"Consider, for another example, the men who called Copernicus mad because he 
proclaimed that the earth moved.  They were not either just wrong or quite 
wrong.  Part of what they meant by 'earth' was fixed position.  Their earth, 
at least, could not be moved.  Correspondingly, Copernicus' innovation was not 
simply to move the earth.  Rather, it was a whole new way of regarding the 
problems of physics and astronomy, one that necessarily changed the meaning of 
both 'earth' and 'motion.'  Without those changes the concept of a moving 
earth was mad."
(Thomas S. Kuhn, _The Structure of Scientific Revolutions_, pp. 149-150.)
Andrew Kliman