http:// wordsmith.org/board/showflat.pl?Cat=&Board=words&Number=6120)

Isn't this another incarnation ofwhat is officially called Russell's Paradox? There are classes which include themselves, and classes which don't include themselves - to which one does the class-of-things-that-do-not-include-themselves belong? (Substitute "catalog" for "class" if it makes it more concrete.)