Full Idea
The problem of abstraction is exactly the same as that of general ideas. We call what characterises general ideas abstract.
Gist of Idea
Abstraction is just the character of generalisation
Source
Simone Weil (Lect 1: Materialist Viewpoint [1933], p.59)
A Reaction
Note that is not general ideas which are abstract, but what 'characterises' them. Is resemblance an intermediate step between generalisation and abstraction? The concepts seem to develop in stages.
Book Reference
Weil,Simone: 'Lectures on Philosophy' [CUP 1978], p.59