"...there are some people who have a legend that the whole universe is carried in a leather bag by an old man.
They're right, too.
Other people say: hold on, if he's carrying the entire universe in a sack, right, that means he's carrying himself and the sack inside the sack, because the universe contains everything. Including him. And the sack, of course. Which contains him and the sack already. As it were.
To which the reply is: well?"
- Sir Terry Pratchett, The Last Continent