ssion is different from set membership.

JA: Something about this sort of statement really sounds wrong to me.
    I have wrestled with it for a couple of days now, and here is the
    best that I can work out for the time being.
 
JA: 1.  Sets are mathematical objects.
 
JA: 2.  Elements of sets are mathematical objects.
 
JA: If you cannot imagine what in the world such statements might mean,
    please feel free to interpret them as idiomatic figures of speech,
    affording the paraphrase that sets and 