Phil nodded joyfully; an old sailor had taught him during a long happy summer he had spent by the sea, and had been quite proud of his pupil. "Not that it would matter if you had never learnt," said Mother Beaver, struck by a sudden thought, "for Nature has made you an exception to all her rules. What is an exception? Well, you must wait until Father Beaver comes if you want it properly explained, but it means that while you are Nature's guest you will be able to do all those things that a small boy _wouldn't_ be able to do in the usual way; such as breathe under water, for instance, as you will in a moment, when you come to my winter home. You will change your size, too, without knowing anything about it, just when and where it is most convenient, so that you can sit in nests, or run down burrows, as easily as the creatures to which they belong. And you'll never feel hungry, unless there is something near that you can eat, or thirsty, unless you are within easy distance of a stream. In short, my dear, Nature has been particularly kind to you for this one year; after that you'll be just an ordinary boy again." Phil was rather bewildered; it sounded much too wonderful to be true, but Mother Beaver, seemed quite in earnest. "Are you ready?" she said. "Then follow me. We're going to my winter lodge, where my young ones are still waiting for me. Their father and I only left it this morning to look round, for spring comes suddenly here in the north, and a day or two ago it was quite cold. The flowers are in bloom, the Bees say, before they have time to notice their buds, and the trees spread out their leaves in a single night. The winter has only just gone." Phil followed her to the water's edge through clumps of rushes, and saw before him a cluster of dome-shaped houses, like giant thimbles, in the centre of the stream. Many were some feet above the surface of the water; they were covered with a smooth coating of hard mud, and so far as he could see they had no entrance. "Did you make those?" he asked, as she led him on to the dam, so that he might get a better view of them. He was amazed that such an insignificant creature as the beaver could build such fortresses. "Of course we did," she answered in matter-of-fact tones. "Yes--they took a long time, but we worked together, and worked with a will. The walls, you'll notice, are more than six feet thick. They have to be very strong," she added mysteriously. Phil wanted to ask her why, but she seemed so troubled that he said "How do you get in?" instead. "Take a header and see," she told him, splashing from the dam and diving straight down, with Phil behind her, until they reached the deep projection, or "angle" as it is called, beneath which lay the entrance to her own particular home. It was very near the bed of the river, where the frost would not be likely to reach even in bitter weather.