n_-dimensional object and we have an _n_-dimensional line. It is an _n_-dimensional space of _n_-dimensional points, instead of our original definition of a line as a single dimensioned space of points set in a row. "Ordinary space is called three-dimensional because it is occupied by three-dimensional things. Planes, for instance. But if we speak of lines of spheres or circles, we can easily step into the realm of _n_-dimensionality. "The drawback is that we can't see it. We can't envision _n_-dimensionality.