Turtles all the way down – Wikipedia, the free encyclopedia
A well-known scientist (some say it was Bertrand Russell) once gave a public lecture on astronomy. He described how the Earth orbits around the sun and how the sun, in turn, orbits around the centre of a vast collection of stars called our galaxy.

At the end of the lecture, a little old lady at the back of the room got up and said: ‘What you have told us is rubbish. The world is really a flat plate supported on the back of a giant tortoise.’

The scientist gave a superior smile before replying, ‘What is the tortoise standing on?’

‘You’re very clever, young man, very clever,’ said the old lady. ‘But it’s turtles all the way down.’