Full Idea
As philosophers gradually freed themselves from the assumption that all words are names, ..they realised that generalizations really use variables rather than names of abstract entities.
Gist of Idea
We now see that generalizations use variables rather than abstract entities
Source
Roy Sorensen (Vagueness and Contradiction [2001], 8.4)
Book Reference
Sorensen,Roy: 'Vagueness and Contradiction' [OUP 2004], p.132
A Reaction
This looks like a key thought in trying to understand abstraction - though I don't think you can shake it off that easily. (For all x)(x-is-a-bird then x-has-wings) seems to require a generalised concept of a bird to give a value to the variable.