Cartesian Diver

Did you know that Rene Descartes met the Hunchback of Notre Dame? They were both visiting Paris, and met on a ferry crossing the famous river. Somehow Quasimodo fell overboard. He disappeared under the water because of the weight of handbells he was carrying on his belt. As Descartes began a rescue, he shouted, "Quasimodo, I see where you are," and plopped on his coordinates. He found Quasimodo was already headed toward shore. He seemed to be running across the bottom, but then Descartes saw he was dancing! Descartes signed to him: "What are you doing that for?"

Quasimodo signed back, "Save yourself! I'm happy. I'm just Ringing In The Seine!!" So Rene reached the shore by bobbing up and down.

An onlooker asked, "How did you do that?"

"I'm a Cartesian diver," replied Descartes.

"I realize, 'I sink.' Therefore I swam."