A wolf and a lamb both came to the same stream to drink; the wolf upstream, the lamb downstream.
The wolf eyed the lamb hungrily, thinking of some excuse to kill and eat him. "Stop muddying my water!" he howled.
"I don't understand," bleated the lamb. "The water flows down from you to me, not up."
The wolf invented another excuse. "I remember you insulted me six months ago!"
"I wasn't even born then," said the lamb. "I'm only three months old."
"Well, that must have been your father!" snarled the wolf, who then attacked the lamb and devoured him.
Inspired by: Mille Fabulae et Una, a collection of Latin fables that I've edited, free to read online. I am not translating the Latin here; instead, I am just telling a 100-word version of the fable.
Notes: This is fable 311 in the book, which is Perry 155.