Full Idea
Not how an expression can be etymologically derived and determined analytically, but how it is used is the question. Origin and use are often very different.
Gist of Idea
Study the use of words, not their origins
Source
Johann Gottfried Herder (works [1784], p.153), quoted by Andrew Bowie - Introduction to German Philosophy 2 'Herder'
Book Reference
Bowie,Andrew: 'Introduction to German Philosophy' [Polity 2003], p.53
A Reaction
This doesn't quite say that meaning is use, and is basically an attack on the Etymological Fallacy (that origin gives meaning), but it is a strikingly modern view of language.