“No!” he exclaimed warmly. “There is where you fail to grasp my fundamental conception. The void of space itself is a mass of particles, a mass of densities, of every possible size and character. “The earth is one; a wandering asteroid is another. And meteors, meteorites, down to the smallest particles of dust. And still smaller, are the particles of light, far flung everywhere through space. Other entities are again still smaller—call them intimes—down in size to infinity. “Space then, you must realize, is not empty. The emptiness, the nothingness, is only the infinitely small. Ah, I see now that you begin to understand!” I said slowly, “I’m imagining space as . . . as a jelly. Unsolid, because we ourselves are more solid, and it seems unsolid to us. But . . . if we were less dense, and larger . . . gigantic—” I stopped. “That,” said Dr. Weatherby, “is precisely the point of view I’ve wanted you to get. You can understand now why to beings of some greater outside realm all our interstellar space would shrink into apparent solidity, and they would call it an atom. * * * * * “Conceive yourself now a scientist of that vast universe outside. You are living on a density—a great conglomeration of particles clinging together—and you call it your earth. “One tiny particle of your earth is beneath your microscope. You call that particle a grain of gold. You examine it. You find it is not solid. You see ‘empty spaces.’ They are not really empty, but the particles of matter swimming in them are too small for you to see. But you do see what you call molecules of gold. “You increase the power of your microscope. You examine just one molecule of this gold. Now you see more supposedly empty spaces, with smaller whirling entities which you choose to call atoms. “You examine one atom. The same result and you call the still smaller particles electrons. Down and down—who can say how far? Until, at last, you are looking into one intime. You see yet smaller particles whirling in space. That is the space between our stars! “And these whirling points of light—perhaps you can distinguish no more than a million of them. They are the million largest, brightest of our stars. You cannot see our own sun; it is too small. Or our earth—too small. And too dark. “But if you did see our earth, and were a fatuous scientist, you might say, ‘Ah, at last I have seen the _smallest thing_!’ Which is amusing, because our earth has a good many rocks composing it. And each rock goes down to pebbles, grains of sand, molecules, atoms, electrons—to infinity. “Do you get the conception now? This whole universe we see and feel from here on earth, from a greater viewpoint would all shrink into a tiny, apparently solid particle.” “I can visualize it,” I said. “It’s stupendous.” But Jim interposed, “This trip we are to make—”