What reason do you have to believe the earth is flat?
It is a magical world in the shape of a disc which - as in certain well-known ancient cosmologies - is mounted on top of four giant elephants which are standing on a giant turtle. The turtle's name is A'Tuin, more often known as the Great A'Tuin. I believe Rincewind nearly fell off the edge once, being a rather inept wizard and all.
