Winter went on talking while I tried to assemble his fragmentary information into a coherent picture. A vast spider web of lines, each one a complete universe, each minutely different from all the others; somewhere, a line, or world, in which a device had been developed that enabled a man to move across the lines. Well, why not, I thought. With all those lines to work with, everything was bound to happen in one of them; or was it? "How about all the other A-lines, Winter," I said at the thought, "where this same discovery must have been made, where there was only some unimportant difference. Why aren't you swarming all over each other, bumping into yourself?" "That's been a big question to our scientists, old chap, and they haven't yet come up with any definitive answers. However, there are a few established points. First, the thing is a fantastically delicate device, as I've explained. The tiniest slip in the initial experimentation, and we'd have ended like some of those other lines you've seen photos of. Apparently the odds were quite fantastically against our escaping the consequences of the discovery; still, we did, and now we know how to control it. "As to the very close lines, theory now seems to indicate that there is no actual physical separation between lines; those microscopically close to one another actually merge or blend. It's difficult to explain. One actually wanders from one to another, at random, you know. In fact, such is the curious nature of infinity, that there seem to be an infinite number of infinitely close lines we're constantly shifting about in. Usually this makes no difference; we don't notice it, any more than we're aware of hopping along from one temporal point to the next as normal entropy progresses." At my puzzled frown he added, "The lines run both ways, you know, in an infinite number of directions. If we could run straight back along the normal E-line, we'd be travelling into the past. This won't work, for practical reasons involving two bodies occupying the same space, and all that sort of thing. The Maxoni principle enables us to move in a manner which we think of as being at right angles to the normal drift. With it, we can operate through 360 degrees, but always at the same E-level at which we start. Thus, we will arrive at Stockholm Zero Zero at the same moment we departed from B-I Three." Winter laughed. "This detail caused no end of misunderstanding and counter-accusation on the first trials." "So we're all shifting from one universe to another all the time without knowing it," I said skeptically.