CADET CHALLENGE # 6

Here's an easy challenge (SUPPO is feeling too challenged and wants something easy):

How many wheels does a bicycle have if you call the seat a wheel?  'Splain.  ...never mind.  She got it right.  (The answer:  Two.  Calling the seat a wheel doesn't make it so.  Next question:  I changed the form of the riddle so it couldn't be Googled.  What was the original, and who is famous for it?)