Full Idea
The subject-matter of (pure) mathematics is abstract structure per se.
Gist of Idea
The subject-matter of (pure) mathematics is abstract structure
Source
Michael Jubien (Ontology and Mathematical Truth [1977], p.115)
Book Reference
'Philosophy of Mathematics: anthology', ed/tr. Jacquette,Dale [Blackwell 2002], p.115
A Reaction
This is the Structuralist idea beginning to take shape after Benacerraf's launching of it. Note that Jubien gets there by his rejection of platonism, whereas some structuralist have given a platonist interpretation of structure.