James Kalm reports on the exhibition of Mark Rothko's Seagram Murals that were on display at the NATIONAL GALLERY as a prelude to the celebrations of the "Washington Color School". As a founder of the Abstract Expressionists Rothko, Still and Newman were designated by Clement Greenberg as "Color Field" painters, an historical segue from the Ab-Exers to Post Painterly abstraction. Rothko is perhaps the quintessential "Color Field" painter.