They could see it was seaweed though it was woven into a wonderful fabric. Bernard and Kathleen and the Spangled Boy had somehow got seaweed dresses too, and the Spangled Boy was no longer dressed as a girl; and looking down as they scrambled up the steps Mavis and Francis saw that they, too, wore seaweed suits—“Very pretty, but how awkward to go home in,” Mavis thought. [Illustration: _The golden door._] “Now,” said the Mer-lady, “forgive me for taking the plunge. I knew you’d hesitate forever, and I was beginning to feel so cross! That’s your dreadful atmosphere! Now, here we are at the door of our kingdom. You do want to come in, don’t you? I can bring you as far as this against your will, but not any farther. And you can’t come any farther unless you trust me absolutely. Do you? Will you? Try!” “Yes,” said the children, all but Bernard, who said stoutly: “I don’t; but I’ll try to. I want to.” “If you want to, I think you _do_,” said she very kindly. “And now I will tell you one thing. What you’re breathing isn’t air, and it isn’t water. It’s something that both water people and air people can breathe.” “The greatest common measure,” said Bernard. “A simple equation,” said Mavis. “Things which are equal to the same thing are equal to each other,” said Francis; and the three looked at each other and wondered why they had said such things. “Don’t worry,” said the lady, “it’s only the influence of the place. This is the Cave of Learning, you know, very dark at the beginning and getting lighter and lighter as you get nearer to the golden door. All these rocks are made of books really, and they exude learning from every crack. We cover them up with anemones and seaweed and pretty things as well as we can, but the learning will leak out. Let us go through the gate or you’ll all be talking Sanskrit before we know where we are.” She opened the gate. A great flood of glorious sunlight met them, the solace of green trees and the jeweled grace of bright blossoms. She pulled them through the door, and shut it. “This is where we live,” she said. “Aren’t you glad you came?” CHAPTER SEVEN _The Skies Are Falling_ AS THE CHILDREN passed through the golden doors a sort of swollen feeling which was beginning to make their heads quite uncomfortable passed away, and left them with a curiously clear and comfortable certainty that they were much cleverer than usual. “I _could_ do sums now, and no mistake,” Bernard whispered to Kathleen, who replied to the effect that dates no longer presented the slightest difficulty to her. Mavis and Francis felt as though they had never before known what it was to have a clear brain. They followed the others through the golden door, and then came Reuben, and the Mermaid came last. She had picked up her discarded tail and was carrying it over her arm as you might a shawl. She shut the gate, and its lock clicked sharply.