In the hallway of university Wittgenstein asked a collegue "I've always wondered why for so long people thought that the sun revolved around the earth." "Why?" said his surprised interlocutor, "well, I suppose it just looks that way". "Hmm", retorted Wittgenstein "and what would it look like if the Earth revolved around the Sun?". This puzzled the interlocutor.

Sorry, this is not the official starting point. Just ask me for proper links :o)