This early painting by Piet Mondrian is a wonderful precursor to abstraction. It's also a strong example of what Greenberg considers the avant-garde, or the opposite of kitsch. Here, Mondrian is playing with space, color and shapes in a new way, and therefore avoids painting something that is predictable. According to Greenberg, something like Composition in Brown and Gray is daring and esoteric (avant-garde), not mechanical or formulaic (kitsch).
Norman Rockwell's work is best known for his many cover illustrations - all depicting snippets of American life - on the covers of The Saturday Evening Post. It best represents the kind of art that Greenberg identifies as kitsch or ersatz culture; a piece of popular, commercial art, or better yet, a product of the industrial revolution, devised to sell something. According to Greenberg, art of this type doesn't even want the viewer's time, just money. But Greenberg doesn't believe that kitsch is necessarily bad; at least, he claims, kitsch is honest.
In his essay "Collage," Greenberg considers the issue of flatness, or rather, of how Picasso and Braque obsessed over space and dimension in their Cubist collage works. In Georges Braque's Man with a Guitar, Greenberg points out that the canvas' flatness isn't something Braque tries to hide; instead, he uses various shapes and trompe-l'oeil (an optical illusion of three dimensionality, in this case the tassel-and-stud in the upper-left-hand margin), in order to emphasize the surface flatness. According to Greenberg, Braque is using collage to expose the illusion of depth and to ultimately depict the absolute flatness of the picture surface. This directness in foregrounding the constraints of the picture plane is a signature element of both abstract and representational art.