Often they passed other birds, even a bat or two, and strange, shimmering insects of monstrous size, and big, soft, stupid, graceful moths with wings of gray or green. The air seemed full of sounds,—the whirr of wings, the call of one flying thing to another, the rustling stir of the tree-tops, the low murmur of the wind, the laughing noise of running water underneath. Never had their ears been so busy. “Greeting, brother!” called Bizzybuzz to a big white owl that was flapping along beside them. But the owl said never a word. “He will not speak,” explained Bizzybuzz, flitting down to whisper, “because he is known as the wisest of all owls, and he is afraid that if he talks people will find out that he isn’t!” “Has the white owl anyone on his back?” asked Bab. “Look!” said Bizzybuzz, shooting up in the air once more. “He is still travelling beside us. He, like ourselves, is flying in the Wind Channel of Echoes. It is the best at this hour of the night.” They stood up to look. The white owl wore a collar of glittering silver, and on his back was sitting a wee old woman dressed all in white. “She is the Witch of Silence,” said Bizzybuzz. “She is very, very wise. She lives in a hollow tree, and the white owl sits outside and meditates. She is on her way now to the North Star, where there is a very learned oracle who can teach her some new spells.” “How will she get to the North Star?” asked Dick. “She will ride along the Wind Channel of Echoes until she reaches the North Star’s Ladder of Light, and then climb up, step by step. It will take her a hundred years.” “What in the world do you mean by Wind Channels and Ladders of Light?” demanded Meg, crossly. “You have roads on the ground in your country,” said Bizzybuzz. “_We_ have roads in the air. Isn’t that quite simple? We have the Wind Channel of Echoes and the Tree-Top Pathway and the Road of Clouds for times of storm; and the Moon-Wake when we want to cross the water and are too tired to fly. Sometimes we lose our way and have a dreadful time getting to shelter before daylight! As for the Ladder of Light, every star has a ladder leading straight up to it if only you can find it. The North Star is the hardest of all to reach, for it is so very far and cold, and the people there will receive only witches or air-spirits. They are very exclusive! The Witch of Silence will be welcome. She and the oracle will sit opposite each other for two hundred and seventy years, and then she will be truly wise, so she will climb down the Ladder of Light and go into her hollow tree again.” The white owl with the witch suddenly swerved off toward the right, and flapped away into the mists.