Once, in Beijing, a young girl in a red gown huddled in a doorway. Like it had been ever since the Chinese industrial 'revolution', it was smoggy and grey. She stared off into the limited distance, trying to peer beyond all the smog.

"Where's mother?" A voice came from behind her.

"Oh, you know the answer to that, Chang'e," she replied. "Go ask dad. I'm sure that he'll say what he's always said."

"What's that?" she asked.

"You're so forgetful..." the girl mumbled.

"But you are too!" said Chang'e. "I bet you don't even remember what father said to you...