Full Idea
The wood is, as it were, a relatively unstructured version of the tree, just as the set {a,b,c,d} is an unstructured counterpart of the set {{a,b},{c,d}}.
Gist of Idea
The matter is a relatively unstructured version of the object, like a set without membership structure
Source
Kit Fine (Things and Their Parts [1999], §5)
Book Reference
-: 'Midwest Studs in Philosophy' [-], p.73
A Reaction
He is trying to give a modern logicians' account of the Aristotelian concept of 'form' (as applied to matter). It is part of the modern project that objects must be connected to the formalism of mereology or set theory. If it works, are we thereby wiser?