We do not know the nature of light. Neither the undulatory theory nor the quantum theory are adequate to explain all observed phenomena, and they seem to be mutually exclusive, since it would seem clear by definition that no one thing can be at the same time continuous and discontinuous. We know nothing of the ether--we do not even know whether or not it exists, save as a concept of our own extremely limited intelligence. We are in total ignorance of the ultimate structure of matter, and of the arrangement and significance of those larger aggregations of matter, the galaxies. We do not know nor understand, nor can we define, even such fundamental necessities as time and space. Why prate of "the impossible"? Edward Elmer Smith, Ph.D. CHAPTER I DuQuesne Goes Traveling In the innermost private office of Steel, Brookings and DuQuesne stared at each other across the massive desk. DuQuesne's voice was cold, his black brows were drawn together. "Get this, Brookings, and get it straight. I'm shoving off at twelve o'clock tonight. My advice to you is to lay off Richard Seaton, absolutely. Don't do a thing. _Nothing, hold everything._ Keep on holding it until I get back, no matter how long that may be," DuQuesne shot out in an icy tone. "I am very much surprised at your change of front, Doctor. You are the last man I would have expected to be scared off after one engagement." "Don't be any more of a fool than you have to, Brookings. There's a lot of difference between scared and knowing when you are simply wasting effort. As you remember, I tried to abduct Mrs. Seaton by picking her off with an attractor from a space-ship. I would have bet that nothing could have stopped me. Well, when they located me--probably with an automatic Osnomian ray-detector--and heated me red-hot while I was still better than two hundred miles up, I knew then and there that they had us stopped; that there was nothing we could do except go back to my plan, abandon the abduction idea, and eventually kill them all. Since my plan would take time, you objected to it, and sent an airplane to drop a five-hundred-pound bomb on them. Airplane, bomb, and all simply vanished. It didn't explode, you remember, just flashed into light and disappeared, with scarcely any noise. Then you pulled several more of your fool ideas, such as long-range bombardment, and so on. None of them worked. Still you've got the nerve to think that you can get them with ordinary gunmen! I've drawn you diagrams and shown you figures--I've told you in great detail and in one-syllable words exactly what we're up against. Now I tell you again that they've _got something_. If you had the brains of a pinhead, you would know that anything I can't do with a space-ship can't be done by a mob of ordinary gangsters. I'm telling you, Brookings, that you can't do it. My way is absolutely the only way that will work." "But five years, Doctor!"