Turtles All the Way Down

"The world is but a flat disc* resting on the backs of four elephants, one each supporting its north, south, east and west edges."

"But what supports the elephants?"

"The elephants stand firm on the back of a giant tortoise."

"But what supports the giant tortoise then?"

"The tortoise rests on the back of a larger tortoise."

"Then what supports the second tortoise?"

"Simple one, how daft you are. It's turtles all the way down!"