The quality of a smooth, even, broad surface; a surface without curvature; especially a horizontal one. Also, lacking variety in tint or shading; uniform. Not glossy; mat (also spelled matte). And, it may refer to a flat-shaped brush. Although it is an oversimplification of their position, modernist artists and artwriters of the 1960s and early 1970s agreed that the essential characteristic of painting was its flatness, a point of view especially formulated by the critic Clement Greenberg (American, 1909-). This led to post-painterly abstraction on the one hand and to minimalism on the other.An image that takes on flatness in an unusual way:Maurits Cornelis Escher (Dutch, 1898-1972), Balcony, 1945, lithograph, 11 3/4 x 9 1/4 inches (29.7 x 23.4 cm), National Gallery of Art, Washington, DC. In the center of this picture of a hillside town, Escher said he tried to break up the paper's flatness by "pretend[ing] to give it a blow with my fist at the back, but . . . the paper remains flat, and I have only created the illusion of an illusion." See illusion, optical illusion, and perspective.Also see Abstract Expressionism, camera-ready, formalism, French curve, mirror, Op Art, and Pop Art.