Eivind (like the Terrible) quoted Pyramids by Terry Pratchett (Discworld, #7)
Young Prince Teppic is sent far away from his desert homeland to the city of …
“Fastest animal on the face of the Disc, your common tortoise,” said Xeno, but he had the grace to look shifty. “Logically, that is,” he added.
— Pyramids by Terry Pratchett, Alfred Enoch (Narrator) (Discworld, #7)