"It would be ridiculous," he began, after several thoracic bifurcations, "for me to explain myself more fully to you. Unless you had a clock you couldn't possibly understand. But I hope I have made it clear that my world is a multiform world. It has a thousand manifestations as compared to one of yours. It is a world of many dimensions, and every dimension is crowded with people and things. Only they don't get in each other's way, like you do, because there are always other dimensions at hand." "That I can follow," said the Doctor, wrinkling his brows, "that seems to me fairly clear. I can just grasp that, as the hypothesis of another sort of world. But what I don't understand, what I can't begin to understand, is how you work, how this mechanism which you talk about functions." He delivered this last sentence rather in the manner of an ultimatum, and the Clockwork man seemed to brood over it for a few seconds. He was apparently puzzled by the question, and hard mechanical lines appeared upon his forehead and began slowly chasing one another out of existence. It reminded the Doctor of Venetian blinds being pulled up and down very rapidly. "Well," the reply was shot out at last, "how do _you_ work?" The repartee of the Clockwork man was none the less effective for being suspended, as it were, for a second or two before delivery. The doctor gasped slightly and released his hold upon a mustard pot. He came up to the rebound with a new suggestion. "Now, that's a good idea. We might arrive at something by comparison. I never thought of that." He grasped the mustard pot again and tried to arrange certain matters in his mind. "It's a little difficult to know where to begin," he temporised. "Begin at the end, if you like," suggested the Clockwork man, affably. "It's all the same to me. First and last, upside or inside, front or back--it all conveys the same idea to me." "We are creatures of action," hazarded the Doctor, with the air of a man embarking upon a long mental voyage, "we act from certain motives. There is a principle known as Cause and Effect. Everything is related. Every action has its equal and opposite re-action. Nobody can do anything, or even think anything, without producing some change, however slight, in the general flow of things. Every movement that we make, almost every thought that passes through our minds, starts another ripple upon the surface of time, upon this endless stream of cause and effect."