There was a period of bewilderment, almost panic, in which they both felt so physically weak that they had to sit down on the concrete and stare at each other mutely. But this passed and their natural courage soon reasserted itself. Their first thought was to take stock of what information they could get on their situation; and their first step was to venture as close as possible to the queer little horizon which lay almost at their very feet. It gave them a frightened feeling, as though they were standing high up on a precipice or tower. To their surprise, the horizon receded as they walked toward it, always remaining about a dozen feet away from them. At first they walked on concrete and then came to a crumbly edge of it and found themselves stepping on hard, sandy earth. Later there was rock, sometimes granite-like, sometimes black and shiny. But what they saw underfoot was nothing, compared with the glimpses of things they got out in the surrounding emptiness. First there was a vast space in which a soft light shone, and in which there were countless spheres of various sizes, motionlessly suspended. The spheres seemed to be made of wood, a green, sap-filled, unseasoned wood. The scene was visible for a few seconds, and vanished suddenly as they walked on. This astonished them; so they stepped back a pace or two and saw it again; and as they moved on, it disappeared again. * * * * * Then there was a great stretch of water in which the backs of huge monsters rolled and from which a hot wind blew for a few instants until they passed on and the scene vanished. There was a short walk with nothing but emptiness, and then there appeared huge, oblique, cubistic looking rows of jagged rocks in wild, dizzy formations that didn't look possible; and farther on, after another interval of emptiness, a tangle of brown, ropey vines with black-green leaves on them, an immense space filled with serpentine swinging loops and lengths of innumerable vines. Several loops projected so near them that they could have reached out and touched them had they wished. "This is too much for me!" Phil gasped. "Have we gone crazy? Or did he kill us, and is this Purgatory?" Ione smiled and shook her little head in which she had a goodly store of modern mathematics stored away. "These must be glimpses of other 'spaces' besides our own space. If we could see in four dimensions we could see them all spread out before us. But we can only perceive in three dimensions; therefore, as we walk through hyperspace, past the different 'spaces' which are ranged about in it, we get a glimpse into such of them as are parallel with our own space. Can you understand that?" "Oh, yes," groaned Phil. "It sounds just about like it looks. But, don't mind me. Go on, have your fun."