Full Idea
Cantor gives informal versions of the axioms of ZF as ways of getting from one set to another.
Gist of Idea
Cantor gives informal versions of ZF axioms as ways of getting from one set to another
Source
report of George Cantor (Later Letters to Dedekind [1899]) by John Lake - Approaches to Set Theory 1.6
Book Reference
'Philosophy of Mathematics: anthology', ed/tr. Jacquette,Dale [Blackwell 2002], p.366
A Reaction
Lake suggests that it should therefore be called CZF.