 One stark problem for the masses-as-sets view (henceforth we will identify a proponent of this view as a ‘set theorist,’ ignoring its more general meaning), is that it identifies paradigmatically concrete stuffs with what are usually regarded as paradigmatically abstract objects—sets. How could some gold be a set? Suppose we can pick out a definite portion of gold which makes up a ring. If sets are abstract, then the set theorist must say that the gold is abstract. This is pretty hard to swallow. Abstract things are not in time or space, but gold is. Also, sets are not identical to their members. But the gold in the ring does seem identical to the members of the set of gold atoms, not the set itself. (Regarding issues of ‘many-one identity’, see Baxter 1988, Wallace 2011a,b, and see  section 8 of the entry on identity).