Saul Steinberg, “Lowbrow, Middlebrow, Highbrow”; Harper’s Magazine, February 1949.
The original entry at this URL, published 9 February 2014, has been removed. Revised and expanded, it forms a chapter in the book The Rhapsodes: How 1940s Critics Changed American Film Culture, to be published by the University of Chicago Press in spring 2016.
I explain the development of the book in this entry. 
Thank you for your interest!