“Sit down, Leonard. I don’t want it to be gruesome. Strange, yes; there is nothing stranger, God knows, than this into which, frankly, I stumbled during my researches. I’ll try to make the fundamentals clear. It will lose its uncanny aspect then. You will find it all as coldly scientifically precise as your navigation of the Fortieth North parallel.” He lighted my cigarro. “This journey we are about to make,” he resumed, “involves but two factors. The first is the Eltonian principle of the neutralization of gravity. Sir Isaac Newton gave us fairly accurate formulae for the computation of the force of gravity. Einstein revised them slightly, and attempted to give an entirely different conception of celestial mechanics. “But no one—except by a rather vague theory of Einstein’s—has ever told us what gravity really is. What is this force—what causes this force—which makes every material body in the universe attract every other body directly in proportion to the mass and inversely as the square of the distance between them? “Leonard, I think I can make it clear to you. There is passing between every material body, one with another, a constant stream of minute particles. A vortex of rotating particles loses some on one side, which fly off at a tangent, so to speak, and perhaps gains some upon the other side. “Seventy-five years ago—about the time I was born, Leonard—they were talking of ‘electrons’, ‘radiant energy’, ‘positive and negative disembodied electricity.’ All different names for the same thing. The same phenomenon. “All substance is of a very transitory reality. Everything is in a constant state of change. A substance builds up, or it breaks down. Or both simultaneously; or sometimes one and then the other.” “Electricity—” I began. “Electricity,” he interrupted, “as they used to know it, is in reality nothing but a concentrated stream of particles—electrons, intimes, call them what you will—moving from one substance to join another. Lightning is the same thing. Such a stream of articles, Leonard, is a tangible manifestation of gravitational force. They had it right before them, unrecognized. They called it, ‘magnetic force,’ which meant nothing. “How do these streams create an attractive force? Conceive the earth and the moon. Between them flow a myriad stream of infinitesimal particles. Each particle in itself is a vortex—a whirlpool. The tendency of each vortex is to combine with the one nearest to it. “They do combine, collide, whirl together and split apart. The whole, as a continuous, violently agitated stream, produces a continuous tendency toward combination over all the distance from the earth to the moon. The result—can’t you see it?—must be a _force_, an inherent tendency pulling the earth and moon together.