"But more specifically, what is it? Somehow I cannot imagine--" "You see ... how shall I put it? Are you a mathematician?" "Yes." "Then you see ... imagine a plane, let us say this mirror. You and I are on its surface. You see? there we are, squinting our eyes to protect ourselves from the sunlight, or here is the bluish electric spark in that tube, there the shadow of that aero that just passed. All this is on the surface, is momentary only. Now imagine this very same surface softened by a flame so that nothing can any longer glide over it, so everything instead will penetrate into that mirror world which excites such curiosity in children. I assure you, children are not so foolish as we think they are! The surface becomes a volume, a body, a world; and inside the mirror,--within you, there is the sunshine, and the whirlwind caused by the aero propeller, and your trembling lips and someone else's lips also. You see, the cold mirror reflects, throws out, while this one absorbs; it keeps forever a trace of everything that touches it. Once you saw an imperceptible wrinkle on some one's face, and this wrinkle is forever preserved within you; you may happen to hear in the silence a drop of water falling,--and you will hear it forever!" "Yes, yes, that is it!" I grasped his hand. I could hear drops of water dripping in the silence from the faucet of a washstand and at once I knew it was forever. "But tell me please, why suddenly ... suddenly a soul? There was none, yet suddenly.... Why is it that no one has it, yet I...." I pressed the thin hand; I was afraid to loosen the safety belt. "Why? Well, why don't we grow feathers or wings, but only shoulder blades, bases for wings? We have aeros; wings would only be in the way. Wings are needed in order to fly, but we don't need to fly anywhere. We have arrived at the terminus. We have found what we wanted. Is that not so?" I nodded vaguely. He glanced at me and laughed a scalpel-like metallic laugh. The other doctor overheard us and stamped out of his room on his heavy legs. He picked up the thin doctor with his horn-eyes, then picked me up. "What is the matter, a soul? You say a soul? Oh, damn it! We may soon retrogress even to the cholera epidemics. I told you," he tossed the thin one on the horns, "I told you the only thing to do is to operate on them all, wholesale! simply extirpate the centre for fancy. Only surgery can help here, only surgery." He put on a pair of enormous X-ray spectacles and remained thus for a long while, looking into my skull, through the bones into my brain and making notes. "Very, very curious! Listen." He looked firmly into my eyes. "Would you not consent to have me perform an extirpation on you? It would be invaluable to the United State; it might help us to prevent an epidemic. If you have no special reasons, of course...."