the same thing. (It
might be more proper to say that there are not two (or more) things with the
same extension).

The world then divides neatly into two basic sorts, sets (including
relations) and individuals (or particulars if you prefer) where individuals
are things that have an extension in space time, and sets are things that
have members. 

GH&gt;	Am not sure that this is a precise statement. Do you possibly mean
that sets are really the generic aspects of a group of things, and that that
is what can 