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.”
Polly looked puzzled.
“Don’t you see？” said Digory. “No， do listen. Think of our tunnel under the slates at home. It isn‘t a room in any of the houses. In a way， it isn’t really part of any of the houses. But once you‘re in the tunnel you can go along it and come into any of the houses in the row. Mightn’t this wood be the same？.a place that isn‘t in any of the worlds， but once you’ve found that place you can get into them all.”
“Well， even if you can.” began Polly， but Digory went on as if he hadn‘t heard her.
“And of course that explains everything，” he said. “That’s why it is so quiet and sleepy here. Nothing ever happens here. Like at home. It‘s in the houses that people talk， and do things， and have meals. Nothing goes on in the in.between places， behind the walls and above the ceilings and under the floor， or in our own tunnel. But when you come out of our tunnel you may find yourself in any house. I think we can get out of this place into jolly well anywhere！ We don’t need to jump back into the same pool we came up by. Or not just yet.”
“The Wood between the Worlds，” said Polly dreamily. “It sounds rather nice.”
“Come on，” said Digory. “Which pool shall we try？”
“Look here，” said Polly， “I‘m not going to try any new pool till we’ve made sure that we can get back by the old one. We‘re not even sure if it’ll work yet.”
“Yes，” said Digory. “And get caught by Uncle Andrew and have our rings taken away before we‘ve had any fun. No thanks.”
“Couldn’t we just go part of the way down into our own pool？” said Polly. “Just to see if it works. Then if it does， we‘ll change rings and come up again before we’re really back in Mr Ketterley‘s study.”
“Can we go part of the way down？”
“Well， it took time coming up. I suppose it’ll take a little time going back.”
Digory made rather a fuss about agreeing to this， but he had to in the end because Polly absolutely refused to do any exploring in new worlds until she had made sure about getting back to the old one. She was quite as brave as he about some dangers （wasps， for instance） but she was not so interested in finding out things nobody had ever heard of before； for Digory was the sort of person who wants to know everything， and when he grew up he became the famous Professor Kirke who comes into other books.
After a good deal of arguing they agreed to put on their green rings （“Green for safety，” said Digory， “so you can‘t help remembering which is which” ） and hold hands and jump. But as soon as they seemed to be getting back to Uncle Andrew’s study， or even to their own world， Polly was to shout， “Change”， and they would slip off their greens and put on their yellows. Digory wanted to be the one who shouted， “Change”， but Polly wouldn‘t agree.
They put on the green rings， took hands， and once more shouted “One.Two.Three.Go” . This time it worked. It is very hard to tell you what it felt like， for everything happened so quickly. At first there were bright lights moving about in a black sky； Digory always thinks these were stars and even swears that he saw Jupiter quite close.close enough to see its moon. But almost at once there were rows and rows of roofs and chimney pots about them， and they could see St Paul’s and knew they were looking at London. But you could see through the walls of all the houses. Then they could see Uncle Andrew， very vague and shadowy， but getting clearer and more solid.looking all the time， just as if he were coming into focus. But before he became quite real Polly shouted “Change” ， and they did change， and our world faded away like a dream， and the green light above grew stronger and stronger， till their heads came out of the pool and they scrambled ashore. And there was the wood all about them， as green and bright and still as ever. The whole thing had taken less than a minute.
“There！” said Digory. “That‘s all right. Now for the adventure. Any pool will do. Come on. Let’s try that one.”
“Stop！” said Polly. “Aren‘t we going to mark this pool？”
They stared at each other and turned quite white as they realized the dreadful thing that Digory had just been going to do. For there were any number of pools in the wood， and the pools were all alike and the trees were all alike， so that if they had once left behind the pool that led to our own world without making some sort of landmark， the chances would have been a hundred to one against their ever finding it again.
Digory’s hand was shaking as he opened his penknife and cut out a long strip of turf on the bank of the pool. The soil （which smelled nice） was of a rich reddish brown and showed up well against the green. “It‘s a good thing one of us has some sense，” said Polly.
“Well， don’t keep on gassing about it，” said Digory. “Come along， I want to see what‘s in one of the other pools.” And Polly gave him a pretty sharp answer and he said something even nastier in reply. The quarrel lasted for several minutes but it would be dull to write it all down. Let us skip on to the moment at which they stood with beating hearts and rather scared faces on the edge of the unknown pool with their yellow rings on and held hands and once more said “One.Two.Three.Go！”
Splash！ Once again it hadn’t worked. This pool， too， appeared to be only a puddle. Instead of reaching a new world they only got their feet wet and splashed their legs for the second time that morning （if it was a morning： it seems to be always the same time in the Wood between the Worlds）.
“Blast and botheration！” exclaimed Digory. “What‘s gone wrong now？ We’ve put our yellow rings on all right. He said yellow for the outward journey.”