e:
&gt; Notice it only arises for entities that are located in space
&gt; and time: abstract things like sets and numbers are not classified in
&gt; either of these ways. (Note in particular that a set of physical
&gt; things is not itself physical.)
&gt; 
&gt; Are you taking physical and abstract as two sides of the same 
&gt; distinction
&gt; here - or are there more types. It also seems to me that the complete
&gt; banning of spatio-temporal location for sets can be 
&gt; problematic if you want
&gt; to 