“Yes,” it said, “perhaps you could. Human children can open books, I believe. Porpoises can’t. And Mer-people can’t open the books in the Cave of Learning, though they can unlock them. If they want to open them they have to get them from the Public Mer Libraries. I can’t help knowing that,” it added. The Porpoises seemed really ashamed of not being thoroughly stupid. “Come on,” said Francis, “we’ll raise an army to fight these Book People. Here’s something we can do that _isn’t_ mischief.” “You shut up,” said Bernard, and thumping Cathay on the back told her to never mind. They went toward the golden gate. “I suppose all the nasty people are out of the books by now?” Mavis asked her Porpoise, who followed her with the close fidelity of an affectionate little dog. “_I_ don’t know,” it said, with some pride. “I’m stupid, I am. But I can’t help knowing that no one can come out of books unless they’re called. You’ve just got to tap on the back of the book and call the name and then you open it, and the person comes out. At least, that’s what the Bookworms do, and I don’t see why you should be different.” What _was_ different, it soon appeared, was the water in the stream in the Cave of Learning, which was quite plainly still water in some other sense than that in which what they were in was water. That is, they could not walk in it; they had to swim. The cave seemed dark, but enough light came from the golden gate to enable them to read the titles of the books when they had pulled away the seaweed which covered many of them. They had to hold on to the rocks—which were books—with one hand, and clear away the seaweed with the other. You can guess the sort of books at which they knocked—Kingsley and Shakespeare and Marryat and Dickens, Miss Alcott and Mrs. Ewing, Hans Andersen and Stevenson, and Mayne Reid—and when they had knocked they called the name of the hero whose help they desired, and “Will you help us,” they asked, “to conquer the horrid Book People, and drive them back to cover?” And not a hero but said, “Yes, indeed we will, with all our hearts.” And they climbed down out of the books, and swam up to the golden gate and waited, talking with courage and dignity among themselves, while the children went on knocking at the backs of books—which are books’ front doors—and calling out more and more heroes to help in the fight. Quentin Durward and Laurie were the first to come out, then Hereward and Amyas and Will Cary, David Copperfield, Rob Roy, Ivanhoe, Caesar and Anthony, Coriolanus and Othello; but you can make the list for yourselves. They came forth, all alive and splendid, with valor and the longing to strike once more a blow for the good cause, as they had been used to do in their old lives. “These are enough,” said Francis, at last. “We ought to leave some, in case we want more help later.”