I did a graduate degree in creative writing, but my only real writing teachers were the writers I learned from by reading, especially Pinter, Beckett and Gertrude Stein as a young adult. I also learned a lot about writing from the music of Thelonious Monk and Anton Webern and the paintings of Barnett Newman and Mondrian.
I think this piece of mine, from 1980, part of a series, is an illustration of the above.
http://www.loc.gov/poetry/180/113.html
This was the first piece I wrote for a series called Bagatelles, which started as an attempt to come up with a "geometric" literary style inspired by Mondrian, and named after Webern's Six Bagatelles for String Quartet. It was a breakthrough for me as a young writer.