“Silence， sir！” said Uncle Andrew， bringing his hand down on the table. “I will not be talked to like that by a little， dirty， schoolboy. You don‘t understand. I am the great scholar， the magician， the adept， who is doing the experiment. Of course I need subjects to do it on. Bless my soul， you’ll be telling me next that I ought to have asked the guinea.pigs‘ permission before I used them！ No great wisdom can be reached without sacrifice. But the idea of my going myself is ridiculous. It’s like asking a general to fight as a common soldier. Supposing I got killed， what would become of my life‘s work？”
“Oh， do stop jawing，” said Digory. “Are you going to bring Polly back？”
“I was going to tell you， when you so rudely interrupted me，” said Uncle Andrew， “that I did at last find out a way of doing the return journey. The green rings draw you back.”
“But Polly hasn’t got a green ring.”
“No，” said Uncle Andrew with a cruel smile.
“Then she can‘t get back，” shouted Digory. “And it’s exactly the same as if you‘d murdered her.
“She can get back，” said Uncle Andrew， “if someone else will go after her， wearing a yellow ring himself and taking two green rings， one to bring himself back and one to bring her back.”