Bertrand Russell was once talking about the Earth turning around the sun.
In the middle of the speech, an old man stood up and protested against Russel's words, "Oh young, you are very intelligent. There is no doubt in this. But we do not know that the world is flattening and it is carrying on the back of the tortoise.
Russell was surprised to hear about the old man. The question is OK. So you said now, what is the tortoise stand on?
The old man said a little worried and said, 'I tell you, and you learn it!'
