Vertebrata and her mother, understanding little but trusting much, sat by his side. And together in the hot, white night the three watched the shadow of the stick travel on the dial that they had made. Of course there was no such thing as bed-time then, and Vertebrata usually sat up until she fell over asleep, when her mother carried her off to her little bed of skins; but this night she was so excited that she didn’t fall over. For the stick-shadow moved like a finger; like, indeed, a living thing that had been in the world all the time without their knowing. And they watched it while it went a long way round the circle. Then her mother said, “Nonsense, Vertebrata, you must be sleepy now whether you know it or not,” and she put her to bed, Vertebrata saying all the way that she was wide awake, just like in the daytime. And when her mother went back outside the cave, the Man looked up at her wonderfully. “Trachystomata,” said he (which is to say “siren”), “if the sun-shadow will do the same thing as the moon-shadow, we have found a way to make Vertebrata practise enough.” In the morning when Vertebrata came out of the cave--she woke alone and dressed alone, just like being grown-up--she found her mother and her father down on their hands and knees, studying the circle in the soft earth and the long sun-shadow of the stick. And her mother called her and she went running to her. And her mother said:-- “Now we will have breakfast, dear, and then you get your pipes and come here and practise. And when you begin, we will lay a piece of bone where the shadow stands, and when I feel the feeling of enough, I will tell you, and you will stop practising, and we will lay another piece of bone on that shadow. And after this you will always practise from one bone to another, forever.” Vertebrata could hardly wait to have breakfast before she tried it, and then she ran and brought her pipes and sat down beside the circle. And her father did not go to his hunting, or her mother to her cooking and cave-tidying, but they both sat there with Vertebrata, hearing her pipe and watching the shadow finger move, and waiting till her mother should feel the feeling of enough. _Now!_ Since the world began, the Hours, Minutes, and Seconds had been hanging over it, waiting patiently until people should understand about them. But nobody before had ever, ever thought about them, and Vertebrata and her mother and her father were the very first ones who had even begun to understand.