Full Idea
My tentative ontology continues to consist of quarks and their compounds, also classes of such things, classes of such classes, and so on.
Gist of Idea
My ontology is quarks etc., classes of such things, classes of such classes etc.
Source
Willard Quine (Structure and Nature [1992], p.9), quoted by Stewart Shapiro - Philosophy of Mathematics 4.9
Book Reference
Shapiro,Stewart: 'Philosophy of Mathematics:structure and ontology' [OUP 1997], p.142
A Reaction
I would call this the Hierarchy of Abstraction (just coined it - what do you think?). Unlike Quine, I don't see why its ontology should include things called 'sets' in addition to the things that make them up.