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.
