“But there are certain links,” he added, “which bind both worlds together, and two of these are known to you as _light_ and _gravity_. Our world is for ever in motion; motion is of the essence of its being, and it communicates its motion to all that is formed out of it and continued by it as your worlds are. Such motion is communicated in exact proportion to the vastly varied complexities of the matter of your worlds, and out of this proportionate communication arise the movements and the laws of movement of all the stars and planets, all of which movements and laws of movement are amenable to calculation. Much of this is already known to you, and the day will probably come when your men of science will be able to calculate the proper motion of the remotest star that your instruments can discover with as much precision as they now calculate the motions of your moon. “Light is another link between your worlds and ours. And light is the one means which we have of detecting from our world the presence of yours. Not that we see light as you see it. The sort of perception that you have by means of light we have in our world by analogous but higher means. The presence of light is known to us when in our own world only by a slight shuddering motion of the ether. Just as you perceive a difference in the mode of motion when you travel on land and on the water or in the air; just so we perceive an analogous difference when we pass to the regions of light from the regions where light is not. A shuddering motion of the material of our world warns that we are where your worlds are. And just as for you sometimes the motion of the air or water passes into a hurricane or a whirlpool, so to us a vastly increased movement of the ether (not the regular movement which is the cause of gravity, but a quivering movement) indicates the presence of one of the secular outbursts of conflagration which form part of the process by which your worlds become fitted for your occupation.” “But how,” inquired I, “can you come into our world without having any direct sensation of its whereabouts?” “Once we have been here,” he said, “it is a matter of easy calculation to us to fix the locality; and we can communicate the elements of the calculation to others who have not been here.” Here he paused, and rose to his feet, and as we were about to rise he signed to us to keep sitting. “Now,” he said, “hearken carefully while I tell you of those into whose power you are fallen.” And as he spoke it seemed to me that his attention was directed more especially to myself. He went on—“The Infinite One, ages before your worlds were formed, called the ethereal host into being. And at first they were like your brute creatures, only with vastly greater powers and intelligence; yet, like them, for their vast powers were not under the control of any will of their own, for there was no such thing then as will, except the will of the Infinite One.