I finally got around to reading Steven Madoff's book Art School: (Propositions for the 21st Century), which came out last year. It has some very good essays and interviews - but I loved this Gertrude Stein quote.
The only thing that is different from one time to another is what is seen and what is seen depends upon how everybody is doing everything. This makes the thing we are looking at very different and this makes what those who describe it make of it, it makes a composition, it confuses, it shows, it is, it looks, it likes it as it is, and this makes what is seen as it is seen. Nothing changes from generation to generation except the thing seen and that makes a composition.
- Gertrude Stein, "Composition as Explanation"
You can download a pdf of her essay here.