I must have stammered my thoughts aloud, for Will said, "What we see, and what really exists, has puzzled metaphysicians for centuries. Who knows what this thing really looks like? You do not, nor do I. Our minds are capable of visualizing things only within the limits of an accustomed mould. You see that thing as a man of fairly human aspect, and so do I. The details are elusive; but stare at them for a day and your imagination will supply them all. That's what you do in infancy with the whole material world about you--mould it to fit our human perceptions. But what everything really looks like--who can tell?" "Can it--can it hear us?" I demanded. "No--I do not think so. It can see us, no more. And it has no fear." With a belligerent gesture he added humorously, "Get up, you, or I'll wring your neck!" "Will, don't joke like that!" Bee protested. He turned away and switched on the main lights. I could still see the thing there, but now it was paler--wan like starlight before the coming dawn. Will turned his back on it and sat down. His face had gone solemn again. "These things are materializing, Rob. They have become a menace. That's why what I'm planning to do should be done at once.... Bee! Will you please not interrupt me!" It was the first time I had ever heard his tone turn sharp with her, and I realized then the strain he was under. "Rob, listen to me. Science has given me the power to do what I'm planning, but we won't discuss that now. Call this anything you like. What I want you to know is--there is another realm about us into which--under given conditions--our consciousness can penetrate. Call it the Unknown. The realm of Unthought Things. A material world? I've shown you, Rob, that nothing is substance if you go to the inside of it." Dimly I was groping at a hundred will-o'-the-wisps, my mind trembling upon the verge of his meaning, my imagination winging into distant caverns of unthought things that hid in the elusive dark. Could this be science? He was saying, "My mind cannot fathom such another realm, nor can yours. You think of land, water, trees, houses, people. Those are only words for what we think we see and feel. But there are beings--sentient beings--in this other state of consciousness, we can now be sure. For Rob, they are coming out! Don't you understand? They have already come into the borderland between the consciousness of their realm and ours." He would not let me interrupt him. "Wait, Rob! Let us say they have a lust for adventure--or a lust for something else--they are coming out nevertheless. A menace to us--that girl in Kansas is dead." He swept his hand in gesture at the apparition behind him. "That thing is watching me. As Bee says, it is on guard here. Because, Rob, I found a way of transmuting my identity out of this conscious realm of ours into that same borderland where these things we call ghosts are roaming. And they know it--and so they're on guard--watching me."