It has been argued, however, that the Cheshire Cat was an invention of Carroll's...

In Carroll's childhood church (in cheshire) there is a carving on some point of the church-- with a smiling cat-- and as you move (closer? farther away?, to the side?) the cat seems to disappear, but the smile remains..

this was in some annotated volume of Alice in wonderland.. Perhaps someone who has a more information could add to this..

(Not that the whole isis theory isn't interesting, David...)