"Oh, papa, weren't Knowall and his followers in Greenland awfully sad the way things had turned out?"
"For a while. Then Knowall came up with the final pay-off."
"Is that slang, papa? Pay-off?"
"Yes. The coup-de-grace. The ace in the hole that he'd saved, if all else failed."
"I understand, papa. The idea that would out-trump anything the other side had to offer. What was it, father? What did they have?"
"Knowall imbued the An-vils with nostalgia."
"What is nostalgia?"
"Home sickness."
"Oh, papa, wasn't Knowall smart? That meant, the An-vils were all filled with the desire to fly back to the star from where they had started."
"Exactly. So, one day, all the An-vils, an immense army, flapping their great green wings, assembled in the Black Hills of North America, and, at a given signal, they all rose up from Earth and all the humans chanted, 'Glory, glory, the day of our deliverance!'"