“Oh！ I know，” said Digory. “Of course it won’t work. We‘re still wearing our yellow rings. They’re for the outward journey， you know. The green ones take you home. We must change rings. Have you got pockets？ Good. Put your yellow ring in your left. I‘ve got two greens. Here’s one for you.”
They put on their green rings and came back to the pool. But before they tried another jump Digory gave a long “O.o.oh！”
“What‘s the matter？” said Polly.
“I’ve just had a really wonderful idea，” said Digory. “What are all the other pools？”
“How do you mean？”
“Why， if we can get back to our own world by jumping into this pool， mightn‘t we get somewhere else by jumping into one of the others？ Supposing there was a world at the bottom of every pool.”
“But I thought we were already in your Uncle Andrew’s Other World or Other Place or whatever he called it. Didn‘t you say.”
“Oh， bother Uncle Andrew，” interrupted Digory. “I don’t believe he knows anything about it. He never had the pluck to come here himself. He only talked of one Other World. But suppose there were dozens？”
“You mean， this wood might be only one of them？”
“No， I don‘t believe this wood is a world at all. I think it’s just a sort of in.between place.”