"That's what Aunt Mary said; I heard her talking. That's why I read about it, because I'm fairly good at maths. She has it all pasted in a book. I had to skip most of it, but here and there I found bits. I took some notes," Mollie drew a penny notebook from her pocket. "One man says that, if the world travelled as fast as light, there would be no Time. All the clocks would stop, and we'd be There as soon as we were Here. Well now, that's just what we did. We were Here--and we were There. So our time stopped and Now was Then. See?" "He says _If_. You couldn't live without Time. You _must_ have Time to do things in or where would you be? You'd have to swallow all the meals of your life at one mouthful and you'd bust. What comes next?" "Another man says," Mollie read impressively, "that any schoolboy--_any_ schoolboy," she repeated, fixing a stern eye upon her brother, "can see that, if the velocity of light has a given value with reference to the fixed stars, it cannot have the same value with reference to its source when this is moved relatively to the stars." "Gee-whiz!" said Dick. "Next, please." "A man says that perhaps things measured north and south are different from things measured east and west. _We_ travelled north and south. Perhaps we stretched back in Time all of a sudden, like elastic." "Couldn't be done. Elastic stretches both ways. If _you_ tried to move north and south both at the same time you'd go off like a Christmas cracker. Next." "A man says that our ideas of space and time may be all wrong." "Aunt Polly will agree with him if we stand here much longer," said Dick. "Next. Hurry up." "You don't stop to _think_," Mollie said impatiently. "Try and _think_. Your head might just as well be a football. What _I_ think is that if two un-understandable things are discovered about the same time they must belong to each other. Don't you see _that_?" "They might," Dick said cautiously, "and then again they mightn't. I don't think myself that there's any use trying to understand things like Time-travelling and Relativity. People like us never will." "I don't know that," said Jerry, who had been listening to the discussion in silence. "There's lots of things just as hard to understand, only you take them for granted. Being alive, for instance. Look at Mollie fidgeting about, and Long John chewing and twitching, and the trees waving their branches, and you shaking your head as if it were a dinner-bell, which is about what it is--it's all life. Just as hard to understand as Relativity, and a jolly sight harder if you ask me. I can't say I understand Time-travelling, but--" Jerry broke off. Mollie frowned thoughtfully. "We don't understand it _yet_," she said, "but in _another_ forty years--" They were all silent. Another forty years!